David, you’re not old, you are a Classic. Your tips and engineering expertise are phenomenal. I find your information extremely useful for my small 4 cylinder race engine builds. Thank you Professor David.
Good tips david. I'm 73 years old.... still driving my 64 mini cooper s... thanks to your 'tips' on those ! Anyway... Did lots of drag racing in the past. All 354 and 392 chrysler supercharged stuff. Even tho we used only gears for timing we still spent hours getting the 'slack' just right. To tight , even on gears , cost hp. To loose and it was even worse ...causing 'spark scatter' and costing hp and possibly blower explosion !
Hi, I figured out / learned the lesson when I was 10 years old in the early 1960's. I really tightened the chain up tight on my bike and found I could hardly peddle it, then playing around after a while the chain broke. When I started building engines and racing I made sure the timing chain was a little loose. I believe today you can get under size sprockets for non nylon type sprockets. By the way the Chevy nylon sprocket is 1/2 inch wide the 1958 Corvette was 5/8 wide. Don
Here's an interesting anecdote for you all, based on my build and repair experience of Caterpillar C15's... The specificaton for harmonic damper/balancer replacement is 500,000 to 600,000 miles, depending on the application, and also specified by CAT to be done at leaking front seal replacement. If not changed out at seal replacement, the seal will begin to leak again within a very short time, and it has nothing to do with the condition of the running surface of the damper where it contacts the seal as it's a two piece seal, where the inner part of the seal is a sleeve that rotates with balancer. Furthermore, when the damper is changed, it improves the fuel consumption by approximately 8 to 10%, which is noticeable immediately after seal and balancer changeout, even when no other repairs to the engine are being performed. The conclusion drawn to by myself and peer colleagues is, the damper is an accumulator of energy at the firing of each cylinder, and that, the elasticity performance of the rubber between the two damper parts deteriorates, and although it may not appear to be damaged or broken, on a micro level the bonding of rubber particle does become compromised.
I don't remember just how many hours John Deere also recommended changing the front pulley assembly also, It my have been only on certain models and applications.
Also, if the damper rubber gets too weak, the damper can lay over to one side, creating a negative inertial torque moment which can not only rob power, but cause main journal failure and crank shaft cracking.
I was wondering the same, I think they have their limit within rpm, but I don't know. Only what I've seen on a chart , BUT those charts may be from a competitor brand and not quite truthful !
Way off the subject here but kinda interesting.... had a 327 chev that was pro built... always had very , very , slight harmonic vibration at different rpm's. That was with the high performance big 8" corvette balancer. Switched to the FluidDamper and eliminated all harmonic vibrations ! Sorry.. way off the main subject here but just thought I'd throw that out...
My experience from running too tight of a timing chain is that the front cam bearing wears in (i.e. excessive wear) before the chain and gears break-in. This makes sense since the cam bearing is much softer than the steel chain and gears.
As well as crank bearings, most already have a belt pulling on them, old Buicks need a very tight power steering belt heard many front main bearings slap before oil pressure, and they have weak pumps.
I experienced the same thing with a 2.2/2.5L mopar 4 popper. It didn't have a automatic belt tensioner and everytime I set the tensioner too tight, it would break the cam after about 500 miles no sweat. Went thru 3 cams before I referenced the OEM service manuals and saw that I was goin too tight. Set it to OEM spec and had no issues with the cam for the years after I had the car.
Interesting .. I would have never thought the power loss would be 11hp and the fact that the gear would be worn, that interesting as well. A loose timing chain was said to be caused by stretch and a worn gear contributed to the loose chain was never considered in my experience. I can't wait to see what other knowledge nuggets you have to share in the future.
As always David thank you so much for sharing your vast knowledge!! Wish I’d known you when I was a young man. I absorb this like a sponge. My mind spins constantly pondering how to make things better!! Faster stronger!!
A frequently overlooked factor I’ve seen, is distributor gear backlash and the resulting chatter not only resulting in ignition scatter, but, crazy vibes being fed back into the camshaft. I’ve also wondered if it may have contributed to oil pump issues.
They always put the oil pump on the end of the distributor shaft for the purpose of keeping the slop in the skew gears in check = of no effect. Also pretty sure the forces the camshaft deals with are about an order of magnitude larger than the oil pump+distributor forces so they can be neglected. However when you go changing the valvetrain from stock and standard stuff then you really should figure out some sort of crank trigger system. The high voltage spark distribution function will tolerate a fair amount rotor-cap phasing error (as witnessed by every stock vacuum advance system introducing rotor-cap phasing error)(well - except for some old engines that turned the entire distributor = four main bearing Chevy Sixes) But the problem with crank triggered stuff is how to come up with centrifugal advance = and even worse you need to keep a stock type centrifugal advance in the distributor = and they need to match to keep rotor-cap in synch ! Good luck - I never did figure out a good Old School Way to keep all the cam wind-up and wind-down from affecting ignition timing, I run a Pontiac and the stock water pump may have to go so I can cobble together some kind of ultra-short distributor run off the front end of the cam. It's a headscratcher.
@@stujones3566 Once I saw a magazine article where a guy took a V8 distributor and machined it to have little sealed ball bearings in it instead of engine-oil bushings. He laid it down and faced it back along the block and made brackets to hold it and allow for timing adjustments. Finally he machined a little cog-belt pulley and got it on the crank snout behind the harmonic balancer. Finally he put a twice-as-big cog pulley on the drive end of the distributor (to get the 2-1 geardown). It worked great on a dragster but real car engines have a crossmember and engine mounts down there on both sides. Sure would be fun getting under it to change points, have oil dripping on your ignition, and making a cover to keep sticks and stones out of your belt drive ! So the search goes on . . . I am really starting to envy guys whose engines drive the distributor off the FRONT of the camshaft (but hey their oil pump has to suck oil from the where it's all glued to the back of the block by acceleration - up to their front mounted oil pump.)(gah - seems like there's no easy solution!)
