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seafoam56 09-19-2008 08:48 AM

engine has quick miss
 
Hey
i notice that my engine has a miss in it...i watch the tach as it idles at 600rpms i notice it dips to like 550 every few rotations...could this be an ignition issue...its kinda like a miss fire....you can hear it in the exhaust...or could this be a carb/gas problem...open for thoughts.
thanks

Jmark 09-19-2008 08:55 AM

It could be either an ignition problem or a fuel problem. (yea, I know, real good answer! LOL)

It could be a plug misfiring from being a tad lean, or worn, or partially fouled, or a wire breaking down too.

It could also be an occasional drip of fuel from one of the primary carb nozzles, momentarily fattening up the mixture. You can look down the carb with a flashlight and watch for the drip.

The ignition problem may take a little more checking.

seafoam56 09-19-2008 11:07 AM

Well the engine is running really rich...it seems like no matter what i do with the carb it runs the same...everything is brand new...its a crate 350/400 horse...once on the road moving it seems fine...but its been that way since i had it running...I will check the plugs and see if i can notice anything

oldbogie 09-19-2008 02:21 PM

Quote:

Originally Posted by seafoam56
Hey
i notice that my engine has a miss in it...i watch the tach as it idles at 600rpms i notice it dips to like 550 every few rotations...could this be an ignition issue...its kinda like a miss fire....you can hear it in the exhaust...or could this be a carb/gas problem...open for thoughts.
thanks

I wouldn't worry much about an idle miss if it goes away as soon as the revs pick up. Fuel distribution at idle is never very good with a carb, and this being a 400 horse 350 it's pulling some cam and has a somewhat over-sized carb. This is recipe for an idle miss, especially if combined with an unheated or single plane intake manifold. Probably the easiest solution is to speed it up a little bit.

Bogie


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