D309R brown dist cap . whats it correct for??

[Larry M.]

Re: D309R brown dist cap . whats it correct for??

My recollection, at least a quarter century old at this point, is that the 309's had copper terminal contacts, instead of the aluminum (or otherwise white metal) found in the 308's. I recall the copper was for high-performance applications, providing better electrical conductivity, and therefore a stronger spark. Does your 309 match my description, or prove me to be in the beginning stages of feeble-mindedness?
Larry Maher, #10731

[Joe L.]

Re: D309R brown dist cap . whats it correct for??

Larry-----

You're correct. The 309, either plain 309 or 309R, used copper contacts. The 308, either plain 308 or 308R, used the aluminum contacts. The two cap series were functionally interchangeable.

The thing to keep in mind with these things is that the 308, 308R, 309, and 309R are DELCO part system numbers. These numbers are APPLICATION specific and not necessarily PART specific. They remain the same over many years. Some of those Delco part numbers had 2 or more successive GM "long" numbers associated with them. The 308R, for instance, has had at least 4 GM long numbers associated with it. Each time the GM "long number" changes, the part changes. But, it still carries the same Delco application-specific part number.

So, if one finds a Delco cap out of a box, one MAY be able to identify it as, say, a 308R. Further identifying it as to WHICH 308R it is constitutes another matter.

One more thing: often times when folks see a dark brown cap with the characteristic Delco-Remy script, copper contacts and an "R", they conclude that the cap is a 309R. Not necessarily, though. There were several other Delco caps that used dark brown alkyd material and copper contacts which were NOT 309R. I've seen folks make this mistake on eBay MANY times and pay foolish amounts for caps for obscure applications that make them near worthless. In fact, sometimes I've seen them pay an amount that would have been foolish if the cap actaully WAS a 309R. But, as P.T. Barnum once said............

[Jack H.]

Interesting....

because I've laid several "R" and non-R DR caps on my digi-bridge impedance tester and have observed NO significant difference in reading....

[Dale Pearman]

My Understanding

is that minor dimensional differences were incorporated in "R" caps for use with "resistor" plugs.

Dale.

[Terry M.]

My 2¢ about R *TL*

I believe it stands for "Registered" as in registered trademark, but I have absolutely nothing to support that, except no one has ever been able to show any difference in the distributor caps marked with an R and those without - other than that letter. I'm still waiting for someone to show me the resister or the minute difference in dimension.

There was a slightly different rotor - marked with the letter E stamped on the brass tip - that had a slightly longer brass contact. It was designed to improve emissions, the reason for the E mark.

For someone with the enthusiasm, this subject would make a very interesting article for The Corvette Restorer.

Terry

[Clem Z.]

contactor resistance?

what value of resistance do you see? the reason i ask is because the stock GM HEI center contactor which is a seperate piece has about 6 ohms resistance and if you do not use one made from solid copper with a hi voltage coil you will melt the cap where the contactor comes through the cap top because the contactor overheats.

[Clem Z.]

Re: My 2¢ about R

my memory may be fading but i thought the one with the E was shorter?

[Mark Ring]

Re: My 2¢ about R

If yours is starting to go, so is mine. I remember the "E" emissions rotor as being shorter than the original, non-E rotor. I have some of each out in the garage.

-Mark.

[Clem Z.]

Re: My 2¢ about R

when i build up a HEI for racing i have a special jig i install inside the cap using the hole where the center electrode come through as the centering point and then i bend the outside contacts in to the center so they are closer to the rotor tip. since you can not bend the outside ones on the pre HEI we used the longer rotor tipped one.

[Terry M.]

Re: My memory *TL*

has long gone.

Maybe I should have just stuck to the R comments and forgot about the rotor. You may be right about the length.

Longer or shorter they made a definite mark to indicate the part was different and published information to that end. If the R on the cap meant resistor, or a dimension difference, would you not expect some information about that to be in the training literature of the time? Anyone seen anything? - I haven't. Or maybe I should say I don’t remember seeing it.