Thank you for this knowledge sharing, I would not have thought of this remarkable loss. If timing gears are used instead, have you Dyno tested timing chain vs a timing gear setup? Again, I really appreciate how you use your time to share your extensive experience with us.
It’s not just friction with an initially tight timing chain. As the chain spins faster it flings out from the cogs a little bit and gets even tighter. Thanks brother!
WHAT i've found is that tight timing chains will rub the bottoms of the cam bearings and reduce the effectiveness of the hydrodynamic lubricating wedge and literally eat the bearings causing a lot of unnecessary bearing scrub,timing chain components have to be matched to the load put up on the vehicle ,in racing,constantly changed,everyday driving,every 85 to 125k or the retarded timing with eat the exhaust valves and seats right out of the head,DAVID IS THE ONLY ONE WHO HAS EXPLAINED THIS PROBLEM perfectly,this is the man who has been there,learning BY DOING,thanks DAVE
I’m building my first small block Chevy in 37 years right now working with a very reputable machine shop owner. Excited to see how it goes. Thank you David
My 5.7 LT1 has over 170k miles so I'm gonna try to do a mild rebuild/refresh. A timing set is on my list. I will definitely remember this information. And Cloyes is definitely the brand I'm buying
Wise words excellent channel and thank you, words of experience and I never looked at it like that, and your right the gear teeth wear as well, I checked with a new chain it was loose as the old chain same original block not line bored so now am going to buy a set with new gears and use my old chain and see thank you I subscribed cheers from 🇦🇺
The linkbelt timing chains wore like the devil. A guy I worked with used to say when doing a tuneup, if the timing chain had any more than 30k miles you needed to replace it. Without doing so he said, you could never get the engine to run 100%. To a point he was correct but a little anal about it. My experience was 50k to 60k was kind of the wear limit. Now we need to realise oils and metalurgy were not what we have today. For long life a truroller timing set is the answer as they will generally go 100k miles or more. You can rotate the crankshaft forward and backward to just take up the timing chain slack to get an idea of the state of wear without removal of the timing cover.
Oops! That was a shorty. Well done. Thank you. Looking forward to the next episode. ps: hopefully you read my comments. May be you can answer some of them in a new episode (?). Thank you.
I definitely see where the pressure against the bearings and resonant crank harmonics can both cause massive power loss. Another thing besides simple friction, there is also dimensional harmonic throw, and resultant lifter knocking and lifter drop. In other words, 1: the vibrations from the crank CAN cause the cam to flex [imperceptibly to the naked eye, but with a really close up high speed camera you could see it] and this can both cause the rotating mass of the cam shaft experience centripetal rotational resistance because of the laws of conservation of momentum, which, by its nature, creates moments of negative torque, which travels back to the crankshaft, and stealing that torque from the entire system. 2: this flexation will cause the cam journals to impinge upon the cam bearings more, pushing through the layer of oil, causing them to potentially collide with the bearings, not only adding friction, but causing wear. 3: the same flexation will change the 'effective' cam-to-lifter contact, meaning that at unreliable, and irregular intervals, the lobes will be either further out [causing increased lift] or further in [causing decreasing lift]. While this may not seem very important 'as long as it all averages out in the end', it in fact is VERY important, as it leads to INCREASED harmonic IMBALANCE in the crank shaft, potentially leading to an infinite feedback loop and the destruction of the engine at an accelerated rate, and robs all engines of total horsepower when they are fed an imbalanced volume of air and fuel mixture. To clarify point 3-B, when cylinders deviate from a uniform output level, this not only increases vibrations, and crank shaft stress, it also brings the average BELOW even the lowest cylinder value, therefore bringing the total net collective value down. This is something that was proven back as early as the 1930's when early race cars were being experimented on and they were being built with substandard parts, but was soon forgotten because racing engines were eventually going from hand built individual creations to products of a uniform engine manufacturing system which reduced these irregularities a lot, AND where both total horsepower and engine speeds were quite low, as compared with today's modern engines. The facts were always there, but they were forgotten because of the development curves in the industry, where high engine speeds and lower displacement engines where the effects are more pronounced had not really come into existence yet. As one perfects an engine, they can expect to run into new, or, more correctly, little known issues which few people ever wrote about very much. For instance: one of the best possible ways to prevent this kind of whipping of a camshaft, just like with crank throws on a high performance engine, is to increase the barrel thickness of the cam while boring it out hollow. As a 'drilled' or 'bored' cam, you can maintain the same total mass, and same total volume of metal, but with a stronger, more rigid form, so that it will be much less prone to whipping. That does not remove the need for proper cam chain tension, but it will greatly improve it. Also, hollow-grinding all of the cam lobes would help a lot as well, but that is some really high end machining! All of this is making me think perhaps I need to be building a new kind of cam shaft.
Smokey Yunick had cams ground backwards so he could run a single gear timing gear drive like a 300 Ford 6. He recommended a 4-7 swap reverse rotation cam with a single gear to gear set chainless, like a Ford 240-300 6.
They've got their place, I've got a newfound respect for belts. About a month ago, I replaced a broken belt on a 2.3 ford that powered a generator. It was an early 80s model ,with 1700hrs on it and was the original belt. Gotta love non-interference engines, and I wonder if the new belt will last another 40yrs.
