I'm not even in the same universe as this man, with what he's already forgotten. But I'm 60, and have built engines my entire life. A large family of racers has made some good life's lessons for me. One of the "big secrets" I learned early on, was cam CL selection, depending on the build. In the mid 70s, my first car was a 70 1/2 Z28, that you couldn't find gas to run. I built a flat top piston 355 with a 108 degree CL cam, and ported the 292 heads for it. I could run medium grade gas, and it would run circles around the pop up engine that it came with, even with race gas for it. One of the fastest cars around my little town, for a long time.
I appreciate all of your time spent on doing these videos . I remember reading articles in magazines that I think were written by Mr. Vizard and I was always impressed with the information . Very sharp guy
Thank you David! I’m really enjoying these videos! I’ve learned a lot of techniques that’ll help me with rebuilding my next engine. I’ve learned a few tricks, but you go much deeper into it. These are great tips to help make more power, and help with durability. I’m so glad you made these videos!!
Thank you for showing telling, and how to improve the video for the one’s that know not a thing about what improves the running of a motor.like if you port the heads and all ,what other you can do so on and so on.to improve the running of the motor, like more fuel more cam for opening the intake and air out.
Awesone stuff. "Someone" familiar designed a cam for me using solid roller lobe profiles from Comp, about 12 years ago. He took all my info (406 ci, max power at 6000, manual trans, 2800 lb, 25" tire, 3.7:1 gear, head flow, street and road course track day use) and spec'd a 105 LSA. The thing is a beast. Difficult to tune the carb at first, with all of that overlap, but this thing sings! If you see him around, thank him ;). Also, the new format is great!!! I like the improvements.
Ok, mr Vizard, almost everything you have said about rocker ratio confirms what I had always believed. Not only does fast off the seat give you more flow when you need it, but I believe it also gives the pushrods and lifters a break at their most stressed moments. After all, if you are fast off the seAt, it is slower over the nose for the same overall lift. What i want to know is how far can you take it if you optimize the ratio change of the rocker and the camshaft grind to go with it?
Wow!!! What perfect timing on this video. I just yesterday got into a discussion with my engine builder on this very topic. Thanks again Mr. Vizard for clearing this up for me. Again you are the best!!!!
Thank you David your research is and has been a reset for me. i was seen as a clever fellow at the strip. but actually not so much and had many established names that mislead or through ignorance taught me.I saw about a thirty-year-old seminar on mini-engines bored one night though I have no connection to them this 2-hour video showed me how wrong i was i enjoy being proved wrong cause I must have learned something to realize this since your simple application of physics have shown me more about engines than the previous 30 years and most of it you have been using as long or longer I hope to meet you one day I have been redesigning 4.6l 2v chambers with your theories and believe I am on to something i only used this type of head because of its terrible layout sarcastically developing you might say MIKE WALKER
I like to swap to 1.6:1 rockers, with atleast roller tips, especially with cams in the .460-550" range, in Street engines, I had a crane compucam, it was hyd roller, with .465" I don't rember much else about it, but it had about 10.2:1 compression, with trickflow twisted wedge heads, 355cid Chevy, it ran very nicely, loads of TQ, it had a Holley Street dominator intake ,dual plane! The cam lift is at 1.5:1 ratio, so add around .030" , seems it may been 452/465" at 1.5:1, but it was a very torquey and would rev to 6k and beyond..
Excellent video Mr. Vizard. Thank you. Is there a mathematical formula to roughly estimate the ammount in which the LCA will be effected by increasing or decreasing rocker ratio ? For example, in my 448ci Big Block Mopar I will be utilizing a cam with a 107° Lobe Seperation Angle [ I know too wide with my 2.14 valve per your 128 formula ].. but, if I increase from my Crane adjustable 1.5 ratio rockers to a set of 1.7 ratio PRW's can I calculate the ammount of overlap gained in degrees of rotation ?
Thanks David. I enjoyed the discussion and points you made regarding rockers and cam CL. Makes me wonder how a dual pattern cam is affected especially since you commented that fast open rockers were only changed on the intake side. Looking forward to whatever you put out next.
David question , IV recently came across a 383 sbc build that makes 580 ft lbs n 565 hp with brodix 23 degree heads air gap Mani , DNT no the cam came across many street strip 383 that do 600 hp n 545 tq with 1 3/4 headers , all I no that is different is he has 1 5/8 headers , is this the diff n power n tq ? help needed
Some years back that rifle would have been considered a decent shooter but the bar's definitely at a much higher level these days. I imagine you've sold more Rugar Americans than any one individual out there at your own expense so I was glad Rugar replaced it. 👍👍
If I heard correctly, David says overlap is more important for torque than intake closing is for horsepower. Otherwise a tighter LSA, which moves intake closing earlier, AND shorter duration, which moves intake closing earlier yet, would not let the engine’s power come out near the same.
