For a mopar distributor? These unribbed ones dont work well at all.

I just bought another Accel 8320. Tan in color, brass terminals, they always serve me well.

is it ribbed?

Accels for me too. Never had an issue with them.
I believe they are ribbed, can't recall the last time I had one off !

I just threw some new, original caps away. I took them to the last swap meet and tried to sell them for a few bucks each but nobody was interested. One guy wanted to know if they were for a dual point distributor. I have no idea if dual points used a different cap, not sure why they would so I told him I didn't know.

The cap and rotor are different between the stock single point and stock dual point distributors, the dual point caps have the carbon from the coil wire going to the flat rotor. The single point caps have a brass pointed thingy( CRS proper name () and the rotors have a flexable thin blade that pushes up against the brass contact
As far as the Accel caps, the new ones, both types, are smooth inside now

Chrysler caps whether point or electronic also have a cut out notch in cap for phasing on the tab on the vacuum can. Prestolite dual points have a molded protrusion that fits into the cutout of the clamp bracket, besides the differences Cab mentioned.

NAPA ECH M020

Copper, not ribbed, vented, USA.

Forgive my ignorance, what is the rib, and why does it matter?

Ribs inside the cap to help prevent crossfire.



I've used them both ways. As long as the cap is vented and the rest of the secondary ignition is in good shape, there shouldn't be an issue if they aren't there.

Internal ridges between the terminals, it’s sometimes used to reduce flashover arcing from the rotor to a WRONG cylinder’s terminal. I’ve been using unribbed caps with a MSD for 16 years without a problem.

I'd taken them if I'd seen them.

X 2

NAPA is the only cap and rotor I buy.


Tim

caps with aluminum terminals are the least desirable but will work. most performance caps are brass. the only copper caps i've found are blue in color and although copper is the best people won't buy the caps because of their color. to my knowledge nobody makes a ribbed cap anymore. i'm not certain the ribs are a big deal but the newer caps do have the vent which i like.

Echlin ECH AL124 pic shows black cap with ribs and looks like aluminum terminals? while specs say brass but no vent. The ECH MO20 pic shows a tan cap, no ribs, and a vent with brass terminals which is listed in the specs.


Tim

The ribs also help in damp locations. Had an issue where rain water would fall on the back of the motor and the steam would get in to the cap and cross fire. Get the Accel 8320 you won't be sorry!

all the new 8320's i have don't have ribs anymore, but they do have a vent.

if one were to add a vent hole to a B/RB cap, how large a hole should be added, and where would be the best location for that hole ?
could the hole be added to the side of the cap ?

ECH MO20 is an excellent cap along with rotor ECH MO3000

Accell here with the brass terminals, HI-6 ignition burns up the aluminium terminal caps in short order.