Vinscully50

I've going to a pick and pull scrapyard next week, I'm mostly looking for a few interior components. Anyway, over the phone the guy said they have a few Corvette C4s in the yard. He's not sure what motors are in them exactly. If they are the L98 years and they still have cylinder heads would that be a good mod? Could I pull the C4 heads and use them on the LB9? I recall reading at one point that the Corvette and the F-Bodies used a slight different Intake Manifold base, I'm assuming I need to pull that too?

Or I am saving up money to build a mild 350 and hopefully swap it next year. Would Corvette heads make a great budget TPI 350? I'm planning on buying a Chevy Performance Short Block and going from there. I still want the car to be streetable just a little more powerful. My plan would be to find them, pull them and have them machined/rebuilt.

Drew

iTrader: (58)

Ehhh... Not really worth messing with. The 87-whatever L98 used aluminum heads with centerbolt valve covers and the 86-earlier intake bolt pattern (angles really). But they're really not worth the trouble. If a Corvette is in a junkyard and if they'll let you take just the heads, are they really something you're just going to bolt on without rebuilding? Would it really save that much time and money vs taking the entire 350?

You could use aluminum L98 heads on a 305, but why? It's not like the heads are the weak spot in the 305 package. By modern standards L98 aluminum heads aren't anything special. Virtually any commercially available head currently sold is going to be as good or better. If anything take the entire Corvette engine, but not if they're going to charge you the 'Vette tax'.

Vinscully50

If I did find them I would have the heads machined and rebuilt. My plan for a 350 build, would be a mild cam, mild heads, bigger throttle body and porting the plenum and runners. A close friend of mine is a machinist so I would ask him to help me with this.

My other options for heads are to rebuild the stock 305 ones or Trickflow aluminum heads. Exhaust was done close to 3 years ago. I have a full Hooker set up on the car (Headers, Y-Pipe and Muffler).

I want to plan out everything a year in advance to know what I am getting into.

John in RI

iTrader: (167)

WTF happed to this place ????


Some things are just "worth it". There's no way you could ever get aftermarket Aluminum heads for what the junkyard will charge. ( Got mine @ at the local bone yard; L98 heads off an 80K original mile car. ) Could have bought more heads that day than I could carry-out for the price of a SINGLE aftermarket aluminum head. Not everyone builds a car to be a 600HP rocket-ship or has a thousand $$ to throw at aftermarket heads. Corvette heads for a budget build,....... absolutely !! It's not going to get you the most HP compared to every other head out there,....... but it sure adds a bit of "COOL FACTOR" to a budget build. Not as good as Iron when it comes to cooling efficiency, but their much lighter and easier to port than iron,... + they never rust.

Vinscully50: If you do pull used heads BE SURE to take the hardware too. IIRC the factory head bolts were different for the Vette Aluminum heads compared to bolts used on Iron-head engines.

Vinscully50

If I find them, I might take the entire TPI base manifold too since I heard it's different from ours. I'm not building a 600 hp monster, I'm happy with 300hp. I already have had the 700R4 fully rebuilt with mild upgrades and full Hooker exhaust. The engine is the last major step.

mikeceli

iTrader: (2)

So OP has a 305 LB9 TPI engine, like my 89 IROC Z Vert? Won't 350 heads be larger combustion chamber, than 305's? Causing lower compression. I too would like to put some better heads on my 305(MUST be ca SMOG able)

John in RI

iTrader: (167)

Mike; This question is why I responded. I've never installed 305 heads on a 350 or 350 heads on a 305 so I'll be NO help - at all - when it comes to your question. I'm sure there are more than a few other members with the knowledge & willingness that will be glad to HELP you out.

mikeceli

iTrader: (2)

Just going by memory, off the top of my head, 305 heads have 58 CC and 350 heads have 67 CC combustion chambers. I recently telephoned GM Performance and was told they have no parts for the 305.

LiquidBlue

as far as i am aware, can’t put 350 heads on 305 w/o milling, etc. and iir, corvette heads do require different manifold. some after markets will work as welll. i.e. edelbrock/acel

Drew

iTrader: (58)

Hold up a second there... I didn't say 'aftermarket aluminum heads', I said any commercial available head. This far out, the chance of finding a pair of heads from an 80's car in a junkyard that you can just bolt on and go, is pretty slim. You're probably going to have to put money into rebuilding the heads. You'll spend enough acquiring and rebuilding a set of junkyard heads that you can probably find a set of new heads for the same or less money.

There's not much benefit to an aluminum head, weight, cooling, and? It's not going to make a 305 go faster just by bolting on L98 Corvette heads.

Don't waste your time taking the Corvette intake unless you understand WHY it's different. Corvette heads use the bolt angle used in 86. If you've got an 86 like what's listed in the OP's profile, the stock intake will bolt right up to Corvette heads. Aside from the bolt angles, the only difference between a Corvette and Fbody tpi manifold is the EGR is different. Using the Corvette intake would let a person plumb the EGR source into the exhaust, but it'd be easier to just delete the EGR, or just don't waste the time changing the heads to save some weight.

