Which heads?
So I am trying to get an engine together for my sons 67 Dart. The original 273 engine is seized after sitting for years, so I bought a good used 1976 360. I bought a summit 6901 cam, performer intake, hooker headers, and speed demon 625 carb. Should I use the 67 273 closed chamber heads to boost compression or should I use the original 360 heads? I have blown up my brain trying to figure this out. I’m not changing pistons or anything like that just want the best bang for the buck. Thanks
Best wishes for you and your (how old?) son with a 360. Hopefully he is responsible with power (see Mustang crashing videos)
My low-level recommendation (KISS) is to either
recondition the cylinder heads, or buy the chinese Speedpro/Speedmaster aluminum heads assembled & have them checked out at a machine shop.
First option, call up summit,
get valve spring recommendations,
the giant c clamp removal/installation tool ($100),
remove valve springs and retainers
(AND KEEP TRACK WHICH VALVE/SPRING/RETAINER GOES WITH WHICH HOLE ON WHICH HEAD),
bring the heads (bare) to the machine shop, have the shop perform a valve job,
ask about hardened seats, ask about valve condition,
have the shop verify valve spring retainers or replace them,
install valve seals (Viton??), and
either they assemble the heads for you or you take the clamp are reassemble them yourself after one more extra cleaning, drying, and then lubrication.
after these two choices, and if unlucky, during these choices, cylinder head options can be expensive.
keep it simple sir!
Another option is the dodge 318 (1980's) '302' cylinder heads refreshened-without porting they would govern the rpm's of your son's driving due to less air flow but increase torque with the smaller, closed chamber, cylinder head. Mopar official would port them for you for more air flow.
the 273 cylinder heads MIGHT not bolt up to the later LA if it is an early enough engine as I understand the members here on FABO SBM