Merry Christmas All!
I have an 88 F250 w/ 5.8L that I have been fine tuning for a month or so now. It's running pretty good now until I get on the gas, it then misses and occasionally a muffled backfire. I replaced plugs, wires with Motorcraft brand. I replaced the cap and the bottom part of the cap with Duralast from Autozone. When you grab the cap it does not seem very tight, it seems awfully wobbly sitting on there. Is this normal for a Ford distributor cap? 2 screws hold the base down and then 2 spring steel clips hold the cap on it. A little voice in my head tells me to get a new cap and bottom from Motocraft.

 

No, I have never seen a "loose" cap, EVER on any brand

 

x2 ... no slop allowed.

 

That's what I kinda thought, I'll be taking a trip to Autozone tomorrow.
Thanks!

 

I had that on two different dist. caps. When I got the truck it had that slop and the new cap I got has slop in it. Not a whole lot but enough to make you go "Hmm, don't think that's right".
If you get a cap and it fits tight....let me know what brand it is please. Thank you and good luck!

 

Well, I showed this to my local Autozone guy and he agreed, it should not be this loose. He said I could buy a new one and bring the old cap back for a refund after I swap them out. The upgraded "gold" Duralast cap was $30. He also informed me that the whole distributor with cap (gold), rotor, module, base cap, gears and all was only $99. So I bought the whole setup. Haven't installed it yet but I can say that the cap on it is not wobbly or moving around at all.
Keep your fingers crossed and I will let you know how it works out.

 

Well, I'm just about aggravated as I can be. Put in the distributor and it ran worse. Changed back to the old one still ran like crap. All I could figure is that I got the distributor in the wrong position so I cranked it around by hand to TDC when the rotor should be pointing at #1 spot in the cap (it was at 11:30 position but should be closer to 1:00). I could not get the rotor on the old distributor to point directly at #1 (or 1:00) so I tried fitting the new distributor and it lined up perfectly, I thought that I may have it now, tried to start it up and would hardly run. In order to then get to 10 degrees btdc I had to twist the distributor pretty far. Now the module is pointing straight forward and running like it did before installing the new distributor.
Btw, the new cap does wobble around just like the old one. I guess I wasted an entire afternoon for nothing.

 

Crap parts is most of the time. Ive had good luck with MSD caps, and standard caps. You always have to mark the dizzy and position of the rotor installed, and where it stops when you pull it out and try to transfer to the new dizzy.