350 LT1 or LT4 HEADS ON 4.3L L99? WILL THEY FIT?
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- Опубліковано 10 лют 2025
- HOLE SAW FOR DISTRIBUTOR, FLOWING INJECTORS, L99 CYLINDER HEAD FITMENT. DID I REALLY TAKE A HOLE SAW TO THE STOCK L99 (LT1) INTAKE MANIFOLD SO I COULD SLIDE IN A DISTRIBUTOR? CHECK OUT THE FANCY MILLING-AND THE GOBS OF SILICONE (YOU CAN't SEE) TO PLUG THE PASSAGES. ALSO FLOW TESTED THE STOCK INJECTORS-GOOD THING! CATCHING A PROBLEM BEFORE IT HAPPENS IS ALWAYS GOOD! WILL THE BIG-VALVE LT1 HEADS (DESIGNED TO FIT THE BIGGER BORE 5.7L) FIT IN THE SMALL-BORE 4.3? WE CHECK FITMENT WITH OUR BORE FIXTURE!
Glad to see someone is playing with this...I have an L99 I pulled the crank from to make a 302 LT1...wanted to do something with the remains of the L99. I have an old Accel LT1 tuned port intake base and a superram, I was thinking of making something with it. Just because I have the parts lol
It would be hilarious to drop that into an S10 that had a 4.3 v6...then tell people when they ask that it has a 4.3 LOL
Could also do a 305 or a 334 with it too.
God bless you Richard Holdener. You are doing the hotrod community a great service. Love the fact you've been doing so much 23° SBC stuff
I salute you Richard. The skill it takes to properly drill a distributor hole in a non distributor manifold and not have binding and miss matching problems is a testament to your skills as an machinist.
I did not drill the hole-it was done by hand-I just did the massaging
@@richardholdener1727 hey Richard how about putting gen 2 LT1 heads & intake manifold on a sbc (350) because they are cheap and I see them at the Pick A Part all the time
Not a Chevy fan but I AM a fan of motors!! Love your exercises of checking, re-checking, making something, grinding something, milling something.. You are awesomely crazy!!!
Thank you for your dedication to the pursuit of information!!!!
I see the mention on AMC. The one I'd like to see a pro like yourself tackle is a small bore/small valve 304. So many of these get dumped because of this and I. Believe they can run, isn't too many go overboard in the wrong direction.
I still drive a stock 360 and raced a 401 for years.
All of us watching what Richard does seriously need to give him a big round of applause and many rounds of sincere thank you's for doing all this testing. I have been doing this hot rod thing for a long time and you have to be really enthused in this to spend so much time and effort on providing us this knowledge. I especially admire the work on getting the distributor to fit and work correctly. I also do some things like this and you just hope it'll work when you're done but you use your good engineering skills to make it happen. Richard is great at doing this stuff. He's a real pro and extremely knowledgeable and I for one appreciate his efforts.
There is a 1xCam sensor and 24x crank sensor available for the LT1, ditch that hacked up distributor. Run coil on plug LS coils.
you pay for them... he'll use them
1997 Pontiac Comp T/A Owner Here, Upgrading to a 0411 ECM and Later a TH 24x system were the best 2 mods I ever did to my 50K original miles LT1. Owned the car since 2007 (2nd Owner) and put every bolt on under the sun including a Moser Rear End with 4:10's. When I completed my head and cam swap (CC503/LE2 Heads with 1.6 RR) in 2011. Not a single tuner could get her to break 400 WHP through my T56 (Around 389whp if it was a clean run on a good day). Once I went 0411, I hit 402 WHP but was always fighting ignition breakup around 4500rpms all the way through to 6300rpms. (Had the issue even with the old ECM after the cam swap. Once I installed the TH 24x kit problem was gone and hit 412 WHP on the Dyno. Now I cant decide if I want to keep stock cubes build the bottom end and go FI or just stay NA and go Golen 383
The 0411 ECM or any Aftermarket ECU for that matter opens up and allows someone to fine tune things so much better then the old system. The main reason for going 0411 was ease of tuning and the fact that the last tuner in my area who still did LT1 stuff actually quit doing them because it was always such a pain in the ass.
this would be the ticket!!!
