Can I swap my stock-style dizzy cap for an "HEI" one with the nipples?

THAT'S THE ONE!!!! $34, in stock.

And don't worry when you see that there is no notch cut out over that screw...this one has a thinned area (you can see it at 3:00 on that pic above) that squeezes in between the screw and the distributor.

 

I don't get it. My MSD cap was only like $23.00 (and it comes with the adaptor). Any Duraspark cap should fit. I thought you were looking for the kind that has the terminals coming out the sides (horrizontal) instead of the top (vertical)...

 

Nope, looking for the one like the picture above. It has to be small diameter but I want the snap on make tips.

I will take my car back to Napa tomorrow, and put a depth guage in that one and my stock cap and verify that it will work with the stock rotor. It appeared that it would. If it is the same depth, I will buy it and wait for new wires...

 

Bought It!!!

The depth of the stock cap is 1.765, depth of new HEI-type cap is 1.695 for a difference of -.100. The spring-contact on the rotor has .25 movement, so it will have to compress an extra .100 with the new cap.

The distance from contact to contact on the stock cap is 1.925. Distance on the HEI cap is 2.890 for a difference of -.035. So the rotor will swing closer to the contacts by .0175".

The contacts of the stock cap are L-shaped, so apparently the electricity jumps not only across from the tip of the rotor, but also up from the top face of the rotor.

The contacts of the HEI-type cap are just a blade, so the electricity will be able to jump ONLY from the tip, therefore, the closer the tip to the contact, the better (I would guess).

Final test before firing it up. Installed new HEI-type cap and rotor, snapped it all down, loosened distribtor, and it rotates freely without hitting the rotor.

As soon as I get wires that will fit this, I will fire it up and confirm that it works :bananaman

 

It Works!!!

I went ahead and took my wires off the old dizzy, crimped them a bit so they would sorta snap onto the terminals, and fired her up :bananaman

I will put this part on the Parts Interchange forum.

 

I would like to add to the discussion.
I have never saw a blade type cap and wonder who made it!. A flat terminal does not follow the rotor arc of travel.
There could be a problem with high speed miss if the rotor to plug wire terminals are to wide a gap. The spark has to jump this gap as well as the plug gap and deal with wire resistance to boot as well as plug center resistance. This drives up the voltage requirements from the coil until the reserve is reached, then miss fire can occurr.
A way to tell what is going on is take caps and drill a 5/8" hole at the base of #1 plug wire tower. Hook up a timing light and see what the gap is and how far the rotor moves with ignition advance.
The closer the rotor comes to the wire terminal the better.
In addition, for interest, the EFI dist works different than the old type in that the rotor to plug tower relationship never physically moves; only the spark timing from the computer changes in time as rotor passes by and only "appears" to move by strobe light since the EFI dist has no built-in centrifigal advance to move the rotor position..

 

GM HEI caps are that way.
Some HEI replacement caps have the solid posts we are used to, all depends on the maker.

 

I will be getting some HEI wires probably early next week. and will let you all know how it runs. May as well put in a new rotor, since the one I am running now has some wear on it...Just to get THAT out of the equation.