@@MrTheHillfolk what sparked my curiosity was David mention a loose chain, dampen more vibrations to the crankshaft and camshaft, and I believe a belt being rubber with dampen it even more, and I’ve noticed Steve Morris engines, uses belts and not chains on his motors, but I’d love to hear David’s perspective
David: I’m a regular for info on the Uncle Tony 318 build info, we out here are blessed to be able to tap into what you have learned over the span of years that you have been doing this! I have always wondered about “ gear cam drives” the timing chain tension is interesting! Especially at my age of 75 having dealt with this problem with the many engines that I have built! Seems to me the more slop there is in the chain it would change your cam timing logically thinking, which is why we have an adjustable distributor whereas you can check the timing at the crank pulley! The tighter the timing chain the closer the relationship of everything to the designed running timing specification of the particular engine! Is my thinking correct!? So what about if it is set up with a gear cam crank set up? And what do you think of gear drives? I don’t think gear drives are available for Mopars regardless of that I’d like to know what you think about gear drives? Regards Mad Mike S. …….
LOL sounds like something smokey would say but I think it's a better system than a timing belt or an aftermarket retrofitted gear drive but oem gear to gear systems are usually pretty damn reliable and you can rev them to the moon as long as the valve springs can keep up.
@@rustybritches6747 the problem with gears is they cost more power than a proper sized chain. A belt ultimately costs the least amount of power. Friction is the loss. Gear drives by nature have more surface area in constant contact therefore loose the most amount of power. A gear drive keeps timing as consistent as can be though
I've also never liked the look of the chains with no tensioner or anything, always seemed like a halfassed solution that I'm surprised works as well as it does. I guess it may have made more sense when rings were soft iron and the engine overhaul interval of a typical passenger car was like 50k miles, you wouldn't be going in often just to change a sloppy chain in that world.
Back in 1972 one of my first builds was a 283 chevy with a Cloyes three position crank sprocket it took several tries to get the chain and sprockets assembled. Remember that well. It might be with a line hone on the main bearing bores the chain would loosen up a bit.
Have you ever checked your cam timing from both banks? I was checking my cam timing on a hot rebuilt 1967 Buick 430. I adjusted the timing on the #1 cylinder as usual. I decided to verify the timing on cylinder #2, and it was 4 degrees off! It was 4 degrees late. I then proceeded to check all cylinders, and sure enough, cylinders 1, 3, 5 and 7 were the same, while 2, 4, 6 and 8 were 4 degrees late! I consulted TA-Performance who supplied the cam, heads and everything, and they suggested to split the difference between banks. I think this is due to sloppy machining of the lifter bores in the block at the factory.
I would suspect that timing set was mis packaged, probably intended for a block that was line bored excessively so the crank to cam spacing would be reduced leaving proper slack in the chain.
That being said, EXCELLENT information on all of your videos. Thank you for all that you share with us viewers! I'll be using a great deal of this info on my next sbc build!
I can't say this is any proper test,but i ran a pete jackson gear drive in my 482 big block chevy from 1988 to 1998 and it was my daily driver in a 70 chevelle. using a .670 .690 lift roller with 312-322 advertised duration,13:1 compression,3.73 rear end gear. The car ran 10.60's at the track on weekends and was street raced excessively. In those 10 years the timing was dead rock steady and i never experienced issues from harmonics hurting spring pressures as some claim. that being said its critical to set the gears up correct for clearances. One persons account does not make a study,but i run gear drives in everything i have including a high 9 second tubbed 88 S-10 truck.
i'm wondering if an align hone of the bearing saddles on another block would help that tight timing chain get some slack if transfered over, due to the crank moving up towards the cam bearings in the second block
The weak link I see on V-8 engines are chain drives. After 150.000 miles, most chains are shot. Most new engines are running tensioners. How do we feel about chain tensioners. AND Smokey Yunick was a big fan of gear drives
I was gonna replace the timing chain tensioner when I rebuilt my 4.2 Ford v6 then I took it completely off and saw there was no way it could possibly skip a whole tooth and put the old one back in it.been like that for two years now.
I notice.that too tight anything saps power, you may be miles before everthing in that block is friendly. Pop on new heads, +10-20 hp. Index your plugs, also my timing is always 1 tooth plus on the crank to take the mechanical advantage of the piston going down and not getting resistance from TDC to crank relation.
Thanks for another great video jam packed for of knowledge and experience. @DavidVizard in your porting series do you plan on porting any 4 valve heads? I need all the help I can get. Thank you
I wonder if an advanced oil formulation of MoDTC with a synergistic addition of ZDDP or MOLYVAN-855 in the oil which are advanced anti-friction components that work thru a plating-effect & if they could also dampen crank harmonics...
Thank you for sharing your knowledge with us , I’ve always wondered if gear drives are worth the supposed extra harmonics vs accuracy? That said I’ve a Jackson .005 allign honed set on a n/a 355 with 5 seasons of open wheel usage & now in a 2450 lb super gas car as a starter engine for kiddo & it ran 10.80 @122 w a set 461 heads i home ported & a flat tappet solid cam. I wonder if I should have used a chain , but it’s a reliable little mill , thoughts welcome 🙏
My thoughts are you should have gone with a Mopar, BUT that's my thoughts on everything. (AND NOT A THIRD GEN HEMI) Sounds like a lucky kid to get to start out with a rig like that. 👍 It's been my own experience that DV has it right, belt drive is the pinnacle but I've used gears and never had a problem, though it was not a race engine, overkill just to talk about with my friends
Pulled down this rebuilt engine that I got in a car for some upgrades and found that the timing chain was so tight, the front cam bearings had worn into the copper. Prob used the wrong set or it was packaged wrong But supposedly it didn't have a lot of miles on it and I believe that because it was a efi car that wasn't set up right at all. Not one sensor hooked up!
This makes me wonder if I should delete the timing chain tensioner on my 5.2 magnum 390 stroker motor. These engines have a longer timing chain than a small block Chevy because the camshaft set's higher up in the block. Those tensioners make the timing chain super tight.