Right! For dyno work, an external 24x reluctor is fine. Even a stock crank one popped off, pressed on a lathed disk with the pulley pattern. The first aftermarket setups were similar.
@@666BloodEagle I have the 24x reluctor wheel that I am not using. I will donate it if others will donate the rest.
Thanks for doing some LT stuff everyone seems to talk bad about these engines but they do make great power.
They only talk shit about them bc of the optijunk. The motors themselves were great but the ignition system really killed them
Only real "problem" is a lack of aftermarket blocks for making serious power imho.
@@Matt_Lanzer_13 I will never replace another optispark again.
@@b.c4066 the block issue may be solved in the very near future :)
@@b.c4066 it’s an iron block you don’t need an aftermarket block to make well over a thousand hp🤷♂️
Over 110 000 thousand Subscribers.
Well done Richard. 👍👍👍.
Many thanks!
Loving the great info here! These engines never got a fair shake. They're like the forgotten bastards of the SBC world. All stuff I wanted to do, but never found the time.
Really excited to see the stock TPI - cool that the mods to mount it are minimal. Very cool idea.
I really enjoyed this video presentation and so look forward to what you bring next
I built a MO code 68 302 back in the day, knife edged & lightened up stock forged crankshaft, BME aluminum rods, Arias custom pistons, 13-1 compression, Ultradyne 680 lift, 288@.050, 106 lobe separation solid roller, heavily ported phase 2 Bowtie heads, ported Holley Strip Dominator intake, 2 inch spacer with a 830 Holley Doublepumper, Mallory unilite distributor, 1 7/8 primary 3 1/2 collector Stahl headers, 6500 stall and a spooled 6-17 geared Dana 60. It went 9600rpm on the shift and 9800rpm thru the lights. It was in a 71 Vega.
Do people build those just cause they can it seams like a alot of money spent in special or highly modified parts and balancing
@@kevinjohnson9372 that's the way it was back in the day. Ya had to get creative. And back then, those core engines were still available pretty cheap. My dad raced several NHRA Modified Production Camaro back in the 70s. They raced on a pounds per cubic inch rule, depending on what class ya picked. So small cube engines in light cars are more durable than a big engine in a heavy car. At 10lbs per cube, to run a 400inch engine, you'd have to weigh 4000 lbs. A 300 inch engine in a 3000lb car is a better setup. Much easier on parts.
That thing must have sounded incredible!
@@IronChief lumpy as hell, it was unusually loud too. I have a rowdy 496 now that don't sound nothing like that thing did. All my non gearhead friends thought that Vega must have had a giant engine in it.
Richard is a true EFI MAD Scientist lol, love it!
Dont be too rough on us who choose to grind cast iron heads. The first port of call is always to optimize what is there. No disrespect to buying great aftermarket heads and supporting our industry who take a risk everytime an aluminum head is cast. Porting iron heads is harder than adding a turbo...but those of us who have done it can always control the valve shrouding, curtain area and seat quality. All US iron heads after 1972 are good quality and there is great info from okd guys who are prepared to share. I cut my teeth on Clive Tricky and David Vizard. The USA has the best head porters in the world. Foreigners like me learn from foreigners who learn from US guys who port heads. There is 80 hours of work porting two V8 heads. One wet and dry vac cleaner and a manameter, and a set of 205 cfm stock heads can become 300 cfm. The Chevy heads are the easiest heads to port.
I have nothing but respect for hard core guys who grind on iron heads-that's serious work-you guys are better men than me
Porting iron or alum each has their pros & cons, from my limited experience. I end up with lots of time into either or maybe I'm just slow LOL
Rumor has it the right combination of iron head on an iron block with hold down the most boost
Nothing wrong with iron heads. Our 3800 still used iron heads. 1000hp wasn't too hard to achieve. Lots of people made power with iron before alloy came along.
