Failure #2 of MSD distributor cap on FE ???

[Tom Kirkham]

Those of you that are going through distributer caps and rotors way faster than normal need to check the rotor phasing to the cap.

[convincor]

This is why I prefer a stock distributor with a electronic conversion.
If something happens to the cap I can pick one up at any autoparts store.
Hate to be 75 miles from home and stuck on a Saturday afternoon and have to wait til monday to special order a replacement.. just my $.02

[Rick Parker]

My observations......

Several years ago when MSD brought out their "Small Diameter Pro Billet" distributors for the 289/302 I just had to have one. I was near the front of the line. Anyway... it originally used a black cap sourced from an Application from an International truck V8, and a Chevrolet style rotor. The cap had aluminum terminals which I wasn't crazy about. With a little research I found that Napa, KEM and a few others made a cap for that application with brass terminals which was interchangable. Fast forward a few years and MSD brings to market a replacment cap made from red ryonite (their red plastic, nicely done). BUT after checking some dimensions with a dial caliper, I realized the tip of the rotor was passing about .160 UNDER the brass terminals in their cap, it did not pass to the inside and next to the terminals as I expected they would. TO me this distance seemed excessive and would seem to create a lot of resistance. It was also appearant that the top blade on the rotor was not touching the button in the center at the top, again creating resistance and arcing. That along with the fact that the cap was a little taller but only available (at the time) in red sent me back to the earlier ones made by NAPA , KEM, etc.
Now (this month) MSD is releasing the original red only cap in black and has also brought out a rotor that has the ability of allowing the tip to be adjusted and improve the phasing of the rotor tip within the cap. So we will see if it works any better.


MSD Adjustable Race Rotor PN8421

MSD Cap Rotor Kits PN84335
Black Small Diameter Cap (cap only) PN 84313 (Top Cap)

These also fit 351 distributors using similar caps.

It's just a part that requires occasional replacement to keep a sharp edge on your ignition system.

[bobcowan]

Originally Posted by Tom Kirkham

Those of you that are going through distributer caps and rotors way faster than normal need to check the rotor phasing to the cap.

?????????

Could you explain that, please?

[scootter]

Duane,
I burned two up before I realized the rotor tab wasn't making good contact with the cap. I bent it up a bit, and have had this cap on for about 12k or more and still looks fine.
Scott

[patrickt]

Originally Posted by bobcowan

?????????

Could you explain that, please?

[diegokid]

I went through this a few years ago having the same problems. I bought a NAPA distributor cap with brass and the matching rotor. I even used a ohm meter to check the resistence between the two caps. The cheaper NAPA had less resistence and cost less.