crane xr700 red coil blue coil very old tk12a10 coil ballast

[Scutch]

I installed the Crane xr700 ignition a couple weeks back and everything is fine, but I think I should replace the coil.

After installing the xr700, the last very hot day we had here in Colorado I drove to the airport and turned the car off and then it would not start until I let it sit for 15 mins. That has happened before in heat. I read that a worn coil can do that in heat. So I got a multimeter and tried to test it. I think the first stage test was fine, if I remember maybe just under 1 ohm. But the 2nd stage was inconclusive, way up in the tens of thousands.

So when I look up a coil on parts places for my car it says I need the Bosch Red coil 00013. The coil in there now only says "tk12a10" at the bottom. When I look that up, there is not much info. Maybe I am seeing in posts that it could be the original coil? (More reason to replace it me thinks.) But don't know if a tk12a10 was a red, blue or black coil originally.

The xr700 directions say to keep the ballast resistor in, but I was wondering if that was the case also for a Red Coil. I thought those were not really stock coils, just the blue and black ones were for w111s.

Any opinion on if it makes sense to put a Red coil 00013 in there and leave the ballast resistor with the xr700?

The car starts fine cold, but seems to sputter and miss a lot when I accelerate unless I really let it warm up. I don't remember it doing that so bad last cold season when I still had points, but not sure. Maybe the xr700 may not be so great accelerating in the cold? Just trying to get the best spark I can and see what it can solve.

I did also gap my NKG BP6ES plugs down to about .027, down from .033.
I also advanced the timing up to 10-12 degrees BTDC, but it felt better back at 7. It sputtered worse in the cold with the timing more advanced.

[Frank Reiner]

S:

The coil that you use, irrespective of cosmetics, and the external resistance (aka, ballast), should have a combined resistance of between 3 & 4 ohms in the primary circuit. If the internal resistance of the coil is in the range, then no external resistance is needed.
One such coil is Bosch 0 221 119 309 (3 ohms). If one is feeling very conservative, an external resistor of .4 ohms could be added.