906 heads vs 516

[ir3333]

I have 516 and 906 heads. On a small cam 383 would there be a performance difference below 5000 rpm?

 

[33 IMP]

Probably not, unless the compression is too high with the 516s, causing detonation (frankly, not likely.).
Calculate you comp ratio with both.

 

[ir3333]

The 516's may have and edge at lo rpm?

 

[khryslerkid]

Some info...

What are #516 Big Block heads worth?

 

[Dave6T4]

Likely nothing you could feel in the seat of your pants. The 906 heads have better porting, but larger chamber would drop compression a full point. This would be helpful, if you are experiencing detonation. You may be able to drop back a grade of gasoline, saving you some $$$. 452 heads are like 906's, but with hardened exhaust valve seats. Chrysler used 906 heads on every big block from 383, 2-barrel, to 440, 6-barrel, 1968-1971.

 

[sam dupont]

do the 452's have seats, or a hardener applied to the heads? If applied, does it go away with every surfacing or with extended use??

 

[F4R/T]

They maybe induction hardened I can’t recall for sure...

 

[R413]

Depends on your pistons, then you,chose the best head for compression ratio.
What year is the block, is it standard bore or over bore?
Is the piston tops flat, dished or valve reliefs on top?
Is there any numbers stamped on top of the piston?
Is the short block together, how far down is the piston at TDC?

do the 452's have seats, or a hardener applied to the heads? If applied, does it go away with every surfacing or with extended use??

Only the exhaust valve seats are hardened, not the head itself.

 

[Don Frelier]

Any 906 head should be age hardened by now.

 

[sam dupont]

I delved deeper and 452 heads don't have seats installed. They are thinly hardened. It can be completely removed with one grinding

 

[F4R/T]

Induction hardening only goes so deep. You could always install seats I guess.

 

[sam dupont]

It sounds like manufacturer think. What can we do to get heads past warrantee?