351 Clevo Misfiring beyond 3500-4000rpm. - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Ramrod429 · 06-09-2003, 03:49

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.

johnny r · 06-09-2003, 04:03

Check your power valve, depending on holley you might have 2, one front, one back. Why did he try and run methanol, with standard carby?

johnny r · 06-09-2003, 04:09

Also have a look at rotor button, distributor cap, I would change distributor cap, may be cracked or faulty.

Ramrod429 · 06-09-2003, 04:09

correction sorry i meant that cheap leaded stuff with ethanol in it.
Not methanol my brain got a few lines crossed. We'll have another fiddle with the holley and see if it plays out tune.

Ramrod429 · 06-09-2003, 04:12

Rotor and distrubtor cap are two days old. Methinks the Holley or the Vacuum leak somewhere is the bloody culput it could explain the excessive fuel consumption. We ripped out the entire dizzy and chucked it in a XA 351 and it kicked over sweet. So all those Holley engineers were looking for you! Then again the timing may be out also.

johnny r · 06-09-2003, 04:19

had problem once with my 351 flooding. changed front float, had pin hole, float was filling up.

Ramrod429 · 06-09-2003, 04:44

hmm excellent point that could well be it. Don't know how that could die but i suppose it misfired with a big show so it could be shot to bits. Get back to you tommorrow with the news too bloody tired to look at it now as we've spent from 1pm-5pm on a perfectly good arvo on a public holiday with the beer fridge all out.
it may well be 'one' of the culprits.

johnny r · 06-09-2003, 05:05

just another one, i remember one time in a falcon i had, i put a set of new leads & plugs, and when i started up it was running rough. drove it around that day and it was missfiring and used alot off juice, found that i had put two leads on wrong, can't remember which ones but i think it was No. 8, No.6

brenx · 06-10-2003, 01:08

I just thought I'd add.

Hows the distributor shaft bushes look? Could be the dizzy shaft floating @ high rpm.

I've seen quite a few dizzies with worn out bushes.

Brenden

Ramrod429 · 06-10-2003, 02:41

Many thanks we worked out the problem. The points in the distributor were knackered real bad and H-T leads 5-7-8 were slightly if ever so frayed that when it got it got to a certain level it really had the sh*%s and misfired at high rev ranges and sucked gas big time. It was quite a simple problem when you look at it but you'd never expect it either. Big thanks to Johnny R he got the nail right on the pin ! Many thanks to everyone for their help its much appreciated!

Danny