MSD Distributor cap question

[Tim65GT]

What's missing in this picture?

This is the inside of my MSD Distributor Cap. Is this normal? I thought there was supposed to be a round end carbon contact in the middle that conducts the energy to the rotor. I didn't see anything fall out a couple days ago when I removed it to pull the distributor.

I had vacuum leak problems from bad intake gaskets, but the Ignition seemed to be fine. Anyone have any thoughts? Do I need to buy a new cap?

 

[tx65coupe]

I can't believe that part of it fell off, but it doesn't look right to me either.

 

[Tanus]

there is a beebee looking thing that should be there, I have a brand new msd cap sitting right here

 

[Tim65GT]

Thanks for the replys

I bought a new cap. ($33 + tax) They had one left in stock at the local speed shop. The missing item is called a carbon button and on some caps it is replaceable. Apparently you are suppossed to check to make sure there is no gap between the rotor and the carbon button. There is no mention of this in the installation instructions.

Any gap will cause the energy to jump and cause heat buildup and errode away the carbon button.

 

[tx65coupe]

I have never heard of that one before. I don't see how its possible to even check that with the cap installed.

 

[Tim65GT]

This is a response from an MSD tech for a poster who had a similar issue with fast wearing carbon ball:

Assuming that the carbon button was not damaged in transit, the only thing that I can see that would cause the carbon bushing to prematurely wear would be if the rotor tab was not making firm contact with it. If the energy was arcing from the bushing to the tab this will cause the carbon to wear away quickly. Upon installation of a new rotor (in any installation) we do recommend verifying that the tab is making firm contact. One way to do this is to apply a small dab of dielectric grease to the tab, set the cap on as if it was installed, remove the cap and look at the impression in the grease. You should have an indention down to the metal, if not you may need to bend the tab up slightly in order to get the proper tension on the tab.

 

[dennis112]

Thanks for the replys

I bought a new cap. ($33 + tax) They had one left in stock at the local speed shop.

FYI, a stock Ford Duraspark cap fits the MSD just fine. I swapped mine out because the Red MSD cap clashed with my engine compartment colors.