good heads

[k10lt1]

i just bought a piar of id #12551561 96 lt1 heads are these heads a good pair? i currently have cast iron heads. can anyone please fill me in on some info on these heads i cant really find anything on them. thanks for the help.

[Kevin - Blown 95 TA]

Well aluminum heads pull the heat out quicker quicker than iron heads so you can go more compression, more timing before detonating, but the iron LT1 heads are said to have slightly better flow numbers than stock alum heads. Net result is that the aluminum head engines are slightly more powerful.

[Injuneer]

Here's a good article on the various parts used in the LT1's:

Rebuilding the LT1

A quote from the article:

There were two heads used on the 350, one aluminum and one cast iron, along with one cast iron head for the 265. GM claimed that the original LT1 aluminum head had a 15% increase in airflow as a result of revised port angles and higher port ceilings when compared to the 1991 L98 head. That was impressive in 1992, but the iron LT1 head that came out in 1994 was even better. It flowed 20% more on the intake side and made more horsepower on the dyno.

All LT1 heads used small combustion chambers to get the higher compression ratios with flat top pistons; the 350s had a 10.5 to 1ratio and the 265s had a 9.8 to 1 ratio.

350 IRON HEADS - All of the full-size cars came with iron heads. They were 10125320 or 12554290 castings.