Got a 57 Cadillac here that is all stock runs pretty good has a little rough idling. Timing is good has a pertronix in it and Autolite 85 plugs , going to do a compression test so I Pulled all the plugs to check them and they're all about the same except one. Seven of them are white and ashy on the electrode and one is a little bit red. Looking through online charts I can't really see anything in here except maybe the plugs are overheated. What are your thoughts?
Running too lean, incorrect plug heat range or retarded timing will cause plugs to become hot and white in color.
That's what I was thinking too. It does run fine doesn't have bad power and I can't find vacuum leaks anywhere. Going to put some new plugs in and search for some leaks and see what I come up with. Did a compression test it's equal across the board about 135 which is a bit low but they're equal so that's okay
Check your timing too. I’d slightly advance it. Don’t ignore the problem just because it’s running well. You don’t want burnt valves.
Someone may have screwed in the wrong plugs sometime. Entirely possible that every plug change since was plugs that match the wrong ones. I would check the numbers to be sure you have the right ones instead of way too hot. Just a thought.
Autolite 85’s are listed as the correct plug when I looked them up online and are extended tips, but I would go to an AC 44 as it was the stock plug and not extended. Today they say extended tips are better but were not stock in 1957. IMO Autolite’s belong in a FOMOCO not in any GM….
I just put a set of AC 45s in because I had them. Ran better but still a slight Miss. Found a bad plug wire and replaced them all and it's running smooth. Going to go drive it
Driving good but found that the balancer has slipped and it is retarded, don't know how much. Advanced it by ear a few times and drove it a few times and running a much better. Going to have to get the balancer rebuilt sometime soon before it completely falls apart
Damper Doctor in central California turns a damper around in a day after he has it. Pleased with his work. Was $150 when I had it done a few years back.
how many miles on those plugs? Look at this plug, 3 miles of wide open land speed racing...Lean or rich?
Can’t see the base of the porcelain. You need a light brown ring at the bottom. The first 2 threads need to have a blue coloring.. Personally the plug is to high a heat range. You need a lot less porcelain showing. what’s your compression?
You...TOO LEAN...guys don't see many spark plugs with a few miles on them do you ? As one guy above said, the jetting is VERY close ! AND...without seeing down at the bottom of the porcelain, you have NO clue where the timing should be. You only see the the ground strap...that's only HALF of the story ! Mike
Yes leaded racing gas. Aircooled O/T bike...run one jet size rich as a hope not to go into detonation and piston seizure...Set two two speed records that day..
The Jalopy Journal