Can you buy timing chains with different lengths? I ask because sometimes, if the block is alignbored too much, you might have the other side of the problem. I know one machine shop that created a dampener/tension device on an old Pontiac block to take up the slack. Sounds like they could have save a lot of time/effort with a proper length chain. I also seem to recall a lot of discussion about true roller, vs. gear drive, vs. belt drive - where belt drive was the best on horsepower. Is that still the case?
Have a big block chevy race motor. It has been line honed maybe 3 times. Put it back together noticed a very slack timing chain. Ordered up cloyes new timing set up -.02 much better. Snug maybe 1/16-1/8 ? Roller cam . Now I'm concerned.
I’d like to ask the hp cost of a double row timing chain, and at what point do you have to use them, an ls runs a single, when would you have to double up.
This is another reason that the manufacturers went to timing belts. The belt actually dampens the harmonics in the engine! The other one of course and belt material improved is cost and profit from maintenance!
As a young boy in the early 80s every old motor I swapped a cam into had a pan full of nylon teeth off the timing gears. Those motors must have been making an extra 30 HP. lol
You talked previously about a belt system being the best choice. Are belt systems readily available for most motors? Thanks for another great video David
David Vizard, a question....Would cam bearings that are tight enough that the camshaft (by itself) can only be turned with a wrench on the cam bolt, would that cause similar power loss numbers as too tight of a chain (less,more) ?
You mentioned vibration dampers (notice I didn't say "harmonic balancers"!). What STYLE and brand do you use? Surely there's power to be gained or lost there as well.
Makes me wonder what the cam timing is doing on my coyote, even though the vvt is deleted still alot of chains. Cam timing might be more of suggestion for my motor.
Big Chief runs a European timing chain. I can't remember the name. It moves more freely than your most popular chains. He it running a Small block with Pontiac Nascar type heads alot of RPM and turbos.
Too tight of cam chain will eat the cam bearing as well. I have seen it with my own eyes. 20,000 mile engine that looked great except for the front cam bearing. Only noticed it because my friend was doing a cam change.
Typically 'timing chain/gear' power losses are not from the chain/gear drive dragging and causing friction. It's from incorrect crank to camshaft phasing-related issues. In any engine, a few degrees of cam phasing in the wrong direction can easily knock fuel efficiency down by several percent or more in its primary operational RPM band.
So, besides parasitic loss from the crank (2-3 HP) with a relatively tight timing chain, I missed what other drivers were a possible factor aside from "the Dyno told me so"?
AFAIK there is really only one decent brand of timing chain. JWIS from Germany. And even they do not last very long before going slack moving cam timing. There is tight and excesivly tight though and that usually comes back to the gears being a touch too large,, or small. I have had one of those chains break as well, was not peined properly and it disconnected itself. Under 5000 miles in a very mild 400 Ford.
David, you’re not old, you are a Classic. Your tips and engineering expertise are phenomenal. I find your information extremely useful for my small 4 cylinder race engine builds. Thank you Professor David.
Good tips david. I'm 73 years old.... still driving my 64 mini cooper s... thanks to your 'tips' on those ! Anyway... Did lots of drag racing in the past. All 354 and 392 chrysler supercharged stuff. Even tho we used only gears for timing we still spent hours getting the 'slack' just right. To tight , even on gears , cost hp. To loose and it was even worse ...causing 'spark scatter' and costing hp and possibly blower explosion !
Thank you David! Your wealth of knowledge that you freely share is priceless!
Hi,
I figured out / learned the lesson when I was 10 years old in the early 1960's. I really tightened the chain up tight on my bike and found I could hardly peddle it, then playing around after a while the chain broke. When I started building engines and racing I made sure the timing chain was a little loose. I believe today you can get under size sprockets for non nylon type sprockets. By the way the Chevy nylon sprocket is 1/2 inch wide the 1958 Corvette was 5/8 wide.
Don
Cloyes makes different length setups for line bored etc.
Here's an interesting anecdote for you all, based on my build and repair experience of Caterpillar C15's...
The specificaton for harmonic damper/balancer replacement is 500,000 to 600,000 miles, depending on the application, and also specified by CAT to be done at leaking front seal replacement.
If not changed out at seal replacement, the seal will begin to leak again within a very short time, and it has nothing to do with the condition of the running surface of the damper where it contacts the seal as it's a two piece seal, where the inner part of the seal is a sleeve that rotates with balancer.
Furthermore, when the damper is changed, it improves the fuel consumption by approximately 8 to 10%, which is noticeable immediately after seal and balancer changeout, even when no other repairs to the engine are being performed.
The conclusion drawn to by myself and peer colleagues is, the damper is an accumulator of energy at the firing of each cylinder, and that, the elasticity performance of the rubber between the two damper parts deteriorates, and although it may not appear to be damaged or broken, on a micro level the bonding of rubber particle does become compromised.
I don't remember just how many hours John Deere also recommended changing the front pulley assembly also, It my have been only on certain models and applications.
Absolutely.
Yes much the same with 50, 60 litre + Cummins engines too
Also, if the damper rubber gets too weak, the damper can lay over to one side, creating a negative inertial torque moment which can not only rob power, but cause main journal failure and crank shaft cracking.
This has got to be an expensive maintenance repair. Could this have any effect on a V8 engine is my question.
No stone is left unturned. Great Videos!
I'm getting addicted to these tips. Thx DV
Every little bit adds up. Thank you David!
I would love your knowledge on fluid dampers vs fix weight dampers. Thanks for all you do DV!
Me Too
He did you want a heavy one ,not a light one back in the day they used 409 balancers on small blocks
@@darrellsomers5427 I’m talking about the Fluid filled dampers vs the all steel weighted with the rubber ring.
