Thread: 305 with 350 high proformance heads

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how good would a 305 with 350 heads be, would it be a good motor to beat on or will it give out. i am asking because i am looking at buying a motor and i have the option of buying a 4 bolt main 350 or a 305 with 350 heads. i am told the 305 will be fast and snapper but i think a 350 will hold alot better. please help me. mongoose

The stock 305 came with 58 or 61 cc combustion chambers in the heads and had deeply dished pistons. The 350's pistons are not as deeply dished and they came with heads with chambers of 62, 72, or 76 cc's. So, if somebody just bolted a set of large-chamber 350 heads on that 305 without changing the pistons, the compression ratio will actually be lower than stock and it will be a real dog.

I have never heard of a 305 being "snappier" than a 350. They have the same 3.48" stroke, so the rpm range is similar for both engines. Remember the old axiom: There ain't no replacement for displacement! Take the 350; it will make you happier to start with and you can do more with it.

thank you for the reply but i dont know what all they did to the engine but i thought they were full of it when they were telling me it was better than a 350 thanks again.

as far as snappier than a 350...depends, a stock 2 barrel 350 ? stock late 70s truck 350? not all 350s were fast. the 305 I built for my Caballero ran 13.70s...thats snappier than alot of 350s,of course $ for $ a 350 would be faster.
350 heads on a stock piston 305 would only be a good thing if there small chamber Vortec heads or L98 aluminum heads.

tech, yep, gotta stay within 1.94, or 2.00 with GM fastburm head on a 305, can relieve top of cylinder near exhaust valve, helps a little there to.

so what ur saying is that the poeple who put the 350 heads on that 305 just didnt think ahead and the engine is no good right because they have out of the truck and told me i would be buying it as is so pretty much it wont work right.
mongoose

They probably did that because the 350 heads are more readily available....

If your stuck with the factory 305, just buy a set of remanufactured heads, shave em and you'll be a lot happier. If you want to hop up the little motor, try a higher lift cam(not astoundingly high) and a set of non dished pistons for a start. Your not going to get massive Hp gains, but you can build it enough to have some fun with it