I was going to order some new spark plugs for the 30 Roadster, but noticed the ones on the Filling Station site for 29 thru 32 years, were C 87's and the ones in my car are C 86's. Not sure why the difference? Should I swap out the 86's for 87's? If so what gap. Right now mine are about .030
When AC made them going from a C86 to a C87 would be one heat range hotter. A one heat range hotter plug should not make a difference unless you are planning high speed endurance runs. I would try them and see how they work and pull them and check their color.
With patience I have had good luck finding the correct AC made plugs on e-bay. Sometimes buying one or two at a time to make a set.
Lot's of info on Bill's 31 site that could be used to set your timing and plug gap. Some find the recommended gap of .040 too wide and adjust it slightly smaller through a trial and error process.
ps Lot's of good technical info if you are a member of VCCA on the members site. Did you get the shop and owners manuals with your car or from the filling station?
Thanks.....seeing that my plugs seem to carbon up quite fast.....although I have not really driven the car, just running it in the garage while adjusting the carb and tweaking the gap up from .025 to .030, ordering new plugs wires, coil and soon new plugs, hopefully eliminating the carbon problem, longer drives might blow out the soot. The old braided "show plug wires" are quite "crispy" and will be replacing them with correct copper center black lacquered ones.
Removed a plug and turned the engine over by hand, but could not fine the TBC marker on the flywheel. Must be pretty obscure. I wanted to line up the #1 with the rotor position.
That is why your spark plugs are carboming up ... just running the engine without a load will cause that. The burning the sparrk plugis judged under normal driving on the road.
AC C-86 would be the correct ones, they are hard to come by now and most use the C-87 as you can get those easier. I am running C-86 in my 1929 and have a spare set IF they are ever needed, have C-87 in my 1930 and a spare set of those. both run the same and work great :)
If you have the C-86 clean em up and run em, unless they are in bad shape.
AACA - VCCA - Stovebolt - ChevyTalk Love the Antique Chevrolet's from 1928-1932 The Beauty, Simplicity, History, and the Stories they Tell
Because of the shape of the combustion chamber on your engine the spark plugs will carbon quickly with modern gasoline especially when run at lower speeds, low loads and short duration.
Increasing the gap to 0.040" will help reduce the carbon as the higher spark and spark plug temperature will help with more complete combustion at the plugs.
I just sent you a private message as I stock all the ignition parts for the 1929-32 Chevy engines with 18MM spark plugs.
To everyone out there, we sell a premium quality oil filled copper wound 6 volt coil rated at 55.000 volt output priced at $50 that will easily fire a spark plug gapped at .040 inches.
