I’ve got my hands on the mysterious dual-point dizzy and I have good reason to believe that it is an example of the Harman-Collins speed part from back in the day.
Delco Remy made a variety of distributors based on the same basic foot-print – many for non-GM marques - each carried a unique model number. AFAIK the last year for the external riveted brass tags for Chevy was in late ’48 early ’49 production (1110 prefix model #s). Strangely, the ’57 Parts Master suggests that the dizzies for ’53 were the first with no external tag . . . (part No. on plate) . . . AFAIK the transition occurred much sooner in ’49 (1112 prefix model #s).
This example is model 1110008 – designed for ’37-’39 216 – it was California Bill’s preferred dizzy because of the advance curve. Note the orientation of the hot-wire stud and the grease cup.
Now look closely at the same orientation in the Harman-Collins advertisement:
The conversion process included welding the stock hot-wire stud hole closed and creating a new one about 90 degrees away from the stock location. Another major difference is the size of breaker-cam:
The stock cam is a small flat sided affair with very pronounced sharp peaks. The Harman-Collins cam is much larger in diameter with a more gradual rise to less pronounced peaks. With the placement of the points 180 degrees apart it would seem that the breaker events would be almost simultaneous. But as we’ll see when we inspect the point sets (and placement) there is a leading set and trailing set.
For comparison’s sake lets look at some stock plates first:
The early plates have no markings whatsoever as the model & serial numbers are on the external tag – moreover Delco changed the design of centrifugal advance weights sometime in the early 50’s eliminating the extra riveted payloads – leaving just flat stock. Note the placement of the point set – very close to the center of rotation – with the hot lead and capacitor/condenser lead attached directly to the hot-wire stud. On a side note, I prefer the Delco original point sets (with the bakelite cam follower). They don’t seem to wear at all if kept lubricated. While the later aftermarket nylon style wear out quickly – they seem to succumb to heat regardless of lubrication.
Compare both with the Harman-Collins modified plate:
it is based on a Delco 1112353 model – late ’49 early ’50 216 applications. The stock fulcrum is retained but the point set is rotated away from the center (given the larger breaker cam). A new eccentric adjustment is fitted and new lockdown set-screw is fitted just to the north and east of the (now vacant) stock eccentric hole. Opposite the stock point-set location is the now empty condenser retainer screw hole. In the adjacent open real estate is a second fulcrum post (of larger diameter) positioned closer to the center of rotation. An eccentric and a lockdown set-screw are also fitted (partially obscuring the model/serial numbers).
The engineering and construction seems quite sound and well executed:
designed to hold the point-sets firmly in place and thereby holding tune.
As for the point sets – they are both transplants from other stock OEM applications.
The set on the left seems to be repurposed from 1940’s Caddy:
https://brillman.com/product/autoliteprestolite-distributor-contact-points-3/ The set on the right seems to be repurposed from 1940’s Buick/Olds/Pontiac
https://brillman.com/product/delco-distributor-autolite-contact-points/ The design is well thought out and professionally executed. The presence of a Scintilla condenser a cherry on top!