For low budget people trying to attain good power can you give the name of a few after market companies for valve springs,lifters and cams and so on without getting into trouble.I’ve been down a few yrs with back problems just getting back at it and I can’t believe the prices since LS’s came in,aluminum heads and then zinc out of oil dove up prices on everything including anti freeze.it’s really getting hard to keep up.thanks for all your sharing,been using your books a long time
So it seems like the bigger the engine the tighter the lobe separation angle. That being said what should the lobe separation before a 545 in.³ big block Ford 10.2 to 1 compression 1.7 ratio rockers? Idk if they are 1.7 over the nose or off the seat. Wondering on the lift as well?
What about about say a small hyd roller cam which will have a slower acceleration off the seat? Would high ratio rockers help or would it cause the acceleration at the nose to be too fast?
Mr. Lizard I am a big fan and have all your books. I'm also a big grumpy jenkins, and smokey yunick fan as well. My question is what lsa/ ICL for a 406 - 427 sbc with 13.5 to 1 compression, 210cc AFR race heads with 2.08 intake valves, BMP motown intake or Holley Strip dominator intake, and a 950CFM quickfuel carb. I try using your chart that references a 104 LSA or ICL ( ICA) cam. Am I doing something wrong and what would be the right cam. I use Howard cams , Comp Cams and Lunati. Your help is must appreciated. A engine builder recommeded a comp cam 12-996-9 or 12-906-9 roller for my build.
Assuming a 427 ci sbc, that's 53.46 ci per cylinder. 53.46/2.08 equals 25.7. Referencing the chart in the book, 25.7 gives me a 103 lsa, which is good for a 10.5:1 engine. Compression ratio correction according to Dave's book is .75 wider for every ratio above 10.5:1. So 3 times .75 equals 2.25. 103 lsa plus 2.25 gives 105.25 of course. And don't forget, you may need to go wider still if you bump the rocker ratio any.
I don’t know how you are going to give us all the information you have. All the motor are not the same and you just showed that with the 355 and 383 . Good job trying to help out the little guy.
That's getting down to the wire there. David you are the man. This is how you really understand your motor. Higher lobe separation raises the torque peak.
My cam is 243 in 257 ex @ .050 , 107 LSA , lobe lift .355 in 346 ex , the engine is 355 sbc , flat top pistons , 64cc iron bowtie heads. Would 1.7 rockers be a good choice in this case, Thank you. .
Someone please set me straight on this. Is the LCA the angle between TDC & the centre of the intake lobe, or the angle between the centers of the intake & exhaust lobes?
TD and Jesel make pretty good stuff. Manton probably too (great pushrods). I like to press the roller bearings out and put in bushings to help eliminate failures. Bushings tend to be more forgiving in lifters and rockers. It takes essentially nothing in diameter difference of the needles, the load is concentrated on the larger one and when it comes apart ya get ~ 0.300" lash, needle bits everywhere and there goes your engine.
I will say to a point on my big and small blocks a 106-108 lsa on a street engine, i could run a little bigger cam. To a point! I would still get similar Intake closing points after TDC a cam or two smaller on a wider LSA calculating it. This helped a lot. Although some vacuum went on idle , OFF IDLE TO MID RANGE TORQUE IMPROVED. and i was not running high compression on some of these. In fact notably too low. But built amazing torque on the steet. This was all from reading his books growing up as a kid, i jumped to ording cams like ground like this Im not always big on the tight LSA anymore. But it will wiake up mid range power in many cases, but i say to a point because its also not a band aid for the wrong cam.
I've seen guys use wider LCAs than I'd think were appropriate, run a hell of a lot of advance and extra exhaust duration. SB2 stuff. They won races but I'd consider some changes.
This video has allot of meaning for all us 350 owners with the Chevrolet Performance 14097395 cam (109 lobe separation). Thanks Mr. Vizard! Looks like I need to spend money on new rockers now...
I'm wondering if I could increase drivability on my SBF that is fuel injection by swapping the TFS stage 2 cam with compcams magnum 1.6 for a stage 1 cam with 1.72 rockers on the TFS 11r 190 cnc heads.