I was wondering the same, I think they have their limit within rpm, but I don't know. Only what I've seen on a chart , BUT those charts may be from a competitor brand and not quite truthful !
Way off the subject here but kinda interesting.... had a 327 chev that was pro built... always had very , very , slight harmonic vibration at different rpm's. That was with the high performance big 8" corvette balancer. Switched to the FluidDamper and eliminated all harmonic vibrations ! Sorry.. way off the main subject here but just thought I'd throw that out...
My experience from running too tight of a timing chain is that the front cam bearing wears in (i.e. excessive wear) before the chain and gears break-in. This makes sense since the cam bearing is much softer than the steel chain and gears.
As well as crank bearings, most already have a belt pulling on them, old Buicks need a very tight power steering belt heard many front main bearings slap before oil pressure, and they have weak pumps.
I experienced the same thing with a 2.2/2.5L mopar 4 popper.
It didn't have a automatic belt tensioner and everytime I set the tensioner too tight, it would break the cam after about 500 miles no sweat. Went thru 3 cams before I referenced the OEM service manuals and saw that I was goin too tight.
Set it to OEM spec and had no issues with the cam for the years after I had the car.
Interesting .. I would have never thought the power loss would be 11hp and the fact that the gear would be worn, that interesting as well. A loose timing chain was said to be caused by stretch and a worn gear contributed to the loose chain was never considered in my experience. I can't wait to see what other knowledge nuggets you have to share in the future.
More pronounced gear wear on the linkbelt style chains.
Thanks!
👍 This man's a living legend!
Thank you David, for sharing your knowledge.
If I recall, Grumpy Jenkins used stock nylon chain sets rather than double rollers. He said he put on a new set for every rebuild.
Light weight means less vibrations and they were cheap good for 50,000 miles on most small blicks
Okay
@@johnfairchild3421
'69 400 Pontiac... Mine went toothless in 36,000 miles. 10 miles from BFE. Used the best oil, and changes.
As always David thank you so much for sharing your vast knowledge!! Wish I’d known you when I was a young man. I absorb this like a sponge. My mind spins constantly pondering how to make things better!! Faster stronger!!
A frequently overlooked factor I’ve seen, is distributor gear backlash and the resulting chatter not only resulting in ignition scatter, but, crazy vibes being fed back into the camshaft.
I’ve also wondered if it may have contributed to oil pump issues.
They always put the oil pump on the end of the distributor shaft for the purpose of keeping the slop in the skew gears in check = of no effect. Also pretty sure the forces the camshaft deals with are about an order of magnitude larger than the oil pump+distributor forces so they can be neglected.
However when you go changing the valvetrain from stock and standard stuff then you really should figure out some sort of crank trigger system. The high voltage spark distribution function will tolerate a fair amount rotor-cap phasing error (as witnessed by every stock vacuum advance system introducing rotor-cap phasing error)(well - except for some old engines that turned the entire distributor = four main bearing Chevy Sixes)
But the problem with crank triggered stuff is how to come up with centrifugal advance = and even worse you need to keep a stock type centrifugal advance in the distributor = and they need to match to keep rotor-cap in synch !
Good luck - I never did figure out a good Old School Way to keep all the cam wind-up and wind-down from affecting ignition timing, I run a Pontiac and the stock water pump may have to go so I can cobble together some kind of ultra-short distributor run off the front end of the cam. It's a headscratcher.
@@stujones3566 Once I saw a magazine article where a guy took a V8 distributor and machined it to have little sealed ball bearings in it instead of engine-oil bushings. He laid it down and faced it back along the block and made brackets to hold it and allow for timing adjustments. Finally he machined a little cog-belt pulley and got it on the crank snout behind the harmonic balancer. Finally he put a twice-as-big cog pulley on the drive end of the distributor (to get the 2-1 geardown).
It worked great on a dragster but real car engines have a crossmember and engine mounts down there on both sides.
Sure would be fun getting under it to change points, have oil dripping on your ignition, and making a cover to keep sticks and stones out of your belt drive !
So the search goes on . . . I am really starting to envy guys whose engines drive the distributor off the FRONT of the camshaft (but hey their oil pump has to suck oil from the where it's all glued to the back of the block by acceleration - up to their front mounted oil pump.)(gah - seems like there's no easy solution!)
The farm boy in me says you can probably stretch a tight chain? I totally follow your logic on how this could affect horsepower. Thanks for the tip
Thank you for this knowledge sharing, I would not have thought of this remarkable loss. If timing gears are used instead, have you Dyno tested timing chain vs a timing gear setup? Again, I really appreciate how you use your time to share your extensive experience with us.
It’s not just friction with an initially tight timing chain. As the chain spins faster it flings out from the cogs a little bit and gets even tighter. Thanks brother!
WHAT i've found is that tight timing chains will rub the bottoms of the cam bearings and reduce the effectiveness of the hydrodynamic lubricating wedge and literally eat the bearings causing a lot of unnecessary bearing scrub,timing chain components have to be matched to the load put up on the vehicle ,in racing,constantly changed,everyday driving,every 85 to 125k or the retarded timing with eat the exhaust valves and seats right out of the head,DAVID IS THE ONLY ONE WHO HAS EXPLAINED THIS PROBLEM perfectly,this is the man who has been there,learning BY DOING,thanks DAVE
Fantastic. Can't wait to see this episode come online.
