Rough Running after Timing Belt Install

[Joe_Black]

You've contradicted yourself here. I know for 100% sure that all the marks on the pulleys, block, and belt lined up perfectly, WHILE the #2 was at TDC, so are you saying it's still possible that it's 180 degrees out of phase?

He's got a point here and I apologize for having missed it myself. In a four-stroke engine the piston makes two trips each combustion cycle so by setting the TDC at the exhaust rather than the compression stroke it would make a difference.

I'm hoping to talk to one mechanic friend tonight and will speak with another tomorrow for "second opinions".

EDIT: Okay, just got off the blower with a race mechanic who said to make sure after installing a new timing belt to manually turn the engine over twice completely and then re-check timing marks. Also indicated that loss of power and backfiring can come from being one tooth off in timing.

I've never rebuilt a V-configured DOHC but have done plenty of FIAT and Lancia twin-cams where I've had to use a spanner to keep the cams on the mark when installing a new belt. Depending on how you're eyeballing the marks this could be the problem.