It's certainly a skill, but why bother doing this into iron heads
Lol my dad told me a story about an old panel truck he passed way back when he was young and thought he was invincible. The panel truck caught up to him and he was rolling about 100- stock old panel trucks don’t go that fast. They both pulled over for gas at the same station. Come to find out the panel truck had a big Caddy motor in it and was loaded with potatoes. He said if I didn’t have all those potatoes I think I could have passed you back. Dad said he didn’t argue because he wasn’t loosing him only the guy didn’t have enough room to pass. Nowadays that kind of tomfoolery will get your license pulled but back then people were just goofing around and letting off steam, of course there were less people on the road and it was still a dumb thing to do even then. Which is why he told us so we didn’t have to make all the same mistakes he did.
Thanks. For the intake. Comparison of the different. Tuneports
I HAD A 1977 formula sunbird before that i stuffed a n sbc 400 from a 3/4 ton van..,it had vortech heads and was so sick! ran low 12s all day long...car made 400plus hp,,miss that car, very rare now.,
I read an article years back about the distributor swap . Real cool . Like 2’off
Taking the kids to school with this one Richard :) I knew all this stuff, but its the geek in me that smiles as you expose it to the masses lol
For a 24x setup, you should be able to use a distributor from a Vortec 5.7 for the 1x cam signal. EFI Connections does make 24x crank triggers that would fit behind a stock 96-97 LT1 timing cover. If you put the motor in a car, you would just need to use a 96-97 hub for pulley alignment.
Really looking forward to the 302 LT1 build....
Keep this LT1 stuff going.. New to your channel and this is the content that linked me here, also why I immediately hit the Sub after i watched it all.
The coolant passages normally for the head to intake on a sbc is located just below head to block on lt1s. If you run lt1 heads on your sbc make sure you plug those ports as it will dump coolant into the valley.
LT1 heads have no coolant passages for intake exit
I’ve never done it before, but I’ve seen it done. I think you have to drill the coolant ports for the intake and plug the ports to the block, then you have to run an intake like the tpi on that you’re milling down to fit the lt1. A lot of work, but if you have a machine shop and time, you can have a decent set of heads. Random question, would you do the work to run the lt1 head on a sbc or buy a set of speedmaster as cast heads?
I had a 305, that I thought was a 350 until I pulled it out, it ran awesome for a 5 litre!
The L99 i pulled apart had a short skirt flat top 2 valve relief with lightweight narrow rings . Cant wait to see what the final numbers are on the 4.3
I really enjoy the work your doing,just subscribed.I at some point want to dive into a gmc typhoon 4.3 vortech engine for tons of reasons and I thought I'd bring it up as a performer in every day use instead of racing but enhanced lol,Love the tests & the everything your doing cool channel. Definitely giving me awsome tips when I start tinkering around lol.
Just do a LU3
Do you have a Typhoon already? Check out sytyregistry for some good info.
Another unique feature LT1 L99 crank, rods, intake(with mods) and such work on l98 and Lt4 HOT cam is super for l98street engines
A day with Richard and engine talk with adult beverage. Awesome time!
Good call on the heads. 1.94 valve will be plenty big.
We ran a 305 with early camelback heads that had 1.94/1.5 valves and a Comp 268 flat tappet cam. We had a valve shrouding issue and could not get the RPM over 4800 with or without a load on it.
That head has me a little worried I won't lie. That looks close enough that it could be sligntly off from cylinder to cylinder. You're going to have to turn that over by hand to see if you still have clearence after it's bolted down. Inconsistancys between castings and tollarances might mess you up. I'm trying to be optomistic but that's prettty close. If it works it will definatly take a bottle neck out of the airflow. This is getting fun!
Chevy actually put 4300 as a casting number on the bellhousing part of the block to distinguish it from the 4.3 V6.
A 5 or 6 speed behind the 6 cylinder would be awesome, I swapped in a 4 speed, behind one it was an amazing difference in performance!
I love this 😁. I had no idea that I wanted a 4.3 v8
Love the LTX content, great work!
I can’t wait to see the flow numbers of the stock LT4 heads vs LT1. Can’t find any data on it.
