Well I ripped the valve covers off of my 402 and found that there is 6272292 heads on them. They have manley valve guides on them and what look to be heavy springs. Are these heads any good, given a port job and bigger valves? I dont know anything about them, but this 402 sits in mygarage, and I was thinking either rebuild that or attempt to get ahold of a bare 454 block at the junkyard. Are these heads worht building? You guys know more about these things than I ever will, so your input is greatly appreciated. This motor, BTW may or may not go in the firebird, or maybe I can get the 81 I always wanted and put it in there.

Yes, they're a decent casting for a moderate-performance street build sort of thing, they won't make a high-HP race setup though. They're open-chamber, small port, medium-compression. They're better than most of the 454 heads, and will work fine on either a street 402 or a street 454 with a low-CR piston.

So could I conceivably build a 430 horse or so on these heads given a full port job and a cam around the XE274's specs with either a 454 or a 402? SOmething like 9.5:1 compression? Im looking to dip a car easily in the 12's, could this motor be used to propel a 3500 lbs car as a streetable driver? I just have fallen in love with the low end torque of my father's 454 camaro, which will absolutely rape me off the line, despite a 218/218 @.050 cam and stock oval port heads. That thing just pulls with a massive torque peak all the way through the gears, despite power falling off strong over 5000 rpm.

That seems reasonable...

Open chamber, large oval port, used on 70-78 402 and 454 engines. They will have 2.06/1.72 valves but can easily have 2.19/1.88 valves installed if not already done.

They're not the most popular choice of heads but will work well with some port work and larger valves.

Have them magnafluxed and pressure checked before doing any work to them.

Open chamber BBC heads are better because it unshrouds the valves. Compression ratio is increased with a dome piston. The large oval port heads have better bottom end power. My engine uses oval ports. The large rectangular port heads are overkill on a street engine. I wouldn't even consider using a set on my race car unless I had a much bigger engine or reved it over 7000 rpm.

Cool, I will have the heads ripped off next time I go home. I have a feeling I will end up finishing a motor before I even have a car for it. Appreciate the help, Ill let you guys know what I find.