Who is the guru on distributor caps?

[Tom Parsons]

Specifically, I'm interested in the following variations of single window versions, when they were introduced/available and engines used with:
Brown or black, short/tall plug wire towers, Patent Pending with an R, Patent number with an R and without an R.
I'm sure this info is found in all the judging manuals, but I don't have, nor need, all the judging manuals.

[Jack H.]

Re: Who is the guru on distributor caps?

Yes, it is in the JG books. Forgetting 6-Cyl cars ('53-55), things started with a non-windowed D305 cap. This has Delco Remy script logo on the inside of the cap and circular depressions in the Bakelite between outer plug terminal posts. It was used on V8 from '55-'57, then continued in use on dual point/dual 4-Bbl cars to '61.

In '58 the conventional windowed cap (D308) came along and was pretty much the standard until HEI. For '58-67, JG books call out the 'Delco Remy' + 'Pat Pending' and no 'R' marks. In '68 & '69, emboss with and without 'R', with 'Pat Pending' or 'Patent 2769047 are all allowed. In '70-74, caps are considered correct with 'Pat Pending', and 'R'.

The brown alkyd version of this cap is considered correct for L88/ZL1 engines. '63-65 FI cars are considered correct with a D310 cap (upper wire towers are slightly shorter to accommodate ignition shielding clearence) having the same emboss marks as D308 windowed caps of that era.

'58L-62 FI engines used a D324 cap which is similar in structure to the D308, but it has TWO point adjust windows. Those want to have 'Delco-Remy', 'Patent Pending' and no 'R' emboss.

That's a quick survey of the 8-cyl Corvette dist cap waterfront. Some say the 'R' on the caps indicated 'ballast resistor', but having electrically probed both R and non-R caps, I can't see a difference. Also, I pulled US Patent 2769047 and the sequence of events makes NO SENSE to me based on past experience with patent law....

The patent was granted WELL in advance of '58 car production. Ergo, you'd think the objective would be for GM to protect its intellectual property and disclose the patent number protecting the invention. A 'Pat Pending' disclosure is typically put on inventions during the period when the invention has been submitted to the patent office, but a decision to grant/deny has not yet been made....

I have found a sample of a Patent 2769047, no-R, D308 distributor cap that has a 'wierd' Delco Remy emboss.... The words 'Delco Remy' are highly stylized, almost a script vs. block letters. I wonder if the 'R' didn't come along as part of a scheme to trademark the Delco Remy brand name? If so, the 'R' could be indicating the REGISTERED trademark process.

[Tom Parsons]

Re: Who is the guru on distributor caps?

Everything you say makes sense except the D308. The boxes I have with the D308 caps are the later (cheaper), alum terminal, no script, made in Mexico style. I have several caps in sealed boxes (some with metal caps and a pull string to open the box) which are labeled D309R (part number 800061).