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nabilious nabilious is offline
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Join Date: Oct 2004
Location: minneapolis MN
Posts: 463
jetting?? warmed up 2.7L high end missfire

So before it blew up on me, the engine was perfectly dialed. Idle jets are 52's and mains are 140. After a complete rebuild its up and running with a couple exceptions. The only thing I changed was add a Mod-S cam in place of the regular S cam. the car has 36/35mm ports, S dizzy, ect. Now as I'm breaking it in, I'm noticing a couple of things that I'm having trouble eradicating. If I get after it in 2nd gear, 3rd, or any others, after the tack swings past 5.5k there is a slight miss as it winds out. The jetting was spot on before the rebuild, with the exception of the Mod-S cam. Could that mean its a little lean on top? baaaaaataaaaaataaaaaaaataaaataa. is what is sounds like, the 'T's' are the light miss. It use to be really crisp so maybe the little extra cam is enough to cause it to be lean? I have the timing set at 34 degrees @ 6k rpms and I've adjusted the valves ect.

One last issue, while trying to balance the carbs left to right, I cant seem to get rid of this wobbly engine note from 2.5k to 3.1k ...Whomp whomp whomp kinda sounding loopsidedness....if that makes sense.
Any pointers would be appreciated, Its so close to being right and my rebuild (my first went really well!) I'll include pics when I download them later.
Cheers,
Nabil
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'71 S track car, 2.7L & Webers forever!
Old 05-25-2010, 06:15 AM
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