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#21
01-30-2019, 11:45 AM
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Quote:
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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#22
01-30-2019, 06:52 PM
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Thanks for all the help guys.
Today I re degreed the cam with the heads on first finding TDC with a piston stop. Low and behold I actually had the cam installed just under 106ICL instead of the 107 1/2 as though. Took it apart adjusted the lower sprocket, checked 5 times and in am now at 108ICL as the cam card suggests and my balancer is now lining up at "0" again. Thanks again for the help, this is pretty new to me, just want to do it right! Sent from my SM-A530W using Tapatalk
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1970 Trans Am, numbers matching, White, Auto, A/C, Owned since I was 15. 1973 Trans Am, numbers matching, Brewster Green, Saddle interior...Sold :-( 1978 Trans Am 400-4spd, non-numbers matching 400, Low compression daily driver, [email protected] 1/8 mile....Sold :-( |
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#23
01-30-2019, 10:24 PM
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I'm confused. What does the crankshaft gear have to do with the balancer/timing mark?
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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#24
01-30-2019, 11:06 PM
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More to do with the fact that I thought I had the engine at true top dead center using the dial indicator, when I slid the balancer on at that point it showed 4 degrees before. Except it all wasn't right, because I wasn't at TDC. This in turn also screwed up me degreeing the cam in the first place since I didn't find proper TDC. All is right now though! I'll always use the piston stop method from now on.
Sent from my SM-A530W using Tapatalk
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1970 Trans Am, numbers matching, White, Auto, A/C, Owned since I was 15. 1973 Trans Am, numbers matching, Brewster Green, Saddle interior...Sold :-( 1978 Trans Am 400-4spd, non-numbers matching 400, Low compression daily driver, [email protected] 1/8 mile....Sold :-( |
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#25
01-31-2019, 11:18 AM
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OK! Now I see, all good.
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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