I’m building my first small block Chevy in 37 years right now working with a very reputable machine shop owner. Excited to see how it goes. Thank you David
My 5.7 LT1 has over 170k miles so I'm gonna try to do a mild rebuild/refresh. A timing set is on my list. I will definitely remember this information. And Cloyes is definitely the brand I'm buying
Wise words excellent channel and thank you, words of experience and I never looked at it like that, and your right the gear teeth wear as well, I checked with a new chain it was loose as the old chain same original block not line bored so now am going to buy a set with new gears and use my old chain and see thank you I subscribed cheers from 🇦🇺
Great information again, thanks for sharing, all the best to you and your loved ones
ALWAYS GREAT CONTENT THANKS DAVID
The linkbelt timing chains wore like the devil. A guy I worked with used to say when doing a tuneup, if the timing chain had any more than 30k miles you needed to replace it. Without doing so he said, you could never get the engine to run 100%. To a point he was correct but a little anal about it. My experience was 50k to 60k was kind of the wear limit. Now we need to realise oils and metalurgy were not what we have today. For long life a truroller timing set is the answer as they will generally go 100k miles or more.
You can rotate the crankshaft forward and backward to just take up the timing chain slack to get an idea of the state of wear without removal of the timing cover.
I read this back in the 80s in hot rod I believe it also mentioned something about changing the cam timing at higher rpms
Interesting,
looks like the same as for a chain on a chainsaw.
I think its more friction inside the chain between the links moving amongst each other.
I always use a Mopar Timing Chain Tensioner, and my timing is always Spot On.
Oops! That was a shorty. Well done. Thank you. Looking forward to the next episode.
ps: hopefully you read my comments. May be you can answer some of them in a new episode (?). Thank you.
on 10:30 great info how many tension the timing chain really needs
I definitely see where the pressure against the bearings and resonant crank harmonics can both cause massive power loss.
Another thing besides simple friction, there is also dimensional harmonic throw, and resultant lifter knocking and lifter drop.
In other words,
1: the vibrations from the crank CAN cause the cam to flex [imperceptibly to the naked eye, but with a really close up high speed camera you could see it] and this can both cause the rotating mass of the cam shaft experience centripetal rotational resistance because of the laws of conservation of momentum, which, by its nature, creates moments of negative torque, which travels back to the crankshaft, and stealing that torque from the entire system.
2: this flexation will cause the cam journals to impinge upon the cam bearings more, pushing through the layer of oil, causing them to potentially collide with the bearings, not only adding friction, but causing wear.
3: the same flexation will change the 'effective' cam-to-lifter contact, meaning that at unreliable, and irregular intervals, the lobes will be either further out [causing increased lift] or further in [causing decreasing lift]. While this may not seem very important 'as long as it all averages out in the end', it in fact is VERY important, as it leads to INCREASED harmonic IMBALANCE in the crank shaft, potentially leading to an infinite feedback loop and the destruction of the engine at an accelerated rate, and robs all engines of total horsepower when they are fed an imbalanced volume of air and fuel mixture.
To clarify point 3-B, when cylinders deviate from a uniform output level, this not only increases vibrations, and crank shaft stress, it also brings the average BELOW even the lowest cylinder value, therefore bringing the total net collective value down.
This is something that was proven back as early as the 1930's when early race cars were being experimented on and they were being built with substandard parts, but was soon forgotten because racing engines were eventually going from hand built individual creations to products of a uniform engine manufacturing system which reduced these irregularities a lot, AND where both total horsepower and engine speeds were quite low, as compared with today's modern engines.
The facts were always there, but they were forgotten because of the development curves in the industry, where high engine speeds and lower displacement engines where the effects are more pronounced had not really come into existence yet.
As one perfects an engine, they can expect to run into new, or, more correctly, little known issues which few people ever wrote about very much.
For instance: one of the best possible ways to prevent this kind of whipping of a camshaft, just like with crank throws on a high performance engine, is to increase the barrel thickness of the cam while boring it out hollow.
As a 'drilled' or 'bored' cam, you can maintain the same total mass, and same total volume of metal, but with a stronger, more rigid form, so that it will be much less prone to whipping.
That does not remove the need for proper cam chain tension, but it will greatly improve it.
Also, hollow-grinding all of the cam lobes would help a lot as well, but that is some really high end machining!
All of this is making me think perhaps I need to be building a new kind of cam shaft.
Smokey Yunick had cams ground backwards so he could run a single gear timing gear drive like a 300 Ford 6. He recommended a 4-7 swap reverse rotation cam with a single gear to gear set chainless, like a Ford 240-300 6.
GMs inline 6 engines also had gear to gear timing and it would have been awesome if they would have kept it on the v8s!!
David, please talk about the pros and cons of a belt driven timing chain versus a chain
They've got their place, I've got a newfound respect for belts.
About a month ago, I replaced a broken belt on a 2.3 ford that powered a generator.
It was an early 80s model ,with 1700hrs on it and was the original belt.
Gotta love non-interference engines, and I wonder if the new belt will last another 40yrs.
@@MrTheHillfolk what sparked my curiosity was David mention a loose chain, dampen more vibrations to the crankshaft and camshaft, and I believe a belt being rubber with dampen it even more, and I’ve noticed Steve Morris engines, uses belts and not chains on his motors, but I’d love to hear David’s perspective
Maybe that's why timing gears in the 60s were neoprene and would only last 50-60k.
David: I’m a regular for info on the Uncle Tony 318 build info, we out here are blessed to be able to tap into what you have learned over the span of years that you have been doing this! I have always wondered about “ gear cam drives” the timing chain tension is interesting! Especially at my age of 75 having dealt with this problem with the many engines that I have built! Seems to me the more slop there is in the chain it would change your cam timing logically thinking, which is why we have an adjustable distributor whereas you can check the timing at the crank pulley! The tighter the timing chain the closer the relationship of everything to the designed running timing specification of the particular engine! Is my thinking correct!? So what about if it is set up with a gear cam crank set up? And what do you think of gear drives? I don’t think gear drives are available for Mopars regardless of that I’d like to know what you think about gear drives? Regards Mad Mike S. …….
