540 BBC running poorly
 

1991 Cigarette 35 Cafe Racer. Twin 540s built by White in TN. 34 hours since built.

I pulled the motors in August in order to replace both transom assemblies.

Everything is reassembled now. Motors not running well. The motors both backfire through the carburetor if base timing isn't well above 25 degrees, which is way too high.

I pulled all the plugs today. Most look ok, some are white and look almost unused but many are dark, some sooty, and some wet. It seems like they should all look similar, but they don't.

I will attach pics of the plugs shortly.

One more.

How much dust got in your carbs :) or dist cap ?

Good question. Could have been a lot. They were on my garage floor for 2 months.

what ignition system?

How old is the fuel in the tanks?
Is this last years gas or was new gas put in and the boat run this summer?

Both engines have the same problem so it has to be something common to both. Fuel...

MSD distributors and marine 6m-2L boxes. Mallory coils.