How. About taking the crank from the looks and use it in a lt1 block, build a short stroke big bore and. You can use. Either head,,. Enjoying your. Videos
I had an L 99 which has the same bore and stroke as the original 265 chevy engine, BUT ,BEWARE the rods are 5.9 center to center whereas chevy old school rods are 5.7 ctr. To ctr. I call it the baby Lt .1.
Great video,,,,good junk😊😊😊
nice stuff like these vids about the 90s SBC cant wait to see flow numbers for lt1 and lt4 heads the current gm fastburn is based off the 1996 lt4 head if you get a chance you should put those lt4 heads on the lt1 with 1.6 rockers and dyno it so we know what a stock lt4 does on the dyno but you will also need a lt4 intake to that b/c of the taller ports
you said your gonna do testing on the lt1 curious how are you gonna run it if you stay efi?
FINALLY! I GET MY WISH AND GONNA SEE AN AMC BUILD! Jesus christ hehe.....btw folks a 401 Amc would kill most big blocks when properly prepped/// esp if using BULLTEAR INTERNALS!
great job 😊
If your using a Holley all you need is crank sensor, tps and you can go COP.
Not sure about that block, but you can get 1pc seal to two pieces seal conversion adaptor to replace the one piece seal crank with two PC seal crankshaft
leaky injectors are a pita. i've ran into a ton of them even brand new. you'll notice it most on hot restarts.
I really have to ask, isn't it easier to notch the bore above the ring than fiddle with the valve? Everything I've read tells me these have 305 size valves, they have 1.84 intake valves and actually use the same intake valve, as in the same part number, as 305 pickups and vans from 1996-2002. The lt1 heads have 1.94 intake valves and should clear the bore no problem even if the chamber overlaps the deck. You would have to use a 5.7l head gasket for the bigger bore size
Short Stroke makes rev faster Smaller rotation assembly! I have a 74 Pontiac Super Duty 350 i would like to see you do testing on it needs a refresh befor testing!
I was thinking you might have to bevel the top of the bore, I would do that to the 4.250 BBC'S bore. Chevy did it to the 396s bore
"They fit fine, you just need to modify the firewall for clearance"
/s
Lot of parts/ stuff on the shelves. Do you inventory the parts available for testing. Or is that a daunting impossible task ? This is all great information for those willing to absorb it. Good video.
Do the 302 with ported lt4 heads, 11:1 compression and the old comp 280ar single pattern solid roller.
A friend and i did a 403 olds with 70 455 tornado heads
Richard, what do they do, after hours they let you aaaaaahhhh just run wild in there. Man you got it made.
8.1L with twin S480’s would be epic ( trying to keep the torque down with lag )
Would the lt1 heads bolt up with the spider injection
Your rocker arms effect more than lift numbers on the cam.. but im sure u knew that.
I cant guarantee this but i think the L99 is basically maxed at .060 over bore. You wouldnt get (relatively) close to a 4" bore.
305 Vortec block swap with the 4.3L crank, rods, & pistons with 5.7L Vortec heads
Good video sir
Thanks-just ran the LT1 intake with my home made dist hole
@@richardholdener1727 lol indeed sir that custom Distributor hole is a nice touch
They should fit... Isnt the 4.3 "baby" the exact same as far as external size, fixtures, and mounting points? I figured they used the same iron head used on 5.7 b bodys, which definitely is interchangable..
different heads
@@richardholdener1727 Thanks for doing the comparison, the geek in me is totally interested. I hadnt even considered the 4.3 might have different valve and runner sizes.. How different are the 4.3 vs 5.7 iron heads- Ive only dealt w/ aluminum and Im still using a GTP CNC"d factory head(both heads flowed around 280/212).
Cant wait to see the 305 vs 302..
Right on
Do a turbo charged Big Bang on the lt1
The iron lt1 head flows a touch more on the intake side than an aluminum lt1 head but the l99 heads are WAY smaller than the iron lt1 head
also the iron flow less on the exhaust than the alu lt1
@@Madmax.3 yes the aluminum lt head has the good d shaped exhaust port where are the iron does not
If you put seafoam straight through them and soak them for a couple of days it will break down any build up in them I know if you do this on a semi diesel it will work
Hey bud anyway you could do a lt1 iron headed engine from like the Impala SS etc Richard holdner
Did you set that injector flow tester to do the injectors one at a time? all the other ones I seen does all the injectors at once
we can adjust it
Great build!