I guess if you only use higher ratio on either intake or exhaust the change in lobe center will be less? As for improvement to the channel it would be interesting with some 4 and 6cyl talks. Like are there differences in how to size valve dimension, how they respond to cam changes, rocker ratios, exhaust tuning etc? And maybe put it in relation to v8 stuff seeing how most of the info out there are for v8 stuff
@@marvingvx1 my apologies, I meant to say 250 hp max with a progressive controller. Max power with nitrous . It's a 2 bolt main block which have more meat in the webbing. Was thinking about a short fill to the freeze plug with hardblock
@@marvingvx1 I have a set of Dart Iron Eagle 215 heads with cleaned up pockets and ports utilizing techniques from your books but I am considering a set of similar heads from Flotek in aluminum.
David, what is your take on dual ratio's? If I use 1.5's on the intake and 1.6's on the exhaust would that help scavenging or would there be a conflict? I have read where some run the dual setup but don't see any dump numbers. Thank you for these fantastic videos.👍👌✌️🤙🏻
Mr. Vizard the Wizard, I’m hoping for a little clarification. When you say lobe centerline angle, are you referring to the intake lobe centerline angle or the lobe separation angle? Thanks for sharing your wisdom and experience!
I'm not even in the same universe as this man, with what he's already forgotten. But I'm 60, and have built engines my entire life. A large family of racers has made some good life's lessons for me. One of the "big secrets" I learned early on, was cam CL selection, depending on the build. In the mid 70s, my first car was a 70 1/2 Z28, that you couldn't find gas to run. I built a flat top piston 355 with a 108 degree CL cam, and ported the 292 heads for it. I could run medium grade gas, and it would run circles around the pop up engine that it came with, even with race gas for it. One of the fastest cars around my little town, for a long time.
The 292 was sure a great head!
The last of the great pioneers in motorsports. David has forgotten more that most of us know about building engines
Had a hydraulic cam spec'd by David's cam program years back. For a 400 sbc, street-strip. Great results. He knows what he's doing. Thank u David.
I appreciate all of your time spent on doing these videos . I remember reading articles in magazines that I think were written by Mr. Vizard and I was always impressed with the information . Very sharp guy
Thank you David! I’m really enjoying these videos! I’ve learned a lot of techniques that’ll help me with rebuilding my next engine. I’ve learned a few tricks, but you go much deeper into it. These are great tips to help make more power, and help with durability. I’m so glad you made these videos!!
Thank you for showing telling, and how to improve the video for the one’s that know not a thing about what improves the running of a motor.like if you port the heads and all ,what other you can do so on and so on.to improve the running of the motor, like more fuel more cam for opening the intake and air out.
Awesone stuff. "Someone" familiar designed a cam for me using solid roller lobe profiles from Comp, about 12 years ago. He took all my info (406 ci, max power at 6000, manual trans, 2800 lb, 25" tire, 3.7:1 gear, head flow, street and road course track day use) and spec'd a 105 LSA. The thing is a beast. Difficult to tune the carb at first, with all of that overlap, but this thing sings! If you see him around, thank him ;).
Also, the new format is great!!! I like the improvements.
Sir David is horsepower royalty!
Ok, mr Vizard, almost everything you have said about rocker ratio confirms what I had always believed. Not only does fast off the seat give you more flow when you need it, but I believe it also gives the pushrods and lifters a break at their most stressed moments. After all, if you are fast off the seAt, it is slower over the nose for the same overall lift. What i want to know is how far can you take it if you optimize the ratio change of the rocker and the camshaft grind to go with it?
DV is the man!!!
Wow!!! What perfect timing on this video. I just yesterday got into a discussion with my engine builder on this very topic. Thanks again Mr. Vizard for clearing this up for me. Again you are the best!!!!
Thank you David your research is and has been a reset for me. i was seen as a clever fellow at the strip. but actually not so much and had many established names that mislead or through ignorance taught me.I saw about a thirty-year-old seminar on mini-engines bored one night though I have no connection to them this 2-hour video showed me how wrong i was i enjoy being proved wrong cause I must have learned something to realize this since your simple application of physics have shown me more about engines than the previous 30 years and most of it you have been using as long or longer I hope to meet you one day I have been redesigning 4.6l 2v chambers with your theories and believe I am on to something i only used this type of head because of its terrible layout sarcastically developing you might say MIKE WALKER
I like to swap to 1.6:1 rockers, with atleast roller tips, especially with cams in the .460-550" range, in Street engines, I had a crane compucam, it was hyd roller, with .465" I don't rember much else about it, but it had about 10.2:1 compression, with trickflow twisted wedge heads, 355cid Chevy, it ran very nicely, loads of TQ, it had a Holley Street dominator intake ,dual plane! The cam lift is at 1.5:1 ratio, so add around .030" , seems it may been 452/465" at 1.5:1, but it was a very torquey and would rev to 6k and beyond..
