What's the REAL Compression Ratio for Stock 69 440 HP??

[wyrmrider]

The factory warranty program may have paid for the r&d but the problem is the same for any open chamber mopar
remember I'm talking street not race only builds with a narrow high rpm power band
need a wider power band then still works to add some lower end of the power band torque

 

[Dusty997]

Do you want to be able to use 87 octane or ok with using 93?

Sorry for the Necromancy....but if one wanted to be able to use 87 what pistons would be the go to?

 

[V_TastyTacos_V]

What oem flat top piston was ever that far in the hole for a 383?
I've had a couple 383's that have those low CH flat top replacements.

The 383 in my Charger has pistons .140" down. Something like 7.3:1 compression.
Think I found why my car's a gutless turd.

 

[TorRed]

Deeply interesting information here! So who sells these pistons that enhance quench with open (906) heads? For a 383?

 

[dvw]

I built a 440 for a friend. He wanted it near stock with a very smooth idle. Used quench dome pistons. Equalized the depths of all the open area of the chamber. set it at .040" quench. Did the bowls and put 30 degree intake seats in them. Used a small 214@ .050" cam. Stock intake, carb, air cleaner and exhaust manifolds. True 9.7-1. it rattles a bit on 93 octane in the summer at full 36 degree timing setting. Other than that it runs really nice. Should have made it 9.5-1
Doug

 

[BSB67]

I built a 440 for a friend. He wanted it near stock with a very smooth idle. Used quench dome pistons. Equalized the depths of all the open area of the chamber. set it at .040" quench. Did the bowls and put 30 degree intake seats in them. Used a small 214@ .050" cam. Stock intake, carb, air cleaner and exhaust manifolds. True 9.7-1. it rattles a bit on 93 octane in the summer at full 36 degree timing setting. Other than that it runs really nice. Should have made it 9.5-1
Doug

That’s good info Doug. Do you recall what the cranking cylinder pressure was.

The one engine that I am familiar with is very similar to the one you described in the same mid-west type elevation, but with a 220-ish cam. On the edge at 9.5:1, and blew about 160 psi, IIRC.