C2:67 Spark Plugs-What's the difference

[Gerard F.]

in AC 44, AC R44, or AC 44S spark plugs? What's correct for a 67/327/300?
Are they all supposed to have 4 green stripes?

Getting a new set of repro plug wires, thought I'd get the right plugs for them.

Jerry Fuccillo
#42179

[Rob A.]

Re: C2:67 Spark Plugs-What's the difference

Jerry,

With regard to the stripes, they originally had four, equal, thin green stripes. You'll see some on ebay that are advertised as NOS, but they have one thicker stripe, and are not.

[Joe L.]

Re: C2:67 Spark Plugs-What's the difference

Jerry------

The AC R44 is a resistor version of the AC 44 spark plug for radio suppression. Resistor plugs started to be used pretty much across-the-board in 1969, although a few had been used much earlier (53-55 Corvettes were actually the first Corvettes equipped with resistor spark plugs). Resistor ("R" prefix) plugs were generally not used in Corvettes prior to 1969, though.

"S" prefix AC plugs indicate an extended tip. These are generally used to minimize spark plug deposit build-up.

The original standard service plug for 1967 Corvettes with 300 hp was the AC 44.

[Eugene B.]

Re: C2:67 Spark Plugs - AC 44

Gents,
When I purchased new Delco tune up parts for my '65 a few months ago, I was told by the local Delco distributor (in Columbus, OH) that the R44 spark plugs were discontinued. I had a choice between 45's and 46's. I chose the 45's.

Maybe you guys know of another source of AC44's other than eBay?

Best regards,
Gene

[mike cobine]

Re: C2:67 Spark Plugs - AC 44

If you want plugs to drive, then go with the AC 45 or AC R45. The AC 44 is a bit cold to drive around town. You can buy these about $13 a pack.

You can find original AC 44 plugs on eBay and some private vendors at swap meets. However, the private vendors are high, very high, frequently in the $40 - $60 range. EBay isn't much better, but occasionally you find them in the $30 range.

You also have to check as someone said here already that the plugs you get are the four thin stripes as opposed to the three thin and one thick stripes, if you are looking for show.

You are not going to notice any difference in how the car drives, other than the 44 plugs will tend to foul in city driving.

Others that will work usually are the 44S, R44S, 45S, and R45S. If you have high dome pistons, the -S plugs may hit.

My feeling is there are far too many AC 44 plugs showing up on eBay to be worth the price many are paying.

[Rick S.]

Re: C2:67 Spark Plugs-What's the difference

Jerry,
I have read in earlier posts that repo plug wires (Correct date coded) are fine for judging purposes but terrible for everyday driving. I would check the archives or maybe someone will chime in on that issue.

[Gerard F.]

Re: C2:67 Spark Plugs - AC 44

Mike,

Are there some problems in driveability with the repro plug wire sets.
Ordered a dated set from Lectric Limited. Would an R plug work better with these wire sets. I have my original 67 coil.

Jerry Fuccillo
#42179

[Donald M.]

Re: C2:67 Spark Plugs - AC 44

Mike, "High dome pistons" meaning those in a HP small block or big block, not base 327/300?
Thanx
Don

[mike cobine]

Re: C2:67 Spark Plugs - AC 44

I've never heard of anyone I've known with the stock 11:1 pistons having a problem with the plugs, however, there were constantly magazine articles on indexing plugs which implies someone must have. Even then, it is the ground electrode that hits, not the center electrode.

Of course, using true high dome pistons like for the 12:1 and 12.5:1 involve usually aftermarket pistons and they may have a problem with the -S.

A lot depends on if the heads have been milled, how they have been milled, what gaskets you are using, type of pistons, and so on.

[mike cobine]

Re: C2:67 Spark Plugs - AC 44

There have been a few on here who have complained about the repro wire sets as to drivability.

I don't know their circumstances or how many have had this problem. I don't know if the R plugs would help or not, but I would think that the R plug would not make any difference.

[Dale S.]

Re: C2:67 Spark Plugs - AC 44

Jerry, I use the 45S in my C-2 327/300 for chugging around town. Dale

[John H.]

Re: C2:67 Spark Plugs-What's the difference

Jerry -

If you MUST use the LL wires, resistance-check each repro wire BEFORE you install them to make sure they're not open, and handle them VERY gently while installing; LL must have changed their source of bulk spool wire in the last two years, as their wires have really gone downhill recently. Next time I need wires, they'll be Delco replacements.

I run AC R45S plugs in all my small-blocks (and have for years), including my 11:1 domed-piston Z/28, and have had no problems with any of them (and no more fouling).

[Mike McKown]

Re: C2:67 Spark Plugs - AC 44

I'd agree with this and add that cutting the stock deck height would have something to do with it also.

Never seen this in real life, just in print.

[Scott S.]

Re: C2:67 Plug wires

How about Kanter Auto in Boonton NJ? He bought the Packard car rights years ago and lists Packard wires also. Anyone ever use him?

[Gerard F.]

Re: C2:67 Spark Plugs-What's the difference

John,

Are the plug wires supposed to have a certain resistance per length, or just continuity?

Jerry