Small to large Duraspark cap adapter

[Pentroof]

Did I buy the wrong part? I'd like to move to the larger radius as well as the male terminals. I bought this kit from Summit. https://www.summitracing.com/parts/dui-32100bl

The adapter has a tab on the inner radius that does not correlate to a gap in my distributor base. Ironically, there is a gap exactly that width to the left of this location where the grommet for the wires is located. My distributor is not a genuine FoMoCo, it's an aftermarket purchased from Faron.

Think I'm OK to grind off that nub and just locate using the external vac canister mount like a traditional dizzy cap?

[Pentroof]

Incidentally, here's something you don't find every day...

[Cyclone03]

I think that indexes in the wire grommet groove .
Make sure it indexes properly to maintain correct rotor phasing.

[Cyclone03]

Interesting how the Summit image shows the notch for the vacuum advance screw.

 

[Pentroof]

I think that indexes in the wire grommet groove .
Make sure it indexes properly to maintain correct rotor phasing.

You think, or you know? I would like to know if that is the case, because mine will not.
Rotor phasing is a completely different topic. Wherever the cap locates, has nothing to do with rotor phasing.

[Pentroof]

Interesting how the Summit image shows the notch for the vacuum advance screw.

Why is that interesting?

[Cyclone03]

because yours does not

[Cyclone03]

I think that indexes in the wire grommet groove .
Make sure it indexes properly to maintain correct rotor phasing.

You think, or you know? I would like to know if that is the case, because mine will not.
Rotor phasing is a completely different topic. Wherever the cap locates, has nothing to do with rotor phasing.

well you have both parts line them up and check.
I have a very old blue adapter cap,uses the vacuum advance screw.
Moving the cap without moving the rotor absolutely effects phasing.

Hope you can work it out to your satisfaction

[Pentroof]

because yours does not

Sure does. Maybe I should have posted a larger picture. It's directly to the right of the big red arrow in the picture.

On the wire grommet location...no, I think you misunderstood. I'm now wondering if the wire grommet location on my distributor itself is different than a FoMoCo unit because this cap doesn't line up. I have two caps, yes, but small caps don't align on anything other than the vac advance. I don't have two distributors. The one in my other FE is a Mallory. If I line up the notch (that is there) for the vac advance screw, the metal clip also lines up. The tab on the inside doesn't line up with the wire grommet relief. I can't compare the small cap, because it doesn't locate there. So, if I assume this large cap is supposed to locate on the wire grommet relief and it is correct dimensionally, my imported distributor must be wrong.

So I still have the same question: Can someone with a cap adapter verify that this tab is supposed to be there and that it does locate on the wire grommet relief in the distributor? Or verify this adapter is for a different distributor?

[TomP]

That looks right and the tab goes where the tab on the small cap does. Rotor fits on like the stick one and cap clips on the adapter. All those are common parts off any 77 to mid 90's V8 Fords.

[afret]

Adapter:



Got rid of the vacuum advance unit so using a nut for the indexing instead:

[Pentroof]

Thanks afret. I see you don't have a place for the internal tab to locate either and it looks like you ground it of the adapter.

[TomP]

Hmm, yes. I just dug out a distributor and small and big cap with adapter. It has a notch in the side like Afret's that fits over the boss on the vacuum advance housing,
 Perhaps that cap adapter is for a TFI style distributor ? The standard late 70's 302 adapter is what you need. Regular auto parts store stuff.