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gregsdrums

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Had fresh valve job done and now compression is 135 130 130 125 front to rear. Before valve job front 3 plugs were clean and rear 1 was black. Put carb kits in. Same after valve job and still runs unsteady. Top of pistons and cylinders looked good. Can't figure out what's going on with the rear cylinder...
 
Compression numbers look ok

Start with you ignition system and make sure you have good clean spark to all cylinders. I use a timing lite and clip it on all four wires. you should get a good flashing light at all engine speeds on all wires.

Then do the carbs.


m
 
Sounds like vacuum leak somewhere. Check the throttle shafts if you didn't during the carb rebuild. If not there, look the manifold over carefully. That's where I would start.

JACK
 
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