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Plug Gap on 351C motor

  • Thread starter Thread starter automart
  • Start date Start date Oct 2, 2006

automart

Member
Jan 26, 2006
104
0
16
Nashville, TN
Oct 2, 2006
#1
  • Oct 2, 2006
  • #1
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

Hey guys, guess what--I have a bi-pass!!!
Mar 21, 2006
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0
53
Welcome my son, welcome to the machine
Oct 2, 2006
#2
  • Oct 2, 2006
  • #2
im thinkin 35 thousandths its a good general start
 

automart

Member
Jan 26, 2006
104
0
16
Nashville, TN
Oct 2, 2006
#3
  • Oct 2, 2006
  • #3
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

Hey guys, guess what--I have a bi-pass!!!
Mar 21, 2006
0
0
53
Welcome my son, welcome to the machine
Oct 2, 2006
#4
  • Oct 2, 2006
  • #4
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
 
6

67&05STANGS

Member
Apr 4, 2005
54
1
6
Dearborn Michigan
Oct 3, 2006
#5
  • Oct 3, 2006
  • #5
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

Member
Jan 26, 2006
104
0
16
Nashville, TN
Oct 3, 2006
#6
  • Oct 3, 2006
  • #6
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

Active Member
Dec 15, 2003
1,360
0
37
Cecil County, MD
Oct 4, 2006
#7
  • Oct 4, 2006
  • #7
I run the plugs in my cleveland at 45 with a MSD box, dizzy and blaster 3 coil.
 
B

bnickel

Founding Member
Aug 21, 2002
5,640
3
77
lubbock, texas
Oct 4, 2006
#8
  • Oct 4, 2006
  • #8
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.
 
T

truck90278

New Member
Jun 4, 2006
382
1
0
Redondo Beach, CA
Oct 4, 2006
#9
  • Oct 4, 2006
  • #9
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
 
6

66HertzClone

New Member
Aug 24, 2004
428
0
0
Central New Jersey
Oct 4, 2006
#10
  • Oct 4, 2006
  • #10
automart said:
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.
Click to expand...

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.
 
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