440 Compresion Guestamite

[Magnumgt]

Hey,
I am looking at a 70HP2 short block,
bored 30 over with sixpack pistons
(4 eyebrow type) - any body have an
idea or guess as to what compression this
combo will give with stock 906 heads?
any recomendations on milling heads and
what gaskets to use?

Thanks all!

[Marc]

True compression wil probably fall in the 9.5 to 10.5 range. I'd run Fel-Pro composite and cut the heads .030. This will account for the .040 gasket as opposed to the .017 steel shim job.
Just my .02

[440 Jim]

Back when I was selecting pistons, I talked to the guys at Jeg's about TRW replacements for the 440 six-pack. The TRW's are L2355F-30 for 0.030 oversize. TRW lists them as 10.4 CR, 2.061 compression height with 4 valve reliefs, 872 grams.

My calculations (with assumptions) are:
Bore 4.350
Displacement per cylinder 55.7 in3, 913.3 cc
Gasket bore 4.410 (Felpro)
Gasket thickness 0.039
Gasket volume 0.596 in3, 9.8 cc
Deck height (440) 10.723
Piston to deck at TDC 0.019 in.
Cylinder volume at TDC 0.28 in3, 4.6 cc
Valve relief size (est) 8 cc total
Cylinder head combustion chamber 86 cc
Resulting Compression Ratio: 9.4


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440 Jim
E-Body Fish