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shogun

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"I have one motor that backfir

"I have one motor that backfires only above 2500 rpm is it a vacume leak,? fuel restriction?"
 
"Might be crossed plug wires.

"Might be crossed plug wires. Warm the motor and idle it at 1,500 rpms. With insulated pliers and heavy gloves, pull one wire at a time out of the distributor cap, then replace it. The motor should slow then pick up as the wire goes back in. If not, that cylinder is not firing. If you find two that way, switch the plug wires at the distributor.

Good luck!

Jeff"
 
Thanks again Jeff I did have

Thanks again Jeff I did have 3 dead cylinders so I replaced the intake valley pan and the Carb gaskets all the wires and now it seems to have only 1 dead cylinder will the water still look the same with one dead cylinder? also at 2500 rpm underway on a load the carb starts to back fire any idea it doesn't do it until I reach 2500


Mark
 
Check for a cracked distributo

Check for a cracked distributor cap...run the motor in darkness to visually check for any external cross firing from the wires...check for play in the distributor shaft....run a compression test....remove valve covers and make sure all valves are opening and closing. Also check for any worn cam lobes...all of these things could cause a high rpm backfire through the carburetor
 
"will the water still look

"will the water still look the same with one dead cylinder?"

I'm confused. What water? You don't have water in the dead cylinder do ya?
 
The water coming out og the ex

The water coming out og the exhaust seems to be airated and has a little brown color to it. totaly different from the port motor
 
"So the plug fires at a higher

"So the plug fires at a higher RPM. Could be bad plug, bad wire, burnt contact on distributor cap. Seems like a high resistance circuit or a pair of wires are mixed up."
 
Possibly a blown head gasket a

Possibly a blown head gasket allowing combustion gas into the water jacket and some water into the cylinder on the intake stroke. Run a compression check.
 
Thanks for everyones ideas I t

Thanks for everyones ideas I think I fixed it we did have 2 wires crossed and reset the timing and she seems to be fine thanks again
 
I did a compression check and

I did a compression check and all cylinders were from 142 to 148 all seem to be ok there However I did have two wires crossed and a vacuum leak I fixed all that and its running great now Thanks for your input
 
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