Plug Gap on 351C motor

[automart]

I have a 70 351 C and put the MSD dist. in. The plugs are AP 25 (Autolite) the first set seem to file out pretty fast, I have only started it in the garage. The motor is new.

I'm just trying to figure this out.

 

[68torinogt]

im thinkin 35 thousandths its a good general start

 

[automart]

I think the newer plugs are pre-gapped for the electronic ignitions, since the MSD is electronic, I did not change the gap. Isn't the gap larger than the old style points/condensor distributors? I remember the gap was around .32-.35

 

[68torinogt]

not nececarally i gap them on newer cars at .32 all the time b/c that is what it calls for. i would call the local parts store and ask they will give you what is needed for it. but i think on the older cars its .35 or so also

 

[67&05STANGS]

Automart,
Did you also put in a high voltage coil? If so, you can gap the plugs higher. I have the Pertronix setup with their Billet distributer, Flame thrower coil (40,000 volt) and wires. I have my plugs gapped at.45 and the car runs great and the plugs are clean.

 

[automart]

I'm not sure about the coil. I forgot what kind it is, my son bought it for his 95 GT but didn't use it. It is the same size as the factory.

Did I mention I hate to pull the plugs on a Cleveland, It's a pretty tight fit. It looks like the new plugs are around .60, The new ones I pulled out were all black.

 

[dodgestang]

I run the plugs in my cleveland at 45 with a MSD box, dizzy and blaster 3 coil.

 

[bnickel]

i have a mallory unilite with stock coil and the plugs are gapped at .035. with a hoter coil like an msd blaster i would open the gap up to .045.

 

[truck90278]

With an electronic ignition, run a larger gap ~.045. If your plugs a black, then you may be running rich, they should be closer to gray

 

[66HertzClone]

Did I mention I hate to pull the plugs on a Cleveland, It's a pretty tight fit. It looks like the new plugs are around .60, The new ones I pulled out were all black.

A trick I was taught in high school was using a short piece of rubber fuel hose stuck over the porcelain end of the plug when installing new ones. I sure makes it easy to feel if the threads are engaging correctly, and the plug won't fall out like it will if using a socket.