Excellent video Mr. Vizard. Thank you. Is there a mathematical formula to roughly estimate the ammount in which the LCA will be effected by increasing or decreasing rocker ratio ? For example, in my 448ci Big Block Mopar I will be utilizing a cam with a 107° Lobe Seperation Angle [ I know too wide with my 2.14 valve per your 128 formula ].. but, if I increase from my Crane adjustable 1.5 ratio rockers to a set of 1.7 ratio PRW's can I calculate the ammount of overlap gained in degrees of rotation ?
Thanks David. I enjoyed the discussion and points you made regarding rockers and cam CL. Makes me wonder how a dual pattern cam is affected especially since you commented that fast open rockers were only changed on the intake side. Looking forward to whatever you put out next.
David question , IV recently came across a 383 sbc build that makes 580 ft lbs n 565 hp with brodix 23 degree heads air gap Mani , DNT no the cam came across many street strip 383 that do 600 hp n 545 tq with 1 3/4 headers , all I no that is different is he has 1 5/8 headers , is this the diff n power n tq ? help needed
Some years back that rifle would have been considered a decent shooter but the bar's definitely at a much higher level these days. I imagine you've sold more Rugar Americans than any one individual out there at your own expense so I was glad Rugar replaced it. 👍👍
Awesome
Hi from Australia! Could you please get into the weight of rockers as well as tensile strength and maybe the balance of of them.
Thanks.
If I heard correctly, David says overlap is more important for torque than intake closing is for horsepower. Otherwise a tighter LSA, which moves intake closing earlier, AND shorter duration, which moves intake closing earlier yet, would not let the engine’s power come out near the same.
Great stuff! Any chance we could get Billy Godbold on here and talk lobe profiles, valve train control, spintron lessons and what's new?
That would be a great episode, could be a series.
For low budget people trying to attain good power can you give the name of a few after market companies for valve springs,lifters and cams and so on without getting into trouble.I’ve been down a few yrs with back problems just getting back at it and I can’t believe the prices since LS’s came in,aluminum heads and then zinc out of oil dove up prices on everything including anti freeze.it’s really getting hard to keep up.thanks for all your sharing,been using your books a long time
How does turbocharging effect ideal LSA?
So it seems like the bigger the engine the tighter the lobe separation angle. That being said what should the lobe separation before a 545 in.³ big block Ford 10.2 to 1 compression 1.7 ratio rockers? Idk if they are 1.7 over the nose or off the seat. Wondering on the lift as well?
If the openning acceleration of the valve is increased by the rocker arm doesn't it need stronger springs to maintain the valve in control?
DV did a good vid on beehives, etc.
Yes it does unless the originals were over stiff. Beehives cope with higher rstio's without much problem as they are very stiff over the nose.
Most small block chevy cams I've looked at are ground on 106 love centerline, big blocks 110 to 112
106 is about perfect for a 10/1 383
What about about say a small hyd roller cam which will have a slower acceleration off the seat? Would high ratio rockers help or would it cause the acceleration at the nose to be too fast?
Mr. Lizard I am a big fan and have all your books. I'm also a big grumpy jenkins, and smokey yunick fan as well. My question is what lsa/ ICL for a 406 - 427 sbc with 13.5 to 1 compression, 210cc AFR race heads with 2.08 intake valves, BMP motown intake or Holley Strip dominator intake, and a 950CFM quickfuel carb. I try using your chart that references a 104 LSA or ICL ( ICA) cam. Am I doing something wrong and what would be the right cam. I use Howard cams , Comp Cams and Lunati. Your help is must appreciated. A engine builder recommeded a comp cam 12-996-9 or 12-906-9 roller for my build.
Assuming a 427 ci sbc, that's 53.46 ci per cylinder. 53.46/2.08 equals 25.7. Referencing the chart in the book, 25.7 gives me a 103 lsa, which is good for a 10.5:1 engine.
Compression ratio correction according to Dave's book is .75 wider for every ratio above 10.5:1. So 3 times .75 equals 2.25. 103 lsa plus 2.25 gives 105.25 of course. And don't forget, you may need to go wider still if you bump the rocker ratio any.
You sir are an engine builder, most of us, engine assemblers, lol.
And some not very good at that LOL
Been telling customers what you are talking about for years.Work for Smokey, Summer when I was 14 79 now
I don’t know how you are going to give us all the information you have. All the motor are not the same and you just showed that with the 355 and 383 . Good job trying to help out the little guy.
Have you spoken about "Rev Kits".?
