I pull out my distributor and welded the shaft ,had a little play. I had some rust in there and sprayed some on pb blaster on it. I put it back in and set the timing. Went to test it and the car ran bad. Went from 6.55 to 7.10. From 103 mph to 90. Would the PBS blaster cause this issue.

Welded the shaft??????

No ,tacked the top were the springs used to be. It was locked but had just a little play.

The reason you have rust forming in the distributor is because it does not have enough ventilation. That little black cap at the top of the distributor cap is the air vent and does not provide enough ventilation especially if you are in a humid climate.

I suggest placing at least two 1/4" dia holes 180* apart in the cap 1-7/8” up from the bottom of the cap between the spark plug towers. I have put in four holes with good results also, but try starting with two.

Try using some Electrical Contact Cleaner spray to clean out the interior to include the reluctor and pickup.

One last thought. If you welded it when it was still in the distributor you may have damaged the pick-up. A MSD Billet distributor pick-up should measure 500 - 700 ohms with a meter.

It was still in the distributor, I will ohm it out. Thanks

I just check it and it ohms at 738 . I'm assuming since it out of the 500 to 700 it's bad?

I went out and metered the MSD distributor pick-up in my car. Measured at 516 ohms. My bet is that it’ll possibly measure higher when heated up.

Try replacing the Magnetic Pickup Assembly, MSD 84661. Not hard to do.

I had another msd distributor and it was 518. Then I checked the one in the car and it was cold and it was 738.

This might sound silly, but did you re-check the timing after you welded it? I’m assuming you welded it solid to avoid the mechanical advance?

I pulled the distributor out welding it and put it back in and set the timing on 36 degrees.

I've had quite a few issues with MSD pick up's through the years. Seems they all have been completely different problems. I always carry a spare cause every year or two it's going to fail.