351 Clevo Misfiring beyond 3500-4000rpm.
Fourtunately this ain't on my Mustang it on my mates car though im still worried all the same. He has a 71 Fairlane with 351 stock, C4 and 9 inch for starters. This is where it gets fun, he dediced to put some methanol in it because it was cheap and not long after it got real sick. He gave it a bit at the lights two days later and bang, bang crack. We took it in the garage and pulled apart the carby and checked the timing, which was correct. The HT leads were checked as spark plugs and the dizzy so we were further stumped. We later on completely dissessembled the distributor
and we replaced the 4 barrell Holley with another. Advancing the timing further than stock by 10+ actually made it misfire less which we found quite strange. So it would go past 5100rpm then misfire with much gusto. The back two barells one the carby are flooded which is strange when the car stalls- really flooded! We murdered two carbie gaskets in the process. We check the carbie for vacuum leaks which we found none which we hope as we have used 3 and 1 with a complete carby rebuild kit which is now doing the same thing !!!
It was also consuming a prodigious amount of fuel in the process consuming half a tank in less than 20km and blowing excessive smoke which I must say is quite unusual for a ground up rebuild Cleveland.
Upon inspection of the carby we found it to be dripping in fuel so we automatically checked the fuel pump then replaced it. It worked fine for a while then it flooded again, misfired. This has got me absolutely and totally stumped and makes me feel like slapping him across the face for buying dodgy fuel and as a result we have to source another 351C before next week while we attempt to rebuild this one hoping there is no severe damage which we think is minor as all cylinders fire up it is just beyond the certain above rev range it gets hairly and not long after floods and misfires. Any thoughts and ideas no matter how silly are welcomed as we may have missed a silly one as well.