No --- but I guess I should though.
That's getting down to the wire there. David you are the man. This is how you really understand your motor. Higher lobe separation raises the torque peak.
My cam is 243 in 257 ex @ .050 , 107 LSA , lobe lift .355 in 346 ex , the engine is 355 sbc , flat top pistons , 64cc iron bowtie heads. Would 1.7 rockers be a good choice in this case, Thank you.
.
Someone please set me straight on this. Is the LCA the angle between TDC & the centre of the intake lobe, or the angle between the centers of the intake & exhaust lobes?
This channel is dead for now, find his other channel here: www.youtube.com/@DavidVizard
could you explain whose rockers are better than others
TD and Jesel make pretty good stuff. Manton probably too (great pushrods).
I like to press the roller bearings out and put in bushings to help eliminate failures. Bushings tend to be more forgiving in lifters and rockers. It takes essentially nothing in diameter difference of the needles, the load is concentrated on the larger one and when it comes apart ya get ~ 0.300" lash, needle bits everywhere and there goes your engine.
Could you talk about wide LSA cams in sbc engines? There are quite a few ground on 114°.
I will say to a point on my big and small blocks a 106-108 lsa on a street engine, i could run a little bigger cam. To a point! I would still get similar Intake closing points after TDC a cam or two smaller on a wider LSA calculating it. This helped a lot. Although some vacuum went on idle , OFF IDLE TO MID RANGE TORQUE IMPROVED. and i was not running high compression on some of these. In fact notably too low. But built amazing torque on the steet. This was all from reading his books growing up as a kid, i jumped to ording cams like ground like this
Im not always big on the tight LSA anymore. But it will wiake up mid range power in many cases, but i say to a point because its also not a band aid for the wrong cam.
114°? Hmm smallish cube, real high rpm 9° big valve stuff or certain turbo/nitrous engines perhaps?
I've seen guys use wider LCAs than I'd think were appropriate, run a hell of a lot of advance and extra exhaust duration. SB2 stuff. They won races but I'd consider some changes.
This video has allot of meaning for all us 350 owners with the Chevrolet Performance 14097395 cam (109 lobe separation). Thanks Mr. Vizard!
Looks like I need to spend money on new rockers now...
I'm wondering if I could increase drivability on my SBF that is fuel injection by swapping the TFS stage 2 cam with compcams magnum 1.6 for a stage 1 cam with 1.72 rockers on the TFS 11r 190 cnc heads.
William, give me the cam specs and I will tell you.
@@marvingvx1 stage 1 cam lift .499/.510 duration at .50 221/225 lobe sep 112, stage 2 cam lift .542/.563 duration at .50 224/232 lobe sep 112. Stage 2 cam timing intake centerline 107 and, exhaust centerline 117 btdc, +5 advance
I would think the extra lift would offset any lobe angle problems.
LSA is scavenging
A cam charactoristics mistake is a mistake no matter what but if faster off the seat the answeer is yes.
Thanks David. 50 years now, but still ref to my copy of tuning the A series, which I imagine is more then 30 years old?
I guess if you only use higher ratio on either intake or exhaust the change in lobe center will be less?
As for improvement to the channel it would be interesting with some 4 and 6cyl talks.
Like are there differences in how to size valve dimension, how they respond to cam changes, rocker ratios, exhaust tuning etc? And maybe put it in relation to v8 stuff seeing how most of the info out there are for v8 stuff
So what do I need for a 406 SBC with good heads, 10.5 comp, tunnel ram and nitrous? Street/strip with 4.10 gears
Nitrous jets what size? Do you want max output with or without the nitrous? What has been done to the block to prevent breakage if factory 400 block?
@@marvingvx1 my apologies, I meant to say 250 hp max with a progressive controller. Max power with nitrous . It's a 2 bolt main block which have more meat in the webbing. Was thinking about a short fill to the freeze plug with hardblock
@@marvingvx1 I have a set of Dart Iron Eagle 215 heads with cleaned up pockets and ports utilizing techniques from your books but I am considering a set of similar heads from Flotek in aluminum.
David, what is your take on dual ratio's? If I use 1.5's on the intake and 1.6's on the exhaust would that help scavenging or would there be a conflict? I have read where some run the dual setup but don't see any dump numbers. Thank you for these fantastic videos.👍👌✌️🤙🏻
Mr. Vizard the Wizard, I’m hoping for a little clarification. When you say lobe centerline angle, are you referring to the intake lobe centerline angle or the lobe separation angle? Thanks for sharing your wisdom and experience!
He's saying LCA is LSA, not the ICL.
👍💪
Cams too Small