Spark plug gap size

[vso737]

Hi,


I know the stock gap calls for a setting of .035"........................

I'm installing new platinum spark plugs, Autolite AP85. I have a 1969 RR 383 CI MOPAR with an MSD unit.

¿ What should the spark plug gap be set at ??

Thanks a bunch,
LG,
Mike:acne:

 

[Big John]

The MSD will like a bigger gap. I used to run .055 gap and that was recommended by the tech at MSD.

 

[quikbird]

I have an msd and that is what mine are set up to. As always listen to big john. :yesnod:

 

[vso737]

Thanks again BIG JOHN...............

FYI- Right after I posted the request. I checked the internet and came across the following info for MSD units.

"spark plug gap for compression up to 10.5:1, should be .050 to .060; 10.5 to 13, should be .040 to .050; and compression motors above 13:1, should be .035 to .045."

So it appears that John was right on the money at .055. Right in between the .050 to .060 recommended in the above stated article.

I decided to check my Autolite 85 plugs. I ONLY checked the left bank four plugs. I was shocked to find that ONLY one was even gaped at the original stock gap of .035. The other ones were in the .020 to .025 range.

FUNNY thing is that the car starts up extremely easy and runs great. The entire motor has less than 5,000 miles on it. The ONLY reason I'm replacing plugs is because I have them out due to having to remove the headers to get them ceramic coated.

I will be replacing the plugs with Autolite AP85 which are platinum plugs and from what I understand a much better spark plug.

I will gap them at .050 since I have a way of being sloppy..............I expect them to eventually end up in the .055 range after I'm finished.

ONCE again, thanks a bunch for the quick response,
LG,
Mike