cap and rotor question

NecroWolf

NecroWolf

lost marbles member
so i started my truck after i got it idling right and as is the nature of my beast it started idling rough with a slight miss. went out to start it again and it wouldn't start. i tracked it down to my pass through for my coil, it was arcing to the sheet metal around the pass through, a nice one inch spark. so i putzed with it ohmed out the pass through, it was good switched cpo; wires around, tried insulating the sheet metal, etc etc. finally pulled my cap and rotor and the center terminal on my cap ohmed out at around 140ish, the spring was toast and there was scorch marks on the rotor. i have seen them like that at like 60k miles but i think i have maybe 5-10 hours on it idling. now i need a suggestion on a better cap and rotor, i was thinking msd, or my spark was just too hot. i have a 6al with the mad gm type coil, the cap was the common one everyone uses purchased through this board new. anyone have any input or suggestions?
 
SY2455

SY2455

70's Veteran
Re: cap and rotor question

NecroWolf said:
so i started my truck after i got it idling right and as is the nature of my beast it started idling rough with a slight miss. went out to start it again and it wouldn't start. i tracked it down to my pass through for my coil, it was arcing to the sheet metal around the pass through, a nice one inch spark. so i putzed with it ohmed out the pass through, it was good switched cpo; wires around, tried insulating the sheet metal, etc etc. finally pulled my cap and rotor and the center terminal on my cap ohmed out at around 140ish, the spring was toast and there was scorch marks on the rotor. i have seen them like that at like 60k miles but i think i have maybe 5-10 hours on it idling. now i need a suggestion on a better cap and rotor, i was thinking msd, or my spark was just too hot. i have a 6al with the mad gm type coil, the cap was the common one everyone uses purchased through this board new. anyone have any input or suggestions?
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I was going to answer this morning but ran out of time before work. I had the MSD-6A with the MSD coil and MSD plug wires with a brand new Conard Cap and Rotor. In 1 month time the spark was so hot that it burned 6 holes in the cap just below the spark plug terminals. So now I use the MSD 6A with a stock coil and MSD plug wires with NGK Iridium plug # UR6IX 7348 and haven't had any problems for 3 years.
 
cloneman315

cloneman315

Active member
Re: cap and rotor question

i have had a msd digitial 6. 5 year old magnacore wires with headers,and replace my cap once a year and I have had great luck,its a msd cap and rotor,but i also dont daily drive my sy either
 
NecroWolf

NecroWolf

lost marbles member
Re: cap and rotor question

i'm thinking i'm going msd cap and rotor unless i can find better, if that doesn't work i'll go back to the stock coil. i just don't want to give up this good of a spark if i can
 
cloneman315

cloneman315

Active member
Re: cap and rotor question

lot of guys say msd stuff sux,this is crap ,they either have other problems and the msd makes it worse or they have a bad part,msd stuff works!!
 
SY2455

SY2455

70's Veteran
Re: cap and rotor question

cloneman315 said:
lot of guys say msd stuff sux,this is crap ,they either have other problems and the msd makes it worse or they have a bad part,msd stuff works!!
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I do agree with you here that MSD stuff works. I really like it and will keep running it. To be fair at the time that I had the problem with the cap, I was using the truck as a DD and couldn't be without it, so I just got a new cap and rotor with the stock coil. Maybe I will try and find the reason for the very hot spark burning holes in the cap. The only part that I need to change is the coil as all the other MSD stuff is still on the truck and working great. Maybe it is just a matter of finding a cap and rotor that will stand up to the hotter spark.
 
NecroWolf

NecroWolf

lost marbles member
Re: cap and rotor question

SY2455 said:
That why I installed it when I first got the truck . I gained gas mileage too.:tup: On the HWY with cruise on at 70mph I get 25mpg.:tup:
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that is awesome, i'm running all msd except cap and rotor, so i ordered them tonite. i figure that cap was just not up to it. i'm starting to get an idea why these trucks eat ignition parts. the recomended cap and rotor are weak, i'm starting to think the ngk plugs are that keen under boost but the tailor wires are excellent. i went through two caps/rotors and three sets of ngk plugs and never changed wires once i switched from accel wires to taylor wires. i am thinking i'm going to start experimenting with different plugs now.
 
kentuc

kentuc

Member
Re: cap and rotor question

What gap are you running?
The spark is going through the path of least resistance,
A smaller gap might work better.
 
SY2455

SY2455

70's Veteran
Re: cap and rotor question

I set my gap at .028 on the Iridium plugs listed above. and they have been in there for 3+ years working the same as day 1.
 
NecroWolf

NecroWolf

lost marbles member
Re: cap and rotor question

kentuc said:
What gap are you running?
The spark is going through the path of least resistance,
A smaller gap might work better.
Click to expand...

.30 but like i mentioned my cap ohmed out real bad, so i think that fancy cap was just a little weak. i forgot to mention the spring lost all tension too
 
Don W.

Don W.

Stab it and steer it
Re: cap and rotor question

I bought a MSD coil and it was bad. You could actually see that it wasn't assembled correctly. It was replaced at no charge and, along with the 6al, has done well. I didn't notice much difference in the idle though. MSD also recommends venting the cap with a couple of holes drilled through the side.
 
NecroWolf

NecroWolf

lost marbles member
Re: cap and rotor question

Don W. said:
I bought a MSD coil and it was bad. You could actually see that it wasn't assembled correctly. It was replaced at no charge and, along with the 6al, has done well. I didn't notice much difference in the idle though. MSD also recommends venting the cap with a couple of holes drilled through the side.
Click to expand...

i don't have a problem doing that
 
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