convert my 331 poly to a hemi

[56windsor]

What does it take to make the conversion from the poly to the hemi? The engine is out of a 56windsor.

[392heminut]

You will need a set of 331 or 354 heads, hemi pistons, pushrods, headbolts, rocker arm setups (rockers,shafts, stands, etc.),valvecovers,exhaust manifolds or headers, intake manifold, and a water crossover & thermostat housing if you use the later type hemi heads and intake which didn't have the water crossover in the intake.

[George]

What you basicly have is a 55 331 Hemi block. If you get 55 331 or 56 354 heads & use the stock water pump it bolts right up to the heads & block, You woudn't need the crossover. A better plan is to get adaptors & use the Chevy W/P. The long BBC pump will fit over the stock timing cover & then you bolt on the water crossover for the 392.

[challengerman]

Being new to the list I can't say I know a lot about Chrysler motors but it seems to me you would also need the hemi camshaft wouldn't you?

[392heminut]

No, the camshaft is fine, it doesn't know if it's pushing on hemi rocker arms or poly rocker arms.

[challengerman]

Hi, I'm not disputing the correctness about the cam in an early block but it makes me curious why the RB and 426 hemi show seperate camshaft listings. I can only assume the valve layout would be different in the later hemi motor. Does that seem right?

[392heminut]

I believe the difference on the later motors was that one used a single bolt timing gear and the other used a three bolt timing gear.

[firepower354]

The RB has a different valve layout(eiieeiie vs ieieieie), and thus a different cam is needed.

[392heminut]

I knew I was forgetting something about the RB-426 Hemi setup that had to do with the cam! Thanks for clearing that up for both of us Firepower!

Sheesh, it's hell getting old.

[buzzworm]

what makes the 331 hemi pistons different than the 331 poly pistons? Relief cuts?
I have also seen info saying you have to change the rods, but no explanations as to why/

[George]

Valve reliefs on a Hemi centered across from each other. On the Poly they are offset. Rods are the same.

[buzzworm]

so I am going to have to take my makita grinder to my poly piston tops (hehheh)