Didn’t Smokey Yunick claim that the timing chain was the work of the devil?
LOL sounds like something smokey would say but I think it's a better system than a timing belt or an aftermarket retrofitted gear drive but oem gear to gear systems are usually pretty damn reliable and you can rev them to the moon as long as the valve springs can keep up.
@@rustybritches6747 the problem with gears is they cost more power than a proper sized chain. A belt ultimately costs the least amount of power. Friction is the loss. Gear drives by nature have more surface area in constant contact therefore loose the most amount of power. A gear drive keeps timing as consistent as can be though
@@jeremypike9153 maybe but I'm not worried about a few horsepower when I'm at 8000+ rpm, I rather have reliable valve train control
@@jeremypike9153wrong , good gear is 98-99percent efficient
I've also never liked the look of the chains with no tensioner or anything, always seemed like a halfassed solution that I'm surprised works as well as it does. I guess it may have made more sense when rings were soft iron and the engine overhaul interval of a typical passenger car was like 50k miles, you wouldn't be going in often just to change a sloppy chain in that world.
Thanks David , since I rebuilt my
SBC , I've had a problem with my distributor moving up in it's
slip collar.
This may be my problem.
Back in 1972 one of my first builds was a 283 chevy with a Cloyes three position crank sprocket it took several tries to get the chain and sprockets assembled. Remember that well. It might be with a line hone on the main bearing bores the chain would loosen up a bit.
Cloyes has always made different length timing sets for line bored engines etc
Big fan, thanks for the tips and the books. I read max hp big block on a budget and got a healthy engine on my hands now
Have you ever checked your cam timing from both banks? I was checking my cam timing on a hot rebuilt 1967 Buick 430. I adjusted the timing on the #1 cylinder as usual. I decided to verify the timing on cylinder #2, and it was 4 degrees off! It was 4 degrees late. I then proceeded to check all cylinders, and sure enough, cylinders 1, 3, 5 and 7 were the same, while 2, 4, 6 and 8 were 4 degrees late! I consulted TA-Performance who supplied the cam, heads and everything, and they suggested to split the difference between banks. I think this is due to sloppy machining of the lifter bores in the block at the factory.
Does that have anything to do with a built in 4° advance? My comp cam xe284 came with a 4°advance.
Power pirate 😂😂 my new favourite saying.. pure gold as usual 👌
I would suspect that timing set was mis packaged, probably intended for a block that was line bored excessively so the crank to cam spacing would be reduced leaving proper slack in the chain.
That being said, EXCELLENT information on all of your videos. Thank you for all that you share with us viewers! I'll be using a great deal of this info on my next sbc build!
Or just crappy QC, lots of tolerances to stack in a timing chain, without even getting into the finer points of gear/sprocket cutting.
Thank you David, great information.
What are your thoughts on gears instead of chain used to timing set?
I love that way back when knowledge
PERSONALLY I have always been a fan of floating gear type cam drives.
What about gear drives? Like the Pete Jackson gear driven timing gear sets, I have heard positive and negatives on them,
I can't say this is any proper test,but i ran a pete jackson gear drive in my 482 big block chevy from 1988 to 1998 and it was my daily driver in a 70 chevelle. using a .670 .690 lift roller with 312-322 advertised duration,13:1 compression,3.73 rear end gear. The car ran 10.60's at the track on weekends and was street raced excessively. In those 10 years the timing was dead rock steady and i never experienced issues from harmonics hurting spring pressures as some claim. that being said its critical to set the gears up correct for clearances. One persons account does not make a study,but i run gear drives in everything i have including a high 9 second tubbed 88 S-10 truck.
i'm wondering if an align hone of the bearing saddles on another block would help that tight timing chain get some slack if transfered over, due to the crank moving up towards the cam bearings in the second block
Any videos on gear driven cams? I like the Milodon 3 gear set up over the 4 gear dual idler types
The weak link I see on V-8 engines are chain drives. After 150.000 miles, most chains are shot. Most new engines are running tensioners. How do we feel about chain tensioners. AND Smokey Yunick was a big fan of gear drives
I was gonna replace the timing chain tensioner when I rebuilt my 4.2 Ford v6 then I took it completely off and saw there was no way it could possibly skip a whole tooth and put the old one back in it.been like that for two years now.
I notice.that too tight anything saps power, you may be miles before everthing in that block is friendly. Pop on new heads, +10-20 hp. Index your plugs, also my timing is always 1 tooth plus on the crank to take the mechanical advantage of the piston going down and not getting resistance from TDC to crank relation.
Thanks for another great video jam packed for of knowledge and experience. @DavidVizard in your porting series do you plan on porting any 4 valve heads? I need all the help I can get. Thank you
I wonder if an advanced oil formulation of MoDTC with a synergistic addition of ZDDP or MOLYVAN-855 in the oil which are advanced anti-friction components that work thru a plating-effect & if they could also dampen crank harmonics...
Thank you for sharing your knowledge with us , I’ve always wondered if gear drives are worth the supposed extra harmonics vs accuracy? That said I’ve a Jackson .005 allign honed set on a n/a 355 with 5 seasons of open wheel usage & now in a 2450 lb super gas car as a starter engine for kiddo & it ran 10.80 @122 w a set 461 heads i home ported & a flat tappet solid cam. I wonder if I should have used a chain , but it’s a reliable little mill , thoughts welcome 🙏
My thoughts are you should have gone with a Mopar, BUT that's my thoughts on everything. (AND NOT A THIRD GEN HEMI)
Sounds like a lucky kid to get to start out with a rig like that. 👍 It's been my own experience that DV has it right, belt drive is the pinnacle but I've used gears and never had a problem, though it was not a race engine, overkill just to talk about with my friends
the dog bone gear drives make a lot of bad harmonics. the single gears are great.