Can I put LT1 heads and LT1 carberated intake on a GEN 1 small block?
Will they bolt on to a Gen 1 yes, but the water passages will not line up. You could theoretically make this work with a lot of welding and modifications but it wouldn’t be worth it when you could just run a vortec head which has the same ports as an LT1
I would like to build a small Small Block Chevy V8 to get as close to 35 MPG as possible and run as clean as a new car. Maybe even with twin turbo's.
There’s a guy on UA-cam that tuned a corvette to get 40 mpg highway by leaning out the Air fuel ratio at cruise...can be done but not on a carbureted engine...easy to do on an Ls based engine
Where does the big bang big block fit in you schedule?
I know it a weird request, but can you do some videos on the Miata 1.6?
I actually designed a number of intakes for the 1.6L and 1.8l Miatas
@@richardholdener1727 is there plenty of meat in the cylinder to be able to bore the block enough for the LT4 heads to fit. Then you wouldn't have to notch the cylinders. I'm sure that you probably want to keep the cubic inches or the cylinders as close to factory as you can. It's a serious question because I don't know if that L99 has the meat to be able to bore it. Thanks Richard for the videos
Hey Rick, I come from the Toyota crowd and have only ever worked with JZ and UZ V8 motors... Im looking to pull my first LS ((LY6)) and wondering if you could give a small rundown of tools that would be to pull the engine and trans combo. Someone said all my metric tools should be good... Can you give advice sir?
YES METRIC-YES 1/2 ELECTRIC IMPACT-SOME USE SAWS TO CUT FRONT END OFF
Balancer requires a puller/press.
LS are metric
the baby lt1 heads dont flow 200cfm on the intake and no there is a dramatic difference in flow between the lt1 and lt4 heads about 18-25% worth also you can gain more by port matching the lt4 intake to the taller lt4 head ports from the factory the lt4 intake blocks about a 1/4 -3/8th of a inch of the intake port
The L99 heads will flow more like 220 cfm. They have essentially the same port, valve and valve job as a L30 305 Vortec. Would not be suprised at all if they outflow the aluminum LT1 heads.
do you have flow numbers from L99 heads?
Richard, I wish I had numbers for a stock set but I do know a set with some port cleanup and a good performance valve job ended up around 235 cfm with a 1.84 valve. I would assume the cleanup and valve job were probably only worth 10-15 cfm. So that puts them around 220 stock and definately over 200..
@@chrisreynolds6520 no they are not they didnt even break 200 at 500 lift noone is running 600 lift on a l99 his newest vid even prove this
Can’t wait to see
What is the water line called that goes from head to head and to the intake?
Using a stock head gasket would answer the question and give you better visibility.
gaskets are often not bore size
@@richardholdener1727 True, they allow for an overbore, but the centering would be more accurate than placing a cylinder randomly on the head. BTW, this is a suggestion and not a criticism.
how about a 4 inch bore 3 inch stroke 307 build
Hi Richard, were the valve covers modified for lateral clearance of the stiffeners between the rockers?
we cut the supports-that's it
Thanks for your videos. I need to know what’s the max cfm u can get with LT1/4-5 aluminum heads. I have a stock LT1 in my 95 C4 and would like a few hundred more HP over stock as I’m not really looking to push the stock block or trans past 600 HP so nothing blows/ locks up. I’m using as a daily driver and not really looking to draw attention to my car anymore than already does so I don’t get pulled over just so they can make sum up (SMALL TOWN) grumps with nothing better to do.
near 300 cfm
Get one of jim halls lt1 mini rams they have a distributor hole
Richard, any access to a Series III 3.8?
They have the sinter forged rods in them.
I have not seen any in the yards-only series 2
@@richardholdener1727 cryo and nitride factory iron rods. Then see how they hold up throw on some different ARP hardware.
