304 heads?

[Yoder]

will 1974 304 heads fit on a 1977 360?

[Chero77]

They will bolt on--but the valves in the 304 heads are much smaller than the valves in the 360 heads. This probably a swap that is best avoided.

[Manhattan]

I had a 360 with 304 heads. It was insane - probably 315-325 hp. The guy that built the motor only builds 360s and only uses 304 heads. I don't know enough of the "why", I can just attest to the results. This is worth investigating.

[hippymill]

smaller valve cavity gives more compression?!?!

[carrotman]

The 76 TSM lists the CR of the 304 as 8.4:1, and the 360 as 8.25:1. The 304 bore is 3.75, and the 360 is 4.08. The combustion chamber volume is equal (57.42 to 60.42 for 304, 58.62 to 61.62 for 360). Intake valves for 304 are 1.787, 360 are 2.025. Exhausts are 1.406 for 304, and 1.680 for 360. There might be more velocity with the smaller valves which could produce swirl and better scavenging.

[Kris]

Originally posted by carrotman:
...There might be more velocity with the smaller valves which could produce swirl and better scavenging.Yes !
Bling, Bling, Bling, Bling, Bling... We have a winner ! :D

The top end will suffer though.
The gains at low rpm are there to be haddue to higher port velocity, but at the expense of top end. 360's do just fine with the larger valves so there in really no need to swap unless you have them sitting around.

If I was building a commuting (good mileage) motor in an otherwise stock daily driver, I would look for some 304 heads.

For any use other than that, they are not worth it. You would need to goto a pretty tall cam to get your top end back, but then you get into custom valvetrain expenses...

kris.