Spark Plugs - 68-L79

[Richard D.]

What plugs would you recommend for the above motor?

The stock ones were AC-44's per my book, and it now has AC-43's in it for some reason or another.

What's the difference between the 2 codes? The car seems to run real well with the 43's in it.

Thanks in advance for any advise,

Rich

[Jim T.]

Re: Spark Plugs - 68-L79

You may not believe this, but checking my maint log for my 68 L79 to see when I last installed sparkplugs. About 15 years ago installed J12YC Champions and the car runs great and starts immediately.

[Jim T.]

Re: Spark Plugs - 68-L79

You may not believe this, but checking my maint log for my 68 L79 to see when I last installed sparkplugs. About 15 years ago installed J12YC Champions and the car runs great and starts immediately.

[Jeffrey S.]

Re: Spark Plugs - 68-L79

Rich:
The difference between a 43 and a 44 is the heat range. The second number in the designation is the heat range or, in other words, how long the plug retains heat (the first number is the thread size-in this case 14 mm). The higher the number the longer heat is retained. The numbers range from 1 to 9. A hotter plug will resist fouling better than a colder plug. The down side is that a plug too hot for the engine will "ping". Your car came with an AC44 plug. A good choice for light duty use would be a 5 heat range. I'm surprised that a 3 heat range didn't foul in your car. Most cars that call for a 4 and are used for "cruising" or ice-cream getting do much better with a hotter plug. Hope this helps.
Jeff

[Jeffrey S.]

Re: Spark Plugs - 68-L79

Rich:
The difference between a 43 and a 44 is the heat range. The second number in the designation is the heat range or, in other words, how long the plug retains heat (the first number is the thread size-in this case 14 mm). The higher the number the longer heat is retained. The numbers range from 1 to 9. A hotter plug will resist fouling better than a colder plug. The down side is that a plug too hot for the engine will "ping". Your car came with an AC44 plug. A good choice for light duty use would be a 5 heat range. I'm surprised that a 3 heat range didn't foul in your car. Most cars that call for a 4 and are used for "cruising" or ice-cream getting do much better with a hotter plug. Hope this helps.
Jeff

[Richard D.]

Re: Spark Plugs - 68-L79

Jeff, thanks a lot for the info.

The fellow at the parts store also said there was some difference in the length of how far it extends into the head.

I drive my car about once or twice a week on weekends, and don't beat it too hard. I do open it up to blow the crap out of it occasionally, but otherwise just tool about in it, as you described.

Would there be a performance difference in using an "R" or resistor type plug, like an AC-45R? I'm pretty sure that's what the fellow said he had in stock.

From what I understand, the R means it's a "Resistor" plug, primarily for Radio interference suppresion.

I will be installing a radio shortly, but the car currently does not have the stock distributor shielding in place. I hope to get to that in the not too distant future.

Will R type plugs make any difference?

Thanks again for the info.,

Rich

[Richard D.]

Re: Spark Plugs - 68-L79

Jeff, thanks a lot for the info.

The fellow at the parts store also said there was some difference in the length of how far it extends into the head.

I drive my car about once or twice a week on weekends, and don't beat it too hard. I do open it up to blow the crap out of it occasionally, but otherwise just tool about in it, as you described.

Would there be a performance difference in using an "R" or resistor type plug, like an AC-45R? I'm pretty sure that's what the fellow said he had in stock.

From what I understand, the R means it's a "Resistor" plug, primarily for Radio interference suppresion.

I will be installing a radio shortly, but the car currently does not have the stock distributor shielding in place. I hope to get to that in the not too distant future.

Will R type plugs make any difference?

Thanks again for the info.,

Rich

[Craig S.]

Re: Spark Plugs - 68-L79

Resistor plugs will work just fine.....except for judging.......Craig

[Craig S.]

Re: Spark Plugs - 68-L79

Resistor plugs will work just fine.....except for judging.......Craig

[Jeffrey S.]

Re: Spark Plugs - 68-L79

Rich:
The AC45 and ACR45 are identical in performance and configuration. The "R" prefix stands for "resistor" and it was to help suppress radio noise. The ACR44 was a replacement plug until 1969 when it began to be put in at the engine plant. Your patrs man is incorrect if he says that the reach of the R45 is longer than the 45. The designation R45 or 45 without a suffix letter means that it is a 3/8 inch reach. They are identical. He probably has an R45S in stock that has an extended tip (elecrode). This would also work just fine in your car assuming that you have stock heads and pistons. Hope this helps.
Jeff

[Jeffrey S.]

Re: Spark Plugs - 68-L79

Rich:
The AC45 and ACR45 are identical in performance and configuration. The "R" prefix stands for "resistor" and it was to help suppress radio noise. The ACR44 was a replacement plug until 1969 when it began to be put in at the engine plant. Your patrs man is incorrect if he says that the reach of the R45 is longer than the 45. The designation R45 or 45 without a suffix letter means that it is a 3/8 inch reach. They are identical. He probably has an R45S in stock that has an extended tip (elecrode). This would also work just fine in your car assuming that you have stock heads and pistons. Hope this helps.
Jeff