I have use Pertronix on two different cars, and they have worked great,both Olds. I put one in my 71 BB and ran great for about two days. When I went to work, and started to go on the freeway, it started to miss and backfire bad, let up on the gas and it ran pertty good. Took it easy and got to work. Comming home started OK, and drove pertty good, till I started to get closer to home. I have to go up the hill a couple of miles, and under a load, it missed and backfire bad, almost did not get up the hill. I don't think it is gas, as it was running great before, and I don't think fuel would cause bad backfire? Any Ideas? Thanks

Which model or # Pertronix is it?

# 1181, the one with the ring

Is it the conversion kit to change over from points. If so I know of people having problems with them. Spend the money and get the one that sells for about $160.

I've heard the opposite, that the 1181 is the good one (the original) and that the 2nd version caused some problems. I have also heard that the latest versions of both are greatly improved. I have the older 1st design with the ring and have never had a problem.

If it is missing only under load, it could be vacuum related. Check your vacuum advance can for proper function. Also, Pertronix ring style set ups are sensitive to excessive distributor shaft end play. Measure the clearance between the ring and the module at both the widest (rotor pulled up) and narrowest (rotor pushed down) points and make sure both are within tolerances as spelled out in the Pertronix instructions. If the gap is too wide it would cause misfires and backfiring. I would think the gap would be the widest when you are accelerating (the distributor shaft gear will climb up the cam gear thus raising the shaft slightly).

I've also had similar problems with cracked porcelin on spark plugs, but I'd venture a much stronger guess the problem is with the gap between the ring and the module.

..what Rich said.
The older,"cheaper" unit is actually the better one.
Actually,for the $160,I woould just convert over to an HEI
It doesn't have to cost $160 to have the stock distributor converted to electronic.
I've had great luck with the Mallory uni-lite conversion.

That's surprising. I've never had any problem or heard of any problem with the #1181 (original design).

I don't know what the problem was, as I checked the clearances, and did have to shim the drive gear. Put the points back in and is back running.

I've installed MANY 1181s and only had ONE problem. I discovered it was an installation problem, not a problem with the unit. I did not shim it properly. The gear needs to be shimed until there is about .005-.008 clearance. Then, the ring needs to be shimmed for about .010-.020 clearance. The ring WILL wobble a tiny bit. If it is too close to the module, it may touch ocassionally. If the ring is not shimmed down enough, and if the gear is not shimmed enough, the clearance (between the ring and module) will open up enough (as the dist shaft moves up and down) and the magnets on the ring will not properly break the circuit in the module. If I were guessing, based on your description, I would check for proper shimming first. Otherwise, it is VERY POSSIBLE that you have a defective module. PerTronix has been fairly good about replacing them if you convince them that your installation was done properly. The oldest 1181 that I have on any of my engines is 13yrs (my 56 Vette with fuel injection).

Tom's right. You have to disassemble the distributor and shim out the up and down freeplay. It will have to shimmed under the drive gear and under the advance mechanism.

Aircraft grade AN stainless steel washers work great for this. Don't ask me where I got them from Mr. Billscamino!

DZ you get away with only .005 to .008 shaft end play in an alum body dist? I'm afraid to go any tighter than .015 in those. Maybe I'm too cautious. I feel safe down to .010 in a cast iron dist though.

Yep, I do. Perfect example is the dist in my 70 conv (you're familiar with it). Been in there since 98.

OK thanks. I guess I'm still not that brave. Yes I'm very familiar with the '70 conv. Wish it were mine.