C1-C3 Delco Ignition Points -- how to identify ?

[Wayne M.]

Want to know how to tell the difference between D-106P (1931988) and D-112P (1966294?). Here's what I know from the two NOS sets in the picture.

Both have Delco Remy made in USA stamped on the bottom. The set on the left, in addition to the Delco Remy you can see on the arm near the pivot, has "PAT 2865726" on the bottom. This set came mounted on a "Plate Shield Pkg." (breaker plate, condenser, points set, 2-piece radio interference shield, ground lead, and misc screws). Box reads part # 1876065, with instructions dated 1972. On the right, the set came in a box clearly identified D-106P and 1931988.

At first glance, the main difference is the orientation of the attaching slots. Both fit on all distributor single point base plates. I pushed the cam rubbing block on both and about the same amount of spring tension was felt. But I understand that the D-112P is considered "high performance", so I'm wondering if the set on the left side is D-112P, or just another iteration of D-106P ?

Seems that the D-112P was used '66-up on all high performance motors (427's, LT-1's), with no grandfathering back to previous high performance distributors (L84, L76, etc).

I realize there is also a variation with suffix "PS" which I understand may mean the condenser and ground leads are attached with a screw, instead of just sliding the spade connector against the spring.

So is D-112P points set something entirely different from what is shown in the picture ? There's many offered on eBabe with this number (at a substantial premium over D-106P), and I'll be danged if I can see the difference.

[John H.]

Re: C1-C3 Delco Ignition Points -- how to identify

Wayne -

I believe the D106 series has 19-23 oz. spring tension, and the D112 series has a stronger 28-32 oz. spring for high-rpm SHP usages.

[Duke W.]

Re: C1-C3 Delco Ignition Points -- how to identify

I don't believe either set in the photo is D112P. First, D112P as I recall only had a screw teminal. There was no clip on terminal type, and I don't think they were ever sold as an "assembly" with other parts. Second, you should definitely be able to distinguish the 28-32 oz. D112P breaker arm tension from the 19-23 oz. point sets. Also I believe the D112P had a larger contact surface area, which also visually distinguishes them from lesser point sets.

IIRC the D112P type showed up about 1966, and was OE and specified as replacement for some GM division high performance engines, but I don't think Chevrolet ever used them as OE for any engine.

As you say, they were also never specified in parts manuals as "retrofit" for previous high revving Chevrolet engines, but in my experience they are absolutely necessary for mechanical lifter engines if you want them to rev cleanly to 6500, along with tight shaft end play, snug bushings, and a wobble-free breaker plate.

Since this is probably a good time to review Delco points, I believe the early D106P had a screw terminal. Later versions had the clip on, but the screw terminal type were still offered as D106PS. There was another version for single point V-8 distributors called D109P, but I forget how they differed from the 106.

Maybe someone else can correct me if I'm wrong and fill in the details.

Duke

[Chris Patrick]

Re: C1-C3 Delco Ignition Points -- how to identify

The D-112P points that I have look just like the D-106P except that careful examination shows a larger contact point like the one on my right (tan insulator) in your picture. None of the three (and one of them is at least 25 years old) have the mounting slots like the one on my right.

They are all straight out on the adjustment end and perpendicular on the pivot end like the one on my left (brown insulator).

[Paul B.]

Point Deduction...???

for incorrect ones???

[Gary Schisler]

Re: Point Deduction...???

Why would there be since the only thing they look for is the point adjusting hex head.

Gary

[Wayne M.]

Good one, Paul -- another reason to go K66 *NM*