tmichaud

You could be right - I can't seem to find the original spot where I read about this.

What was interesting was that these "mystery" heads were ordered from GM performance parts, and seemed to be CNC machined. The person had them flowed and had the fantastic numbers...

thirdtimevetteowner

ZLX,
Thanks for the comprehensive flow chart. It has about every head on the planet!!



rk

yimmys85

Hey guys just found this thread. I went to get plugs for my '91 Vette with the last year of the L98 and they asked what heads it has. How do I know for sure if it has aluminum or steel heads?

Thanks.

the blur

Aluminum heads, unless an F body guy stole them.

topfuel67

If your engine/heads are original they're aluminum. Cast Iron were phased out in 86. If you really want to be sure put a magnet on them.

the blur

I'm not sure, but some heads are straight plug, and some are angle plugs. I don't remember which are which.

THE 383 admiral

From this currently hypothetical upgrade.
The F body has Iron heads.
The Y body recieved aluminum upgraded heads.
If you could get the aluminum heads near free.
Also would require your time and actual swap.
The weight reduction is near a 10HP increase.
The head CC volume is a gain in compression/ potential power increment.
This would most likely. Turn into PROM tune corrections. Economically this would require you as the tuner. purchasing the pocket programmer.
Learn and burn.
The air flow is a equal stand still.