Problem with those series II are the head gaskets. Once you get up around 600 horse pressure
:/
So would 1.6 roller rockers help my stock iron headed LT1? I know I'd love to have a pair of those LT4 heads and intake. My 96 Roadmaster needs all the power I can throw at it.
yes they will help. how much they help will depend on other supporting mods. headers cam intake. on a BONE stock engine you probably wont get quite the 10-11 hp he did. but the gains will be there and get better as you do more changes. exaust-headers-and do on.
Not by much just get a turbo
@@ohshitwatsmyname no- to much compression. just not a happy combo.
1.6 self aligning rockers and ls conical valve springs.
Is th that going to be angle milling the heads?? Or just going to be flat?
this is ok..but i really wanna see the other other guys stuff..like y block stuff..or even some M,E,L, motor stuff ,,and some F,E stuff to
@DropDstar yeah..any M,E,L of any size would be cool..i think this small block chevy stuff is covered everywere on the planet 10,000 times over ..some oddball stuff would be good
You can convert any small block chevy head to work on a lt1 and use any sbc intake.
Pics or it’s not true
@@ohshitwatsmyname I'm not sure how to post a picture on here. I've got a set of ported 235cc rhs heads converted and will be using a rhs single plan intake. Dart will convert most of there aluminum heads also. When the aftermarket block 4.125 bore is finally released id say more will start.
What does “converting” let’s say a set of stock 305 heads required
@@ohshitwatsmyname if you Google how to convert sbc heads to lt1 you get a bunch of information. But basically you weld up some oil and water ports and machine some new ones. Most shops charge around $500 to do it.
@@ohshitwatsmyname i wouldn't convert a set of 305 head for a lt1 in the first place. You would only want to convert a aftermarket head the lt1 head out perform all stock casting heads out side of the lt4
The way I see any gain is with a taller crank more volume
I have a 1994 Z28 with the 5.7 LT1 will a gen3 tpi work with it so I can run a rear distributor instead of the optispark
the TPI lower intake won't bolt to your LT1 heads without a change in the bolt pattern
The LT4 heads had to have valve cuts in pistons hogged out so valve wouldnt hit.
cause its higher compression than LT1
Would using L99 head gaskets give you a good enough idea of the valve to cylinder clearance?
it would be another point of reference-I just need to yank a head
This is the method I always used when checking valve clearance on 283 motors with 327 fuelie heads on them. The head gaskets are cheaper to check with (timewise) and were cheap, and were eventually used after the race teardown. Used parts swapping was the name of the game back then, because we were always broke. We also saved old head gaskets as tools for checking as well.
@@richardholdener1727 forget yanking a head. buy the head gaskets only. , f Check with them. Return them if you like, but you will use them later in the swap anyways. A stitch in time, and all that.
Funny, been a subscriber for awhile, bought a 94’ Caprice with this same engine (never heard of it). What’s the chances?!
It was meant to be
@@richardholdener1727 I guess so!!
When will the camshafts be ready for sale?
Just un-shroud the bore a bit. I know you want big heads, cam and boost. It's a junkyard motor go nuts, can always get another
A you should compound that 293 straight 6
won't need compound
Wish I could afford to help out your testing, someone on my local fb marketplace has a Cadillac tunnel ram with two Carter’s but they want $900
What about the enginequest vortec hybrid ch350ga heads with that tunedport intake?
IMHO, I don't want u to get burnt out dude
I'm good
Thanks for the vid
Maby try a good valve job on the factory heads .
Do a LC3 and a L37 please!
On our 3.625 bore and 3.0625 storke 253 Holdens with the 304/308 1.94/1.60 valves designed for a 4.000 bore....we relieved tge bore with a dremel in the area from the deck to 70 thou below. Ring lands on 1.563 compression height Chevs park 165 thou before the 9 inch deck ends. You can do it
I just want to know if, I can use these heads on a small journal 327? 😎
these are reverse flow
I heard if you weld the water passages closed you can use them on a 350
Wanted to see 6.2l with 706 also couldn’t find much on lq9 or 4 with 706s without cam upgrade
that's not a good choice
@@richardholdener1727 why wouldn’t that be a good choice?