Tark's plugs

["Jeff Tarquinio" <tark_terra@domain.elided>]

John H said:
"Tark,
In my opinion, I wouldn't think that the two resistors would cause the problem you were having.  I also don't think that having the two resistors would affect your dwell in any way. It seems to me that a carbon buildup like you describe has to come from running way too rich, which could be exacerbated by poor ignition,"

The reason I mentioned dwell is that the time of dwell shortens at higher rpm, less time to charge the secondary.  My problems arose after 2500ish.  My point was that with too much ballast resistance, both ACCEL and oem R-wire inline, I was seeing maybe 3-4 volts at the coil.  Low voltage + short dwell time = weak spark.  Maybe weak spark caused the fuel not to completely burn, as if rich mixture was an issue.  Carbon build up on the plugs, they bridge, overheat from too much current, weakens/ruins the electrodes.

"but I don't think the two resistors caused your ignition problem if it was ignition that caused the too-rich running."

Maybe not, but it makes sense to me. Is there no validity to my theory?

"Wait a minute!  Your 345 is a 77? correct. It has a Holley dist. and a gold box? Right?"

Sorry John, I have a very confusing bunch of rigs.  The '77 Terra is pure '77, gold box blah blah. Of course that one runs perfect, but its sort of out of comission in mid project.  The '80 originally had a Deisel/T19/D300 that smoked, I helped the PO swapped out that drive train with the '74 345/727/sptc.  This is the rig thats giving me trouble, holley points ign, holley 2210, .......
We won't even get into whats left of my '77 traveler!

"That system grounds out the coil thereby activating the change in the coil's magnetic field and causing the spark. So, the resistors are only involved in the amount of current flowing to the positive side of the coil and have no effect on the Gold box. So does your
Terra even have a ballast resistor? As I remember, you don't need a ballast resistor with the Gold Box."

Right, no ballast on the '77, I kept it though, and used it to replace the one I burnt up the other day on the 304.

"When it is used, the ballast resistor is mainly on the coil to keep the points from suffering from too much current flow when they complete the ground circuit so that the coil fires.  However, as I recall, the MSD ignition and the Pertronix both use the ballast resistor even though they don't use any points. Actually, I know the MSD requires the ballast as that is what I have on my Terra, and as I posted earlier, I think Darrel told us that it is needed on the Pertronix.
John Hofstetter"

I read on some FAQ I found on the net that you should see about 8-10 volts at the (+) coil.  Last night, I was working on the 304, I had 7 volts at the coil with just the ACCEL resistor in line.  I measured the resitance of the Primary of the coil at about 1 ohm and about .7 ohm on the Resistor.  12v * 1 ohm/1+.7 ohm ~ 7 volts to the coil.  That seems about right to me.

Thanks for the advice John!  I think I'm getting there little by little.  I appreciate your thoughts.
---
Layda,
Tark
'77 Terra 345/T19/D20
   Survivor of '98 Scout Nationals
'80 Scout II 345/TF727/single speed tc
   Clean machine




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