59 flatty 47 model stock eng, new valves springs guides and seats, did it before and after valve job, new points and cond, set at 17, had it set at 12, same thing, been thru dist, working correctly, adv brake adjusted as should be and everything in between, same result,plugs are black, choke eng with hand somewhat better, blocked vac port to power valve(full rich). runs better ie no exhaust firing, backfiring out exhaust, not intake, I did put penney in exhaust crossover in block to keep carb a bit cooler, I read somewhere about exhaust wedges to keep exhaust from leaning out next cylinder, cant find it, any suggestions?
Welcome David. A few more things. A good condenser is hard to find nowadays. Grab yourself a few more and try them. Another look would be changing your coil. A blocked power valve is not really a good idea. Buy your parts from Max @ Vintage Speed. http://vintagespeed.com/ Lots of info here on the H.A.M.B. also on power valves. https://www.google.com/amp/www.hotrod.com/articles/0510sr-holley-94-vintage-carburetor/amp/ Next. Vac Brake. Hook up a meter to your vacuum. Adjust your brake to maximum vacuum, then back it off a few pounds. Other than obvious timing and proper plug wire placement this should give you some more garage time.
I got lucky on mine with the same problem. A carburetor switch out cured it. Never found the exact cause.
I think I'd start with a compression test followed by a leak-down test. I'd also be looking for a vacuum leak. Pete
Start with fuel pressure and your carb adjustments Vacuum readings at idle and off idle? Vacuum leaks? Coil good? Condensers are generally crap now a days Is the engine timed correctly? Timing advance working? Distributor installed and points set correctly? Wires on the right cylinders ? Right plugs being used? Base engine timing correct? If all this checks out do a compression test and leak down test. Any noise from the engine? Broken valve spring? Lots it can be, start with the simple stuff first and work your way up. K-keep I-it S-simple S-stupid Is it 12volt or 6 volt and is your coil addressed accordingly?
Typical of a flat cam lobe. Did you install new plug wires? Fire it up in the dark and look for cross firing. Check the dist cap for cracks or carbon tracking. A piece of thin sharp metal or carbon in the exhaust passage can set off unburned fuel, also. Firing order correct? Compression good on all holes?
got it fixed, this engine had a oil bath air cleaner originally, and they seemed to always have some restriction, so to check it i cupped hand over carb slightly and she ran correctly, rejetted carb one size larger, numbers gone on my jet drills, and she is doing good, gona watch plugs, might need some more, thanks for all the replys
Thanks for the follow up. What have you replaced the air cleaner with? Some Aftermarket air cleaners are terrible clog hogs.
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