I'd like to eventually put a set of aluminum heads on my '89 L03. From reading some of the TGO threads, it appears a set of L98 113 aluminum heads will work and be a good price/performance option.

I'm wondering:

1. What will it take to get them to work properly (machining, tuning, etc.)?
2. Will stock parts work (rockers, pushrods, gaskets, manifold, etc.)? Which ones, L03 or L98?
3. Are there differences in years I need to be aware of (chamber size, valve covers, manifold, EGR, etc.)?
4. Are there other aluminum heads to consider for the money?
5. What will the resulting compression ratio be?
6. Any reasons not to go to an aluminum head?

I'm planning on installing a set of 2460 Hooker headers, an LT1 cam, and a 3.23 posi rearend this spring/summer - how do these upgrades enter into the decision?

Appreciate any information offered.
Thanks.

 

i think you would be better off with 305 TPI heads then the 350..u might lose abit compression

 

the 113 heads have the same combustion chamber size as 305 heads, so your compression stays the same.

EGR wont work, they used some weird external EGR or something. It just doesent work.

The center bolts on the intake manifold will have to be drilled out a little bit to get the holes to line up, easily done by yourself with a drill.

Stock parts will work, but whatd be the point in getting new heads then? Definitely upgrade to stiffer springs and better rockers, if the car has higher miles get new pushrods and lifters too. Stock gaskets work fine.

 

Red:
- I didn't know 305 TPI heads were aluminum.

Tim:
- Good to know the combustion chambers are the same size.
- Didn't know that about the EGR. Is that true even for later model ('90+) heads?
- I thought the TBI manifold would bolt right up w/o having to drill the bolt holes. Does that depend on what year engine the 113's are off of too? I'm also considering going to a better flowing carb manifold and using an adapter to mount the TBI.
- Other than the mainfold, the stock parts I was wondering about were specifically the rockers and push rods. The rockers because sometimes the heads are sold w/o them and could I use the one off the L03. Was wondering if the studs were the same? I figured the stock 113 springs will be an upgrade to the L03. I'll be replacing the lifters when installing the LT1 cam. The push rods b/c I was wondering if the L98 & L03 were the same length. They certainly could be replaced while installing the cam.

Thanks for the info.

 

Far as I know the thing with the EGR and intake manifold is the same for all year 113 heads.

Id really upgrade the rocker arms to some 1.6 roller rockers. The stock ones, really suck.

I used stock pushrods and lifters without any problems.

 

do you happen to know if the iron L98 heads from the F-body (64cc chamber) have another casting number than the 58cc alum L98 heads from the vette?
i remember a section about the odds of these aluminium heads in "John Lingenfelter on modifying SB Chevys". i'll look it up later and post any additional info i find.

#1:

 

okay here is the rest:






hope we can put that to some use
i recall timothayyy is using these heads, maybe he can tell us something about the mods he did to them before they bolt up to our L03s. i also recall there is an accessory bolt hole you need to add (not mentioned in the article).
anyone know if you can actually add egr ports to a head?

EDIT: i just noticed that Tim already chimed in earlier in this thread lol.. still early in the morning over here. you guys have a nice sunday

 

The valve covers can be the standard run-of-the-mill center bolt style. The stock L03 ones will fit. The rocker studs are standard 3/8" units (7/16" into the head). As noted in the article the guide plates are soft. So need to either replace then with hardened plates or use self-aligning rockers.

Note that step-up guide plates will interfere with the bracing inside of the valve cover. This bracing can be removed for clearance or flat guide plates can be used. With guide plates no need for self-aligning rockers. But be sure to get hardened pushrods to go with the hardened guide plates.

If you get a set of roller rockers such as pro-comp's that require a longer rocker stud, then step up to 7/16" studs and the rockers to fit. Doesn't cost any more and the valve train will be more stable.

The head bolts are slightly longer then the bolts used with CI heads. And they require a hardened washer under the head. IIRC the added length of the bolt is to make up for the thickness of the washer. The GM bolts are pricey so a set from ARP may be the better way to go.

Standard pushrods can be used (flat tappet or roller). Although valve train geometry should always be checked and the pushrod length adjusted to suit.

The intake manifold bolt holes are all at the same angle, the older style SBC intake pattern.

For EGR, the crossover has a cast in plate to mate to the intake. This seals the crossover in the intake manifold. There is open air between this plate and the exhaust ports. So can't just drill a hole for EGR gases or a heat riser. The hole would open up into the lifter valley.

Scoggin-Dicky (did I spell that right?) I believe makes an EGR kit for use with these heads. It taps into the exhaust and provides a place for an EGR valve. Just need someplace to dump it into the intake.

For too high of a compression ratio, I wouldn't worry about it being 10.5:1. Use a decent head gasket (no 1010's) with a thickness in the area of .038". The stock GM gasket for these heads is compressed at .052". This is on a 350.

Although this does depend upon which piston is used. I would definitely spend some time with one of the many compression ratios calculators found on-line.

And don't forget to use the flat gasket seat 3/4" reach spark plugs. Autolite 3926 is the stock Corvette plug. With the 3924 being a couple of heat ranges colder for modified engines.

RBob.

 

Rbob nailed it

 

hate to bring up an old thread but it has some good, relevant information that id like to reference.

Rbob, that was a great post. it answered a lot of questions i had about these heads but i do have one more. im going to be using these heads with a holley tbi intake. what would need to be done if i wanted do eleminate egr all together? since the 113's dont have the egr crossover, i would assume you would only need to address the intake correct?

anyone else thats running these heads or intake, id really like to hear your experiences as well.

 

EGR block off plate is all you need and remove EGR from the ECU (otherwise youll have a check engine light)

OR just get a TBI to carb adapter plate and run a carb intake that doesent have EGR on it.