[BG383]

Question: I have a crate 383 stroker (360hp/410lbs) on Sealed Hyperutectic Pistons(yields 9.5:1 CP, flat top, 2valve relief); GM Cast Iron heads (Valves: 1.94int/1.5exh)(72cc/170 runners)...Compressed Head Gasket of .041..Standard deck height..Comp Cams Hydraulic Flat tappet .477/.480 lift; 110 lsa; 224/230 dur. @0.50" Advertised Dur. 268/280. I want to run Aluminum Heads (preferable trick flow's, AFR, Dart) with 190 or 195 intake runners & 2.02/1.6 valves. What size Combustion Chamber should I use to keep a CP ratio of nothing greater 10.5. (Street Driven/ Maybe some Track car).....Thanks

[techinspector1]

It's your "standard deck height" statement that would concern me. Depending on piston compression height and machining of the block at the factory, this could be as much as 0.025". Added to the head gasket thickness of 0.041", this puts squish at 0.066". I think I would measure the piston deck height. If it's 0.025", use a thinner gasket to tighten up the squish.

Assuming you're using a 0.030" overbore and flat-top piston with two valve reliefs, here's how it would work out for c.r......

Cylinder 784
Chamber 65 (AFR 195)
Gasket 5.4 (Victor Reinz #5746, 4.100" X 0.025")
Piston eyebrows 6.6
Piston deck height 5.2 (@ 0.025")

Total volume 866.2, compressed volume 82.2
Divide and get 10.53:1 SCR with 0.050" squish.

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