Since there have been a few threads lately about the old brown or black 2 piece Mallory caps and buying them at swap meets, I thought I'd share a little info to help make sure you get the correct rotor for the cap. Yes, there is a difference. Somewhere along the line Mallory made a change to the contacts on the inside of the cap. Initially they were simply flat on the bottom of the contact. Then they made them with a notch. This change required that the contact strip on the rotor be shortened. If you put an "old" long rotor under a "newer" cap, it will hit. I'll show you the difference in rotors in the pictures. From what I can tell, all the brown caps are the older flat type contact. The 8 cylinder caps have the part number 24004 cast into the inside. Sometime after the switch to the black plastic cap, they changed the contact design. When they made this change, they also changed the part number in the cap to be 4004. They simply ground off the 2 on the old design's number, which can easily be seen on most caps. Of the approximately dozen black caps that I have owned, I only have 1 black cap that is the older 24004 style. Now, when I say that the newer cap has a 4004 number, that is NOT the number that the cap is marketed/sold under. That is simply the part number of the LOWER section of the cap. The whole 2 piece unit is actually 4001. I do not know the part number for the "older" variety, maybe 24001? Now the rotors. I am aware of 3 different versions. The longer one used with the 24004 flat contact cap, and 2 other short variations that are interchangeable and used with the 4004 cap. The longer version that goes with the flat contact 24004 cap has the number 24215B cast into it. The contact strip has a fat tip, and under the contact strip is a piece of spring steel that allows the strip to flex up and down on the rivet. The rotors I have seen like this have all been brown. The other 2 shorter versions used on the 4004 cap both have the 4215 cast into them, again showing signs of where the 2 and B of the earlier style were removed. One version has a fat tip, and the other has a narrow tip. None have the spring steel and are solidly riveted in place. All the fat tip ones I've seen are brown. I've seen both brown and black narrow tips. The actual part number on a package for the short rotor is 4215C. I'd assume the "older" long part number would be 24215 and a letter? In the pictures of the rotors, the left is the longer 24215B version. The other 2 are the short varieties. I've also shown a picture of the many different types of packaging the rotors where in over the years to help you spot them at swap meets. I couldn't get any good close up pictures to show the differences in the contacts, but in the brown cap photo, you can at least see where the number is located. Again, I've also shown a picture of 2 different boxes the caps came in. I hope this helps you get the correct cap and rotor for your Mallory. I'm not an expert in Mallory's by any means, just a guy who's got a fetish for them. Some guys like wheels, some gauges, some intakes. I like 2 piece Mallory's.
Great info for my Mallory collection of stuff. I have never seen the brown caps, only the black ones.
At least one of the NOS rotors I have has the spring steel under it & the rotor contact "floats" on this...I thought it was just an oddity - thanks!
The "floating" center rotor ( spring steel center) needs a cap with a fixed center carbon. The "solid" center rotor needs the cap to have a floating center carbon. One or the other has to float. Be careful not to mix the two! Good luck. Dave
Ever notice any difference in the underside locating notch for the rotor? Like Tommy recently found on an old two-piecer? Remember that Ducoil rotor I bought that might have fit my Mallory SuperMag? Different locating notch too.
I've never (as far as I know) had a locating notch on a 2-piecer like Tommy's. All I currently own are the standard type.
any idea where to pick up a new cap and rotor i picked up a Mallory DP for my 303 olds it's a type 250c
Can't remember what the numbers are on my mallory dual point, but the cap from Echlin at NAPA is an MA5 and rotor is an MA7. Thats if you want the one-piece cap. Some think they're lame i guess.
Dragging this post back up again because I just acquired an old Mallory YA11A with a 2 piece cap. It is in excellent condition, no binding plus the cap is very nice as well. Not sure why but the metal arm on the rotor is free floating. P/N on the cap is 24010X Where can I get cloth style wires that will work with this cap? Also I will be changing over to 12 volts, what will I need to do to the distributor for the change? Thanks
Any cloth wires that are the normal early size as used from creation until HEI days (is that 7MM??) will fit. You need no parts at the cap of course besides the actual wire. Look up Brillman tractor place online for everything you could possibly want in wire and Rajahs. (https://www.brillman.com/list/) If points and condenser are good, you are all done...they do not need changes. If cap needs replacement...it looks pretty good...you can use an 8 cylinder lower cap, which is somewhat easier to find. The old brown stuff is GREAT looking with a bit of polish, and the old iron 11 is a very classy piece. Mallory made its first Ford banger distributor in 1929! Yours is 2 or three generations of development in from those.
Thanks for the education once again Bruce. Have not looked it over real close yet but so far eally happy with it.
Still looking for an answer regarding the rotor. Hard to see the p/n but looks like 24215. The metal center piece is floating as well and I can see a thin metal strip under it. The cap center is spring loaded. Am I missing something here?
That rotor is made that way. That spring steel is supposed to allow the center to float. It is the correct one for that cap. Later rotors have the center hard mounted but when they did that, they also changed the contacts in the cap. So you should not mix and match.
Fixed rotor goes with center carbon button and spring.....................flexible rotor goes with fixed solid center button.. Caps have different terminals....
So....my rotor is floating and the cap has the spring loaded center carbon button. Sounds like it is not the right combination. Any one have a p/n for the right rotor?
Working on a couple today , the brown fixed rotor is # 4215 and the NOS accel replacement is # 130401
Bringing this thread back to life….. I run a 409 Chevy with a Double Life dizzy……the center button came out of my lower cap forcing me to start searching. I received an NOS Mallory 24001 (black) cap in the mail today with the flat contacts….mine had notched contacts (brown/#4004). I also have a notched NOS cap coming…. Your thread explains the difference and which rotor to use with my caps and I wanted to thank you for such a great piece of information. will probably look for a long rotor to put with this cap and hold as a spare and continue to use the notched cap when it comes. was there a performance +\- using either cap or was it just a design change?