Correct spark plugs for 63

[John S.]

What is the correct spark plug for a 63, 250HP engine?

I ordered a set from Corvette Central and got AC 45S, are those correct? I thought AC 44 were the right ones.
Any help on this?
Thanks,
John

[Joe R.]

Re: Correct spark plugs for 63

The 45's are a little hot unless you have an oil burner. 44's would be my choice for normal street driving and 43's for autocross etc.

JR

[Larry M.]

Re: Correct spark plugs for 63

Although I generally find myself agreeing with JR, I think you will be fine with R45S.

Even back in the day, 44 plugs were a bit too cool for the street and would foul. Especially apparent if you were in a race and didn't check/change your plugs first. Many folks (self included) switched to 45.

All AC plugs since the late 1960's are the R or resistor type. This is okay. The S indicates extended tip. Also okay, especially for the non-SHP engines.

I have about a dozen boxes of vintage AC 44 plugs for my 1967 327/350 HP car on-hand, but run AC 45's in it currently. PS: It burns no oil

Larry

[John S.]

Re: Correct spark plugs for 63

I am mainly looking for what will pass NCRS judging, got dinged on plugs, so not sure what is needed there.
Thanks,
John

[Larry M.]

Re: Correct spark plugs for 63

I am mainly looking for what will pass NCRS judging, got dinged on plugs, so not sure what is needed there.
Thanks,
John

John:

I didn't think we had digressed to that level of detail yet. I'm generally okay if I just see an AC plug with green lettering/rings, regardless of the heat range.

But for judging, you need AC 44 plugs with 4 equal/thin green rings at the top. They are about $40-50 a box and can be purchased from various ads in the Driveline or on Ebay. Not three rings......not four rings with one thick one, not all white, but four equal/thin green rings

Larry

[John S.]

Re: Correct spark plugs for 63

John:

I didn't think we had digressed to that level of detail yet. I'm generally okay if I just see an AC plug with green lettering/rings, regardless of the heat range.

But for judging, you need AC 44 plugs with 4 equal/thin green rings at the top. They are about $40-50 a box and can be purchased from various ads in the Driveline or on Ebay. Not three rings......not four rings with one thick one, not all white, but four equal/thin green rings

Larry

Larry,
So just AC 44 and four equal thin stripes with no other number/letter? Not extended reach plugs. A pain for just one deduct point, but guess I have to be correct.
Thanks,
John