Quote:
Originally Posted by U47
All 69 350" 2bbl heads are cast #47. The valve sizes are 1.96 and 1.66 ( the intakes are larger than 60-61SD's (389's) and 63-66 H-O's (389 @ 421's) at 1.92.
The # 48 head for the 400" are 2.11-1.77 and the chamber volume is 72cc. with a compression of 10.75 to 1. The 350 # 48 has a compression of 10.5 to one. To me that means the 350 # 48 head has a different chamber volume than the 48 400" head, just look at the bore size difference 4.12 vs 3.88 ! That dosen't equate .5 in compression.
Don
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The 350 HO #48s are purported to be shaved @ .020 for @ 68 cc chamber as opposed to the typical 72cc 400 head. Stands to reason, as well. This I learned form a GM worker.