ejscarfo

I'm in the process of a rebuilding an engine to drop into my 85, a retro-roller actually.

Everything I've read about the stock iron heads seems to limit what can be done. I was planning on rebuilding the heads, but now I'm leaning to something with better breathing. I have a line on the aluminum C4 heads, casting 14101128, and was wondering if they flow better than the iron heads. Would it be an improvement or about the same?

rklessdriver

There is alot more to it than just flow.

The 128's are about 40lbs lighter.

The combustion chamber is 58cc which will give you some added compression.

Just on those 2 things alone I'd tell you to get them if the price is reasonable.

The stock 128 castings I flowed were about 200CFM@.500 lift with a fresh 3 angle valve job. This was in the 1990's.

They can be improved easily with proper bowl sizing (start with 90% of the valve size) and a 30* back cut on the intake valve will bring the low lift numbers up by about 5-10CFM without hurting anything.

Will

John A. Marker

with rklessdriver.

First off.....just realize that the 85 cast iron heads suck. They were good at the time, but by today's standards....yea....they suck. If you can get the 128's at a reasonable price, then go that direction. Or look into aftermarket heads.

Right now the 85 has three pinch points. !) is air going into the heads, 2) are the heads themselves and 3) air getting out....exhaust system. Addressing one thing or two of these points will make an improvemetn, but you are still left with another third constriction within the system. Address and three and you will see a good improvement.

Consider adding roller rockers to the new heads. Small HP increase and cooler oil temp levels. The 85 with stock cam runs better with a split ratio of 1.5 on the intake and 1.6 on the exhaust than if you went to all 1.6's.

mtwoolford

sometime around the early (?) mid eighties, the factory changed the angle of the center two intake manifold hold down bolts; just make sure your intake / plenum will bolt up to the later style head

84wannabezo6

corvettes don't use angled bolt holes in the head

vetteoz

Vettes kept the old style bolt angle when they went to alum heads
Only the cast iron heads ('87+ ? ) got the revised bolt angle on the 4 center bolts

In any case ,it is just a matter of elongating the 4 holes to make one style intake fit on the other;
just like the aftermarket do with their intakes

mcm95403

I looked at this when I was getting into rebuilding mine last year. Considering the machine shop costs here in Kalifornia it was cheaper to buy a set of GM Fast Burn heads for $1000 than it was to rebuild my 113's.

Choose carefully and do your research.

ejscarfo

Well I missed out on the 128's, someone got to them before me. Found a set of rebuilt 113's which I'm told are better. The stock 85's intake, which I'm having ported, will bolt up, correct?

Also, I plan on making this 355 a retro-roller and Summit showed me a good kit to make that happen. It didn't include roller rockers though. Anyone have any suggestions for a roller rocker to go with the 113 heads?

rklessdriver

Your 85 intake will bolt right up to the 113 heads.

I'd recommend Scorpion rockers. Be sure you buy the small body self aligning model for use on the 113 heads.
Will

ejscarfo

I also got a line on a set of Camaro Z28 LT1 aluminum heads. Will these work as well?

cv67

Nope not without a ton of work and its not worth it.
If you can find one good 128 head I have one Ill give you just cover shipping.

ejscarfo

I'm on the lookout...will let you know.

LoneStarV

113's are abundant and you should be able to pick up a set cheap. Agree on the Scorpion rockers....summit has them.