fbc25el

Have you taken a compression test? Something ain't right. Can you post what the plugs look like?

ThisIsLivin

I like the Autolite due to the shorter strap and less chance for detonation and better spark exposure. I run the 3924's in my 524 with 10:1 compression with no issues on 93 octane. I have a big cam carbureted engine and I idle for hours down a river and I have no fouling issues. But I do have a multi-spark ignition. I also bought an otoscope from walmart so I can check the banding on the strap to make sure I had the right timing and heat range.

boostbros

if its an est with the square coil they are very hot but need a lot of power you probably need to add a relay i run a 540 on the rich side and never foul a plug but if it is weak you will

articfriends

iTrader: (1)

I run 3923s in most aluminum heads and never had a problem with fouling if tuned properly

H8TOLUZ

round coil

H8TOLUZ

I’m sure that old 502 was getting tired. I still feel like the carb leaks down when setting. The level in float bowl definitely goes down but I know some will evaporate.

H8TOLUZ

with similar compression and pump gas?

articfriends

iTrader: (1)

Ive ran them with10-1 on 93 and at 8.4-1 on pump gas and at 13 psi boost with 93, one of my favorite "cheap" plugs, I actually LIKE the projected tip because they dont foul easy. I ran a set of 3923s in my 548 w prochgarger for 100 hours, pulled them out at 40 or 50 hours and they looked good enough to just put back in. LOTS of idling too, Smitty

articfriends

iTrader: (1)

Ran 3922s in my 11.4 to-1 street car on 93 (455 pontiac), seemed sputtery, went back to 3923's