VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Spark Plug (216- 1940)

Looking for advice: For a 216 1940 Chev, the manual calls for an AC44, unable to obtain, currently using an ACR45S. Was told to use ACR43S
Don't know the difference. They look identical.
Any Help? Thanks.

1940 Chevrolet spark plugs. I have put over 10,000 miles on my 1940 since rebuilding the original 216 cubic inch engine. I run the AC 45 spark plugs. It is a little hotter plug than the AC 44. In 1940, both AC 44 and AC 45 are listed in the 1940 Chevrolet Master Parts Book. As far as running an original design AC spark plug, the original AC design is hard to find and quite expensive. However, I run the AC 45 "Fire Ring" spark plugs. There are many AC 44's and AC 45's an ebay. Sometimes you can pick them up for about $10-$14 plus shipping for a package of 8 plugs. You need to be patient on ebay or you will end up paying too much for the spark plugs. Email me if you have any questions.

Any of the AC plugs-#44-45 or 46 will work well.The higher the number the hotter the heat range of the plug.Cooler plugs last longer for high speed driving.Hotter better for cars that burn oil and are used mostly for low speed driving..I use R45 plugs in my cars-they are resistor type plugs and have had good sucess with them.
The S plug that your using were designed to burn off the lead deposits (leaded gas) .It caused problems in the late '50's and '60's - especially causing a high speed miss in V8 engines.The S plug will cause no problem in your 1940 but may not last as long.Would not recommend using an S plug in a 235 engine with aluminum pistons or a Corvair as they sometimes cause holes to burn thru the top of the piston.

Standard plugs are of much better quality and will last much longer today than their counterparts of 50 years ago plus will burn cleaner due to the unleaded gas.