What about gear drive?? Was always told by the old racing guy that the way to go.
Pulled down this rebuilt engine that I got in a car for some upgrades and found that the timing chain was so tight, the front cam bearings had worn into the copper. Prob used the wrong set or it was packaged wrong But supposedly it didn't have a lot of miles on it and I believe that because it was a efi car that wasn't set up right at all. Not one sensor hooked up!
This makes me wonder if I should delete the timing chain tensioner on my 5.2 magnum 390 stroker motor. These engines have a longer timing chain than a small block Chevy because the camshaft set's higher up in the block. Those tensioners make the timing chain super tight.
Had to settle for 4th. Nailed the pole position on a few earlier in the week
Have to bring it up. What are your thoughts on Timing BELTS and GOLF BALL porting? Love your videos.
I have wondered if a chain uses less power than gear drives. I don't really like gear drive, but a zessel is not ideal for the street.
Ni
Can you buy timing chains with different lengths? I ask because sometimes, if the block is alignbored too much, you might have the other side of the problem.
I know one machine shop that created a dampener/tension device on an old Pontiac block to take up the slack. Sounds like they could have save a lot of time/effort with a proper length chain.
I also seem to recall a lot of discussion about true roller, vs. gear drive, vs. belt drive - where belt drive was the best on horsepower. Is that still the case?
Have a big block chevy race motor. It has been line honed maybe 3 times. Put it back together noticed a very slack timing chain. Ordered up cloyes new timing set up -.02 much better. Snug maybe 1/16-1/8 ? Roller cam . Now I'm concerned.
What about gear drives, do they pirate power more than a well setup chain and gears? Thanks in advance.
It's cool that Sammy Hagar helps out in your shop!
Would recommend gearsor a belt over chains then?
I’d like to ask the hp cost of a double row timing chain, and at what point do you have to use them, an ls runs a single, when would you have to double up.
Good question 👍👍
This is another reason that the manufacturers went to timing belts. The belt actually dampens the harmonics in the engine! The other one of course and belt material improved is cost and profit from maintenance!
Thanks David
You think these chains are being made tighter anymore to account for more engines getting line honed?
As a young boy in the early 80s every old motor I swapped a cam into had a pan full of nylon teeth off the timing gears. Those motors must have been making an extra 30 HP. lol
Minimum of 5 hp per tooth lol
You talked previously about a belt system being the best choice. Are belt systems readily available for most motors?
Thanks for another great video David
Is there advantage/ disadvantage in H.P by going with a belt over chain ?
David Vizard, a question....Would cam bearings that are tight enough that the camshaft (by itself) can only be turned with a wrench on the cam bolt, would that cause similar power loss numbers as too tight of a chain (less,more) ?
You mentioned vibration dampers (notice I didn't say "harmonic balancers"!). What STYLE and brand do you use? Surely there's power to be gained or lost there as well.
Thank you Sir
Makes me wonder what the cam timing is doing on my coyote, even though the vvt is deleted still alot of chains. Cam timing might be more of suggestion for my motor.
If you didn't delete vvt you would be able to have the ecu control it ( and see where it is)
Big Chief runs a European timing chain. I can't remember the name. It moves more freely than your most popular chains. He it running a Small block with Pontiac Nascar type heads alot of RPM and turbos.
Too tight of cam chain will eat the cam bearing as well. I have seen it with my own eyes. 20,000 mile engine that looked great except for the front cam bearing. Only noticed it because my friend was doing a cam change.
Wish you tried a belt or gear drive for difference
Is that adjustable timing gear for street use or just a tool for dyno testing?
Typically 'timing chain/gear' power losses are not from the chain/gear drive dragging and causing friction. It's from incorrect crank to camshaft phasing-related issues. In any engine, a few degrees of cam phasing in the wrong direction can easily knock fuel efficiency down by several percent or more in its primary operational RPM band.
Watch the video again. In each test the timing was optimized by virtue of the CC adjustable timing gear!
Aren't timing belts now the preferred method now? Even on V8's?
Ford uses chains on ohc v8s
What about using a timing chain dampener that constantly keep tension on the chain like most modern LS or LT gen V style? Better to delete or leave?
develop a timing chain break in aperatus, that employs valve grinding compoumd mixed with oil.
When you did the worn chain tests, did you run the worn chains on new sprockets or the sprockets the chain got worn on?
Broken-in chains on new sprokets.
So, besides parasitic loss from the crank (2-3 HP) with a relatively tight timing chain, I missed what other drivers were a possible factor aside from "the Dyno told me so"?
11 loss on 475 HP.
Thank you, one more bit of information, it may really help.
What are you’re views on timing gear drive setups like a Pete Jackson strait cut?
I used to use fluiddamper. Nobody uses them anymore. I thought they would work at a wider rpm range
An old friend of mine told me that horse power and toque hide in the details
Interesting ; thank you.
AFAIK there is really only one decent brand of timing chain. JWIS from Germany. And even they do not last very long before going slack moving cam timing. There is tight and excesivly tight though and that usually comes back to the gears being a touch too large,, or small.
I have had one of those chains break as well, was not peined properly and it disconnected itself. Under 5000 miles in a very mild 400 Ford.
THAT WAS GOOD, "GRANDPA", THANKS A LOT.
How about the torque numbers? Drag racers need torque.
So is a gear drive worse aka too tight & rob power vs a double row timming chain?
Gear drives need to be really good to better timing chains.
What break-in oil di you recommend. Flat tappet sbc or bbc
How did you go from 1/16 play to 1/8 play?