Need some help with flow on these heads. Can the 86 iron heads be ported enough to get them to flow like the 87 alum heads? I don't want to step up to the 113 heads because I don't want to have to buy new headers to fit the D exhaust ports.
I guess what I am needing is some advise on is it worth buying a set of 87 alum heads for the performance upgrade or can I work over the ports on the iron heads and get the same results.
The car is used strictly for autocross so I am wanting to get the most bang for my buck.

There's very little meat in the early 86 iron heads for porting.

I put my grinder to the early 86 Vette iron heads a few years back and it didn't take very much before I had a nice little hole in one of the port walls. The vertical wall(s) are REALLY thin.

Jake

Cant do much with those heads unfortunately by the time you freshened them up meaning valve job surface seals springs etc and some bowl work at least youre well on your way to a budget performance head like an edelbrock or :gasp: some patriots, vortec etc.

EQ heads make a decent iron vortec head thats pretty reasonable check into it.

Unless youre in love with the 113s dont bother sinking money into them either without big valves and butchering the ports you wont get them to flow for beans on the intake side anyway. 220-230 if youre lucky on stock valves. Exhaust different story

The 128s that came on 87s were great for fuel mileage but not so great for flow. They will get you some cheap compression but if you can, seek something better.

I put my grinder to the early 86 Vette iron heads a few years back and it didn't take very much before I had a nice little hole in one of the port walls. The vertical wall(s) are REALLY thin.

Jake[/QUOTE]

I agree there isn't much meat in the walls. Looks like all that would be possiblr is to do some gasket matching on the intake side.

I have to stay with a head that is a factory L98 head or move into a modified class which I am not wanting to do.

are the combustion chambers smaller on the 128 alum heads that would raise the compression or are the piston domes different on 87?

128s have 58 cc chambers.

I put 113 heads off a 90 on my 86 and used the same Hedman Headers with no problems. The 113s aren't great heads, but they are better than than the cast iron ones and take 40 lbs off the front of your car.

Those heads are [ supposedly ] the same heads that you find on the ZZ4 crate motor?

So I guess I have to ask for a definition of Great? If you mean $3,000 custom heads , I got ya.


TJM

[QUOTE=Paul Ruggeri;1575320730]I put 113 heads off a 90 on my 86 and used the same Hedman Headers with no problems.

Since the floor of the exhaust ports was raised approx. .100 , wouldn't there be a problem with the flange sealing on the top of the port?

TJM, I was thinking compared to AFRs, which will make more power and are around $1500.
IBVETN2, all I can say is mine don't leak and I've had them on for years. Even when I put the stock manifolds back on to get it smogged, they don't leak.

Today I started swapping my "off-road" exhaust, headers and duals, for the stock exhaust to get my smog check. Anyway, the exhaust ports are normal SBC, not D shaped. Perhaps the OP is thinking of LT1 heads.

I am not sure what LT1 exhaust ports look like, but I would think if yours do not look like an upside down D they are not 113's

So are 86 and 87 pistons the same? If iron heads have 76cc chambers and 128's have 58cc chambers wouldn't the 87 pistons be dished since the compression ratios are listed as the same

87 pistons are dished. I have never seen 86 pistons. You know late 86s had 128 heads too right ? Be sure you are looking at the correct specs.

Yep. If late 86 and all 86 verts had 128 heads then wouldn't there have to be 2 different 86 pistons to keep the compression ratios the same between all of them?\

If that is the case then what compression ratio would you end up with if you used 86 iron head pistons with 128 heads?

I think they used the same pistons. The info I have says iron head cars had 9:1 and aluminum head cars had 9.5:1.

Can you port the 113's? Cuisinartvette could bring some 113's to life.

They only flow around 200cfm stock. But there really are alot better choices for heads out there. I guess if you stuck with those castings make the most of them.