C3 69 spark plug question

[Jimmy B.]

Duke,

I need your recommendation. My rebuilt 69 350/350 (oem cam & lifters), bored .030 "correct pistons, is just about ready to be dropped back into my car. I am getting ready to acquire some AC spark plugs. Should I try to find some R44's or go with AC 45 or R45S? If it matters at all the car has, ps & AC which should get a lot of use here in sunny Florida.

Thanks for your help.

By the way my Pirelli P4000 Super Touring tires have arrived and I am waiting to get them installed on my 67.

Jim Blakely

[Larry M.]

Re: C3 69 spark plug question

Jim:

I think that the AC 45 or the AC R45S are your best choices. The AC 44 or R44 heat range plugs seem to be too cold for street use and foul out early. Even though they were the OEM plug recommended by Chevrolet.

I changed from AC 44 to AC 45 in my 1967 327/350 HP car a while back. The car runs better and the plugs haven't fouled out. I believe that John Hinckley runs/recommends the R45S in his 69 Z-28. This may be the best plug for you, and I think that they are easier to obtain.

I think that even Duke will agree. But we'll wait and see.

Larry

[Joe L.]

Re: C3 69 spark plug question

Duke,

I need your recommendation. My rebuilt 69 350/350 (oem cam & lifters), bored .030 "correct pistons, is just about ready to be dropped back into my car. I am getting ready to acquire some AC spark plugs. Should I try to find some R44's or go with AC 45 or R45S? If it matters at all the car has, ps & AC which should get a lot of use here in sunny Florida.

Thanks for your help.

By the way my Pirelli P4000 Super Touring tires have arrived and I am waiting to get them installed on my 67.

Jim Blakely

Jim----


IF I were going to use an AC spark plug, I'd use the R45 or R45S. However, you'd likely never catch me using an AC spark plug in a small block. I'd be using a Champion RJ8C or RJ18YC.

[Duke W.]

Re: C3 69 spark plug question

My recommendation is the R45 or equivalent heat range in the brand of your preference. I'm somewhat indifferent to the R45S. The extended tip offers extra fouling resistance, but there is an outside chance (quite far outside) that the piston domes could hit the ground electrodes.

Chevrolet never used extended tip plugs in SBs as OE, but many owners have had success with them.

If you're not concerned about judging, I prefer non-resistor plugs as were used in earlier years, and the NGK B4 and Denso W14-U are non-resistor plugs of equivalent heat range to the out-of-production non-resistor AC 45.

Duke

[Jimmy B.]

Re: C3 69 spark plug question

Thank you for your input, now I must decide which AC plug to get. Looks like a 45 for sure.

Jim