99 challenger 1800 no power after rebuild

[saint1000]

as the title states i have a 1999 challenger with twins 787. both engines were fouling 1 plug while the other plug looked good. both engines were stalling and not making much power. pulled the exhaust valves and found 2 broken valves on the cylinders that were fouling the plugs. so i got new pistons, 4 new valves and rebuilt the motors. there was no damage to the cylinders. put everything back togeather. motors start and idle fine, but when giving throttle still making no power and the same cylinders with the broken valves were fouling the plugs. checked spark and there is almost no spark on the cylinders fouling the plugs and the cylinders that were not fouling plugs have what looks to be weak spark at best. could this be a coil even though they use 1 coil for both cylinders. do both cylinders fire at the same time this way? going to check recitifier tonight and some other checks but anything else any one can suggest to check. the problem seems to be amplified after the rebuild.

 

[Dr Honda]

Yes... it fires both plugs together, but if the coil is damaged... you could be leaking HV power to ground somewhere else. I would try to trim back the wires a little, and put them back on. Sometimes the inside of the spark plug wires corrodes.


What's the compression on the engine?

 

[saint1000]

Compression is good. Over 140 on all cylinders. I pulled the wires from the coil and spark is weak at the coil also.

 

[parrothd]

So you rebuilt the entire engine and didn't bother rebuilding the carbs and fuel system?

 

[saint1000]

carbs were rebuilt last year with new diaphrams and accel pump diaphrams. accelerator pumps are not sticking and seem to squirt normal. i really think im chasing a weak spark issue.