I JUST picked up a 1988 IROC 5.7 Automatic.
This will be a long term California play toy with emphasis on backroad/canyon carving with street&strip racing secondary.

I've spend most of today just reading posts and have developed some questions. I was hoping to come across a post that cronologically covers the potential Head upgrades starting with an explaination of the good the bad and the ugly of the stock system.

Second: how would a set of amumnium heads benifit from a wrecked 5.7 Corvette engine or even a set of used ZZ4 58cc? Heads. Other than engine weight savings, is there any other benifits of an alumnium head.

Apparently many folks felt that the Edelbrock heads were only worthwhile if they were used and *CHEAPLY* priced.

Another group didn't feel it was worthwile to mix and match off the LT1 Heads

Most posts were very serious about a 'trickflow' head set?

Lastly: can a basic back yard mechanic like myself improve on a set of factory heads using a book and a dremel???
Thank-You for any response. I'm in no hurry, but do want to be ready to know a great deal when it comes up. Nitro

 

You will probably get alot of opinions here. But if you are looking to go with some sort of budget I say you can't beat Vortec heads on these motors. Especially a street car. And they are CHEAP too. Even new they are cheap.

lata
CHRIS

 

As cast iron heads go, the stock iron L98 heads aren't that bad. GM used the same castings on crate motors rated @ 300hp. Keep in mind the 330hp crate engine uses the Vortec heads. So 30hp less than Vortecs that everyone sings the praises of. Since any head newer than about 1970 is going to be a smog head the stock iron L98 heads are about the best choice if you want something that's actually going to bolt in place and develop decent power. The aftermarket options for a direct replacement head are fairly slim, the Vortecs require a special intake and you have to dance around the EGR issue.

As for upgrading the stock heads, why bother? By the time you invest the money in larger valves, machine work to make them fit, machine work to make the mounting surface smooth, porting, etc you'll have as much invested as you'd have in a new pair of heads.

The options are pretty limited really, there are the Edelbrocks or AFR's if you want something thats reletively bolt on and go, Vortecs and others if you want to do some work.

 

Why then, have some folks on this board switched the stock head out with the alumnium corvette heads? Other than weight savings is there any advantage what-so-ever???

I'm just trying to figure out my long-term plan with this puppy, so I can keep my eye out for the bargains as they come along..... Nitro

 

The "vette"head or 113 castings are the same as ZZ4 heads only the ZZ4 heads have the lightweight fastburn valves in them .

People like them because they up the C/R a bit 64cc vs . 58 cc.

They port out pretty good ( according the the lingenfelter version)

But they to have an EGR issue you have to get around . Ther vette puts the EGR back by the disributor. Instead of under the plenum like the L-98.

Hope some of this helps a bit

 

you don't need larger valves for more power. Unless you're going to get MANY other mods, the stock 1.94/1.5 valves are fine(GM has made over 350hp w/ 1.94/1.5s). As for hp, as stated, GM made 300 hp w/ these heads "untouched". GM doesn't port heads. If you pull the heads and tear them down, you'll see a big ledge under the valve seat, smooth this into the "bowl". Then take a set of intake gaskets and set them on the heads and scribe the hole onto the head. Now grind on the port to match the gasket. Don't get to carried away here, just roll the edge over and tapper it into the port a bit. Grind in the tp of the exhaust ports and give them a nice arc towards the port. You'll be happy you did. I'd then reccommend finding a reputable machine shop and have them do a good valve job. - note: you can buy upgraded valves, springs, retainers, locks, and seals for around $140 from Competition Products. - If you're gonna pull the heads, put in a decent cam and port the intake while you're there. - as I said before, you'll be happy you did....

 

I totally agree with Shagwell because he helped me build my engine and did all the tune work and all i have is an 355 L98 heads with a full competition valve job with a 503/508 with comp cams 1.52 roller rockers Stealth Ram running stock injectors and stock computer shorty headers flowmaster exhaust and built 700R4 with 2200 stall converter and i run 13.7 @101 pulling a 2.1 60ft but my best was a 1.9 with LTR

 

Thanks for this input. It is EXACTLY the information that I was hoping to hear/learn.

For myself, it has become long apparent that it takes a minimum of 300hp and a strong torque curve to have the power on tap to do the occasional powerslides and for steering out of the corners where I have stupidly misguaged the exit apex'.

I just sold my Lexus SC400 to get this Camaro as I was spending a fortune upgrading & balancing the SC's performance and finally realized that the Lexus V8 engine's factory horsepower will always be limited to just over 200 horsepower. They are such a sweet ride out of the box though, sigh.

Again, many thanks for y'all taking the time to answer my questions. Nitro

 

you should have ALOT more left in that combo. i'm doing 100mph traps with 2800stall headers and exhaust on stock TPI/chip/cam/heads

with a strong L98, some bolt ons will give near or exactly 300hp on motor. my 100mph traps would signal at least 275hp on crank. with the auto, i'd say more like 280ish. after market TPI stuff and maybe 1.6 rockers/AFPR and your looking at 300hp easy