Plug gap

[furyus 67]

Hey gurus and car guys! I am currently running champion rj12yc gapped at .035, it seems to work well. Just wondering if I am on the right track or if there is a better plug/gap combo. I've got a 1972 413 with a stock rotating assembly, 284/484 Mopar performance purple cam, 906 heads , a weiand intake,edlebrock 650 carb and a digital MSD 6al. Any input will be appreciated!

 

[Badvert65]

I swear by Autolite 86 gapped at 0.040 for the street and 0.045 for the track.

 

[68plymouth383]

I use the rj12 gapped at .035. Every autolite I've used has been worse than the champion plugs

 

[furyus 67]

I'm thinking(and please correct me if I'm wrong) because I have a fairly low compression ratio(7.5-1/8-1 I think) it's not going to be very picky. The champions worked well until they fouled out do to my carb not being adjusted.

 

[twostick]

What coil?

Stock coil I'd do no more than .045".

If you are running a good coil like an MSD Blaster or better, I'd try at least .060". On a fairly stock low compression engine, the bigger the spark the better the flame front which can equal better fuel economy and power (not necessarily at the same time).

Kevin

 

[furyus 67]

MSD blaster 2. Thanks Kevin I'll give it a try. I was running .035 for the initial fire up and seemed to work. It was a edumacted guess tho.

 

[Big_John]

With the MSD you can widen the gaps out to .050-.060. I used to do .055 with a stock coil and my MSD6 in my A12. I called MSD a bunch of years ago and they recommended that gap. It worked well for me.

 

[furyus 67]

Thanks John!