Quote:
Originally Posted by Colin70TA
Hmm, okay, didn't know that and not 100% sure where I had it. I have the heads on now, I'll check it again tomorrow with the heads on I suppose, see if I screwed up!
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How much the piston rocks depends upon the clearances and the ring fit, along with the wristpin offset of the piston.
When I first used a deckbridge, I noticed errors like described above. I then realized I could push towards the top then the bottom of the piston crown, and make the piston rock. Then noticed the piston typically rocked one way coming up, then the other going down.
Like a see-saw, you have a lot of movement at the ends, but virtually none at the pivot point (directly over the wrist pin). I'll measure some arbitrary distance, say 0.050" before TDC and again after TDC, and average to zero my degree wheel/find TDC.
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'73 T/A (sold). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 317rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'.
'67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust
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