Urgent - Spark Plug Question

[Michael A.]

It's Saturday night and I'm in the middle of replacing the spark plugs on my 66 327/300. I am pulling the old AC44s out and replacing with Champion RJ14YC. I chose the Champion RJ14YC (an AC45 equivalent) based on a recommendation from John Hinckley in a 2002 post on the Archives (you gotta love them Archives). John's experience is that the RJ14YC are less prone to fouling.

Here's the question, the RJ14YC is about .15" (a little more than an 1/8") longer from the washer to the tip than the AC44s I am replacing. Is there a chance they could hit the pistons?

I know the original owner had the engine rebuilt in 1990. I know nothing about the rebuild other than he had a bit more of a performance cam put in it. Other than that I don't know if it would have had domed pistons installed. Any suggestions on what I should do? I'd sure appreciate the input.

Thanks

[John F.]

Re: Urgent - Spark Plug Question

I don't think you would have a problem. To check, put one in and rotate the crank manually to see if it hits.

[Joe L.]

Re: Urgent - Spark Plug Question

It's Saturday night and I'm in the middle of replacing the spark plugs on my 66 327/300. I am pulling the old AC44s out and replacing with Champion RJ14YC. I chose the Champion RJ14YC (an AC45 equivalent) based on a recommendation from John Hinckley in a 2002 post on the Archives (you gotta love them Archives). John's experience is that the RJ14YC are less prone to fouling.

Here's the question, the RJ14YC is about .15" (a little more than an 1/8") longer from the washer to the tip than the AC44s I am replacing. Is there a chance they could hit the pistons?

I know the original owner had the engine rebuilt in 1990. I know nothing about the rebuild other than he had a bit more of a performance cam put in it. Other than that I don't know if it would have had domed pistons installed. Any suggestions on what I should do? I'd sure appreciate the input.

Thanks

Mike-----


I have used Champion RJ14YC plugs in my 1969 300/350. That engine has the same combustion chamber configuration and same piston top configuration as a STOCK 1966 300/327. I had no problems, whatsoever, with the RJ14YC.

Of course, if the engine has been significantly modified from stock with the use of domed pistons or seriously milled heads or block, that MIGHT change things. I doubt it very much but it's possible. By the way, I also know that the RJ14YC will work fine with a 1969 L-46 which has domed pistons.

[Clem Z.]

Re: Urgent - Spark Plug Question

index the ground electrode to a position between 8:00 o'clock and 4:00 o'clock and you will have no problem

[Michael A.]

Re: Urgent - Spark Plug Question

Thanks everyone. I turned the engine over and checked a sparkplug. No contact. I've since completed the install and taken it for a short ride. It's amazing what a difference a tune up makes on a car that is in need

Cheers,

[Clem Z.]

Re: Urgent - Spark Plug Question

the only time i ever saw a piston hit a extended reach ground electrode was when it was at 6:00 o'clock position but it can happen. this was a 1961 SHP corvette.

[Wayne D.]

Re: Urgent - Spark Plug Question

index the ground electrode to a position between 8:00 o'clock and 4:00 o'clock and you will have no problem

Clem, Could you tell me how to index the electrode? Thanks, Wayne

[Clem Z.]

Re: Urgent - Spark Plug Question

mark on the insulator with a magic marker,DO NOT use a lead pencil, the location of the ground electrode. install the plug in the head and if you can see the magic marker mark looking down from the top you are OK as the ground electrode is not at the 6:00 o'clock position. you may have to try the plug in a different cylinder if does end up at the 6:00 o'clock position

[Dale S.]

Re: Urgent - Spark Plug Question

We sold hundreds of thousands of spark plugs over the years (30++). Never had a problem with piston to spark plug contact, except when an engine was modified by someone who did not know what they were doing. Dale