Corvette aluminum heads have smaller chambers than iron 350 heads. So that's not really an issue.

What's happened around here is that people come up with ideas like "Corvette heads must be better than what I've got" and people are unwilling to look into what is actually different about them. There's a lack of understanding, and a refusal to research the topic beyond asking for help. Going out of a person's way to get junkyard Corvette L98 heads for a "mild" small block build, hasn't been popular in decades. There are better choices. There's a reason you don't see people doing it, it's a waste of effort.

John in RI

iTrader: (167)

Lets see: a budget build 350,.......

lets start with a bare block and a pair of $120 heads from most boneyards with a decent donor vehicle: ( Aluminum head, Iron head, Vortec, MPFI; what-ever cause' it don't matter.) If you hit the yard on '1/2 off day' or "all you can carry day" than you can pay even less. (cheapest set of Vette L98 Heads on E-Bay right now is $500)

http://www.henrysautoparts.com/forms/ppp.pdf ( might buy a set of LT1 heads from this place in a couple weeks - waiting for the car to 'drop' into the yard. )

OR:

Lets start scrolling the SBC heads on Jegs,..... cheapest of SCB heads set starts @ almost $700,... ( no rockers, no hardware, etc.. ) & the next "CHEAPEST" pair of heads is over a $1000.

https://www.jegs.com/webapp/wcs/stor...0002&langId=-1


Ya' dude,..... I'm pretty sure that the $800 saved over the cost of new heads is worth it to some members. Just because it ain't worth it TO YOU doesn't mean the same is true for everyone. Buying a new set of (ANY) aftermarket heads isn't somthin' everyone can afford and helping other members build on a budget used to be what this place was ALL ABOUT. I saw a recent thread where a member stuffed a TPI into a 4th gen,...... probably a "waste of effort" to you but - obviously - worth it to him. Do Ya' get it ?!?!? ( Or are you gonna' post how much of a "waste of effort" his project is when you see the thread ? )

Drew

iTrader: (58)

Anything anyone posts here is their opinion, so what does it matter if I share my opinion and you disagree with it? OP asked if they'd be a good mod, I gave my opinion. You don't have to take it personally that I wouldn't bother.

You can jump on car-part.com and search for aluminum L98 heads, the results for all the junkyards in the system don't fill a single page of results. Average cost of a single head is about $200, and the message conveyed by the results is that they aren't terribly common, and the vast majority of salvage yards probably aren't interested in separating heads from a good engine they could sell whole. Maybe C4 Corvettes are piled three deep in the junkyards where you live, around here they're not something you find in the pick n pull yards. And whenever I suggest a person look for anything in a junkyard, people act like pickens are even more slim elsewhere...

So assuming you find a C4 Corvette in the junkyard, and assuming the yard will even let you take just the heads, pretty safe bet they're not going to be $200 or $250 for the pair. $500/pr is probably more realistic. That C4 probably isn't going to be a low mileage trailer queen either. So then you take those heads to the machine shop, have them disassembled, cleaned, inspected for cracks and damage. Say at the minimum you want a valve job, maybe you want the surfaces milled... How long do you suppose the almost $350 you saved (vs a brand new assembled, ready to run, pair of Vortec heads) is going to last when you start paying for machine work and labor?

And what exactly are the benefits of Corvette heads that make them worth the trouble? A person can read a lot about them from a quick Google search. The general consensus is that they're just not a great performance head. But don't take my word for it...

Orr89RocZ

iTrader: (20)

Corvette L98’s should be near 58 cc as well. So for a 305 they aint bad.

big advantage is they are aluminum which saves 40 lbs or so, and you could get away with higher compression since they cool abit easier/quicker

if you planned on porting them, aluminum is easier to port lol so its nicer to work with but you need to know what you are doing. You can get 240-250 cfm out of them which will support alot of power.

Everyone makes a big deal on the bolt holesfor intake...its not an issue just oval out the center holes, its easy to do
only issue is if you need egr, the corvettes did it differently so keeping the vette manifold egr stuff might help you

keep in mind the heads should be rebuilt. If you get them for 300 a pair, you are doing good but a machine shop head rebuild will be 300-500$. So now you have 700- 800 into them.. more than halfway there to a better head if you had a 350. For a 305 i wouldnt bother with aftermarket stuff unless dead set on being different. Trickflow makes a 305 head

sofakingdom

iTrader: (1)

As Orr says, the 113 heads are around 58cc, about the same as 305 heads.

Problem is, they're ALUMINUM; which means, the compression is REQUIRED to be about ¾ to 1 full point HIGHER than cast iron, to attain equivalent performance, because of the difference in the heat conductivity of the 2 materials. Aluminum simply allows more of the energy in the fuel to "leak" out of the cylinder, reducing the amount available to push the car around, if all else is equal.

