Originally Posted By BSB67
Originally Posted By JohnRR
Originally Posted By BSB67
Originally Posted By cudaman1969
NHRA piston guide,
69 440- .027 below deck
70 440. .051 below deck
71. 440 .051
72. 440 .123 below deck

67 440 .059
68 same as 69


Those numbers actually line up well with what I said, minus 1970.


Common core math maybe wink

10.725 blueprint RB deck
6.768 rod
3.75/2 = 1.875 crank stroke

68-69 2.03 piston is .052 in the hole
66-67 2.00 piston is .082 in the hole

I'm not sure what 70 is because NHRA spec is different for 70, which has 2 piston specs 440-4 and 440-6pk.

The 44- 6pk in 70 is the only piston number where NHRA and factory actually match up, 71???


My math goes to the ratio of the piston depths or CD that were posted to the piston CH that I listed. I intentionally stayed away from the whole deck height discussion. But without that clarification, my comment was indeed unclear.


I used the deck height to drive home that NHRA spec and ACTUAL specs are not the same ... You had the actual piston CH , which are not available in the aftermarket currently , and haven't been for quite some time , if at all ...

running up my post count some more .