Question on Mallory distributor

A friend gave me a Mallory dual point distributor
that he took out of another project. I thought I would
like to put it in a 66 FoMoCo 289 , but this
distributor has no vacuum advance. What is this
things intended purpose? Thanks, Fritz

Maybe drag racing, not much vacuum there.

Probaly racing or marine. A modern pointless distributor is superior in nearly every way. You need the vacuum advance. Performance Distributors makes distributors right here in Memphis and sells them though Summit Racing and other places.

They were used back in the pre electronic days, mostly for high revving engines. The dual points stabilized the spark somewhat, gave the coil more saturation time at high RPM. Points bounce when they close, the dual points helped get more power stored in the coil before it was time for the next discharge. Also one set was timed slightly ahead of the other, helped the life of the points, kept them cleaner.

The reason for no vacuum advance, it was intended for full throttle performance, not economy cruising. A vacuum advance is out of the picture under those conditions. You also want repeatable performance, a vacuum advance is just something to go wrong.

Marine engines usually run without vacuum advance because they run at full load and rpm mostly. Tractors don't use it because they are mostly run at a steady rpm. Some hot rodders swear by vacuum advance and others curse it. Spend some time on some street rod forums and you will get lots of opinions on this.

Back in the fun days we ran them and like said we did it for max performance . We would Build a timing curve that would work for what we were doing . I played a lot with Mopars and Fords Ford had a Factory dist that had no vac advance that was used on the small block and one for the 427 Dual points were also used Mopar had a factory dual point for there engines . I had worked up timing curves that worked well and set up god only knows how many dist. Mallory , and Holley made them also . I preferred the factory ones and the Holley . Tricking out a centrifugal is a lost art . Ya had a lot to figure in , is it a Automatic trans or a four gear , what gear ya going to run . what cam and where is the power curve of the cam how many RPM ya going to try for . What engine . I would buy brand new factory dual points and build a curve that would enhance the performance and take them out to a local drag strip and watch guys do there time trails and if he was not getting what i thought he should be running i was like the guy on the street corner in the trench coat with the PISSSST HEY BUDDY ya want to go faster have i got a deal for you . Back then my cost on a new in the box factory dual point from Mopar was 19.75 and hour on the dist strobe doing a recurve and sell them for 50 and and extra 25 for setting it up in the car . This would give then about a half second gain from factory stock. The drive way at my parents house on Wednesday and Thursday evenings from 6-10 was packed with guys getting ready for Friday evening , Monday and Tuesdays were for working on dist. I had a Complete SUN set up with the 102.0 scope and a 505 Dist. Strobe

The high performance Chevy engines, such as in Corvette were also from the factory, no vacuum advance & dual point.

Looking at some Shelby Cobras in a museum, I saw a lot of then had Delco distributors, not sure if they were factory or custom replacements.

The caps were on, so couldn't tell if they were dual point. I assume not as they had a window type cap.

Well even on the Shelby's they ran the FORD Dual point . The Ford dealership i worked at was a Shelby dealer and since most of my work was on the performance end i worked on them . Did a lot of shell we say upgrading the small blocks . Say you had a Mustang with a 289-302 2 BBL and you wanted to get a WEEEeeeee bit more out of it . So we would remove the old Lumpty stick and install a brand new off the shelf C 9 OZ 6250 C with a set of anti pump ups a new 4 BL intake shim the stock valve springs .010 add a 600 CFM holley a factory dual piont recurved and factory dual exhaust with low restriction mufflers . That would wake up a lazy old 289-302 up do a little on upping the trans pressure stiffen up the shifts on the slush boxes and under WOT she would squak the tires going into second and you were now down in the low 14's . I tricked out a neighbors kid's 65 Mustang a little more and he was having fun giving 383 stock Road Runners a rough way to go as he was down in the high 13's . wonder what ever happened to that kid ????Kid he was like 6-7 years younger then me . Lost track of him when i moved out of home after my girl fiend and i broke up and i left the area .

Not alot of people would understand the C90Z6250C but I remember that one well!! 50 years ago, that was my go to cam for waking up the small block Fords..a short time later they were no longer available..Ford sold all of them to Holman-Moody and were unobtainable.