Correct AC spark plugs for 65 - 365hp

[David K.]

Want to replace my spark plugs on my 65' 365hp car (no AC). I have seen two sets (NOS) on Ebay this morning. The first is the AC 45 non resistor type (PN 1559493) with the thin green bands. They are dated 1973. The second option from the same vendor is AC 44 non resistor (PN 1559492) with the thick green band over three thin bands, dated 1980. These are GM NOS - not repros.
A bit confused as to the application - which set is correct for my vehicle? Also, is the age of these parts an issue?
Thanks in advance.

[Gene M.]

Re: Correct AC spark plugs for 65 - 365hp

David,
The Corvette was sold new with AC44 plugs. The green bands have changed over the years of production.

[Larry M.]

Re: Correct AC spark plugs for 65 - 365hp

David,
The Corvette was sold new with AC44 plugs. The green bands have changed over the years of production.

[Gene M.]

Re: Correct AC spark plugs for 65 - 365hp

I agree…………….but the AC 45 will probably be a better choice if your car is street driven and an occasional driver. I have come to this conclusion after trying both in my 1967 327/350 HP car.

During the mid-1960's these AC plugs had 4 thin green bands………………but both types you mentioned will work just fine, and you can't see the difference under the plug wire connector.

These plugs are also being reproduced………….but I have not tried these since I have two lifetime supplies of old stock (44 and 45) on the shelf in the garage. Others can perhaps comment on the reproductions, but I would think they would be fine. A number of Chevrolet and Corvette vintage car parts suppliers carry them.

Larry

Yes what Larry said.
There was, I don't think available any longer a non resistor extended tip plug. Good for non dome pistons but may be ok with L79 domes, I had not tried them in my L79's. Numbers were/are AC44S and AC45S. They are not totally correct but I have found the AC44S run well and clean in my 65 base engine with solid core Packard wires, 202 coil, extended tip rotor, and good points.