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454 merc backfires out of carb

dozerman161

New member
PLEASE HELP
I have a 91 BAJA


PLEASE HELP
I have a 91 BAJA 260 that I purchased and it was running rough then so I got a deal or so i thought.
454 merc engine was overhauled last year but do not know anything else.
During start up it backfires out of the carb alot of times. When it starts it seems to run well but if you rev it then shut it off it is always hard to restart and backfires. The timing has been checked several times with a cheap timing light and the engine will not start or run if it is adjusted anywhere near 8 it will only run and start if it is way advanced like around 25.
Heres what ive done so far to try to repair it
1- changed intake gaskets
2- changed plugs
3- swapped carbs from a truck it was a 750 eldebrock
4- installed an HEI distributer
5- cleaned carb several times
I am not a v8 mechanic I fix air conditioners and repair motorcycles for a living so let me have it!
 
Yes checked it a couple times

Yes checked it a couple times and its wired like printed on the intake manifold. 18436572 (I think)
Any other ideas?
 
"Is it possible for the rotor

"Is it possible for the rotor to be installed 180 degrees off? Also, if it was overhauled last year, it's possible that the distributor went on 180 degrees off. If you can remove the valve cover from the odd cylinder head, rotate the motor manually and look for the #1 intake valve to open and close. When it closes, move the crank to TDC. Then, make the rotor line up with the #1 plug wire. "
 
I had the rotor in 180 out at

I had the rotor in 180 out at first and then corrected it.
Timing chain issue? Do you think it is stretched or a tooth off or both? I dont know but that was my next guess but didnt want to pull every thing off unless I was sure.
 
"If it was overhauled last yea

"If it was overhauled last year, maybe they put the chain on a tooth off.
I would go over the timing and firing order again, if that seems ok I would have to assume a chain problem."
 
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