I don't think they are a good "upgrade" choice for an otherwise stock 305 AT ALL. But that isn't where the question started out, anyway.

On a 350, what you initially asked about, they are closely equivalent in performance to the 083 that came on the F-body L98. Again, not really an upgrade, if you were starting out with one of those. However, for a basic stock-ish build starting out with nothing, they're about as good as anything else STOCK that you can bolt TPI to, given the generally disappointing results people get with the Vortec TPI base. As Orr says, they can flow pretty good with a GOOD port job, but that pretty much shoots "budget"... reason being, YOU won't be able to attain those kinds of numbers until about the 50th pair you scrap while testing various treatments on your flow bench, and by the time you PAY somebody that already DOES KNOW how to get it done to do it for you, you're into aftermarket head territory in terms of $$$$. And then you're gonna be stuck with TPI ANYWAY which limits "performance" so severely that none of that will make any difference ANYWAY.

If you get those heads, get the intake that goes with them as well, if you are in California. You'll have to get THE WHOLE Vette EGR setup and plumb it on there, which once you see it, I think you'll agree isn't very swap-friendly. Possible, just not friendly.

I would NOT, under ANY CIRCUMSTANCES WHATSOEVER, recommend "rebuilding" a 305, particularly not if "more performance" is part of the goal. For what little more a 350 would cost, you get so much more that it defies logic how anybody would stick with the small bore. Kinda like, if you could walk into the grocery store with $10 and pick up one package of T-bone steak and get 8 oz, and sitting RIGHT NEXT TO IT is a package of THE EXACT SAME steak except 12 oz for THE EXACT SAME PRICE, what kind of IDIOT would pick up the 8 oz one? It's no different choosing between the 2 engine sizes. For the same reason, I would NOT recommend buying ANYTHING 305-specific, such as those Trick Flow heads. Not because they're not "good"; rather, because when you realize what a EFFFFF-UP building a 305 was/is in the first place, you're stuck with something that isn't appropriate to a better choice, meaning you throw the 305 stuff in the trash and RE-BUY something else. Again, not commonsensical. Leave stuff like that for people who are racing in classes that REQUIRE a 305 but allow aftermarket heads. For that, they are PERFECT. For anybody that has the option of installing a "bore kit" into their 305 instead, they are a mistake.

Whether those 113 heads would be appropriate to a "Chevy Performance Short Block" depends ENTIRELY on what short block it REALLY is. If it comes with flat-top pistons and low deck clearance numbers, they'd be a good choice. If the short block you choose is the phone company van replacement model (the cheeeeeep one), not so much.

CKone

iTrader: (2)

Correct me if I’m wrong but wasn’t the Corvette L98 9.5:1 with the aluminum heads? Taking into account the 1 point higher for aluminum heads, shouldn’t this have been higher? This always baffled me a bit

CKone

iTrader: (2)

And to back up what others have mentioned, I bought a complete L98 strictly for the heads to put on my 91 LB9 Formula for the weight reduction, but since I had the 350 they came off of........

Orr89RocZ

iTrader: (20)

most were around 9.5 to 1. The 90-91 stuff had flat top piston which would have made it closer to 10.2 to 1. Gm did change pistons in late 89 into 90.

LiquidBlue

always learning something over here on this board. was taken back by aluminum heads reducing compression/losing power. don't really understand it. the only thing that makes sense is heat transfer is different, but don't understand how that could change compression or power.

ran across this article

https://www.hotrod.com/articles/ccrp...er-heads-test/

LiquidBlue

This guy shaved 0.8 sec off his 1/4 by installing corvette heads on his 305 https://www.thirdgen.org/forums/tpi/...tml#post264228

Drew

iTrader: (58)

Don't assume the rest of his combo was stock. Willie had reasons to do what he did. You're also talking about twenty years ago, when options were considerably different than what options are possible now. There's quite a bit of missing context.

Orr89RocZ

iTrader: (20)

.8 heads cam i could see with supporting mods

LiquidBlue

according to his post, it would appear he changed the cam. For someone like myself, historical preservation is a top priority when maintaining the car, or adding power to it, not necessarily maximum power that would be available in 2020. Back in the day, one would have Corvette heads available to them, so its a viable option to preserve history.

89Warbird

Here are some 305 heads. Not sure how they are upgraded from stock. You need to talk to the folks at SDPC to see if this is what you want.
https://sdparts.com/i-24079249-atk-2...model%3DCAMARO

IF you want L98 heads get the iron heads off of an F- body.

mikeceli

iTrader: (2)

Summit sells Verge reman heads, $179.00 ea IIRC.

http://www.qualitycylinderheads.net/services.html

LiquidBlue

I ran across some flow numbers on the Corvette L98 heads somewhere. really not that great. I guess the advantage to them is historical value, lighter, and if ported, could probably flow good, and maybe easier to port

Orr89RocZ

iTrader: (20)

Yup. Save 40-50 lbs goes along way