Hi,

I'm thinking about some "new" heads for my 340 since my J's do have too much play in the valve guides. The rebuilt costs and an offer for these heads are the same.
What do you guys think? Is it worth it or not?

See attached a picture years ago with the TRW pistons at TDC....

The 302 heads are 318 small port i think, they would be a step backwards. best bet would be a set of the RHS X heads all done and shipped to you.

yes, they are for 318. But closed chamber, swirl port. To modify a 318 it is the first choice. But on a 340 as well?

302s will choke your 340. They are closed chamber, but they have smaller 1.78"/1.50" valves compared to the 340s 2.02"/1.60" valves. Not a good idea IMHO.

are you showing .074" above deck, or .026" below?

if they're above deck, you're stuck with open chambered heads.

if they're below, I'd get these enginequests or these RHS heads from hughes....

the enginequests will require magnum style rockers (~40-50 used, $80 new for stockers), the RHS's use stock LA rocker gear.

OOTB hughes has found an LA head with 2.02's (576 castings) flow ~212 cfm@ .500 lift, the EQ's flow 227, (with the smaller 1.92" valve) and the RHS X heads 252 CFM at the same lift...302 heads typically flow 135-160cfm on the intake side, and max out fully ported at about 140 on the exhaust...

oh yes, you are right. Pistons are slightly above deck. I totally forgot that.So I can't use these 302's.

no way, go magnum

The only way a 302 or magnum will work is if you can find a really thick head gasket to keep your piston and head at least .030 inches apart, if they are more than .020 out of the block then good luck with that

Other than that you can change pistons also.

A max ported 302 with big valves can make more power than a bone stock X head but not much