C-3 Distributor ID

[Steve L.]

Re: C-3 Distributor ID

I have the original dist. from my 73 build 20142 L48
I can have a look at these holes but can someone post a picture of what to look for. I can also check the vacuum can number.

Steve L
73 coupe since new

[Joe L.]

Re: C-3 Distributor ID

I have the original dist. from my 73 build 20142 L48
I can have a look at these holes but can someone post a picture of what to look for. I can also check the vacuum can number.

Steve L
73 coupe since new

Steve-----


Here's what to look for as far as the distributor housing is concerned. The housing on the left has the hole (for the internal nylon thrust button); the housing on the right does not have the hole.

[Christopher K.]

Re: C-3 Distributor ID

Thanks for the offer, Steve, that would be great.
Hope this is legal but here's a link to an early '73 454 dist, a 1112114, dated 2F 28. There's a good pic of the hole opposite the tach drive gear.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=260339704900&indexURL=0&photoDisplayType=2#ebayphotohosting

Chris

[Steve L.]

Re: C-3 Distributor ID

I can see what to look for. Thanks Joe and Chris,

I'll look tomorrrow since I have the dist stored in my shed and it's dark out there right now.

Steve L
73 coupe since new

[Steve L.]

Re: C-3 Distributor ID

My 73 (build 20142) distributor with tag 112098 Delco Remy 3C29 has a hole for the tach drive but there is no thread in the hole.

This is absolutely definitely an unmolsted (except for points and condensor)original distributor.

I don't see any numbers on the vacuum can.

Steve L

[Joe L.]

Re: C-3 Distributor ID

My 73 (build 20142) distributor with tag 112098 Delco Remy 3C29 has a hole for the tach drive but there is no thread in the hole.

This is absolutely definitely an unmolsted (except for points and condensor)original distributor.

I don't see any numbers on the vacuum can.

Steve L

Steve-----


There should be NO threads in the hole. The one that I pictured did have the hole threaded but that feature is not original to ANY Corvette tach drive distributor. The threading is ALWAYS a retrofit type of thing to facilitate the installation of a set screw to control thrust and be used in conjunction with a cross gear with a brass button installed on the end. I only pictured that one to illustrate generally how the HOLE should look since it was the easiest one to get my hands on at the moment.

[Christopher K.]

Re: C-3 Distributor ID

Thanks Steve, I really appreciate the trip to the shed! You sure are lucky to have your original car.

Joe, thanks for all the details. Since my car is a Mar 15 build, it seems possible that my distributor is up to six months older. I sure would like to hear from some other '73 L82 owners. I just don't want to go to all the trouble and expense of replacing it, and then find out it wasn't necessary.

Chris

[Joe L.]

Re: C-3 Distributor ID

Tim,
After some cleaning and a little mirror manipulation I was able to look at those numbers. They are CCW 524 - I'm very sure it's not a 7.

I also did a little surfing on Fleabay and saw a listing for an nos '70 TI distributor. It also had the MS 201 15 vacuum can.

Thanks for the good info, I would have never looked there.

Chris

Chris----


As far as I can determine, the cam and weight plate stamped "CCW 524" is a GM #1851057 and that is the cam used for 1973-74 Corvette applications with L82. It's possible that there was more than one stamping used for the 1851057 but I doubt it.

The GM #1112130 distributor was, essentially, a PRODUCTION-only part number. It was available in SERVICE but only for a VERY short period of time---from September, 1972 through January, 1973. At that time, it was replaced by the GM #1112150 which was used in PRODUCTION for 1973 L-82 with THM and most 1974 L-82's. I can find NO component parts differences between the GM #1112130 and the GM #1112150. There must have been some sort of difference but, from what I can determine, it must have been VERY subtle. Since the 1112150 replaced the 1112130 for SERVICE, I really doubt that there was any significant difference between the two, especially considering how early the replacement occurred. In fact, I would not be a bit surprised if some later 1973 Corvettes with L-82 and 4 speed were originally built with the GM #1112150 distributors.

Both the GM #1112130 and 1112150 utilize the following components. These are the components that, basically, fully account for the performance differences between distributors:

cam and weight plate-----GM #1851057

advance springs----------GM #1851056

advance weights---------GM #1881371

shaft and automatic cam--GM #1870718

breaker plate-------------GM #1876641

vacuum control-----------GM #1973448

Component-wise, an AS-ORIGINAL 1973 GM #1112150 should be exactly the same as a 1974 GM #1112150. And, by extension, a 1974 GM #1112150 should be, COMPONENT-WISE, the same or virtually the same as a 1973 GM #1112130.

Unfortunately, NONE of the aforementioned distributor parts remain available from GM; most have been discontinued for more than 15 years. In addition, NONE of these parts is stamped with a GM part number which makes identification of used parts very difficult. The vacuum control is stamped with a derivative of the GM part number (i.e. "448"), so it can be easily identified. The auto cam (brazed to the top of the mainshaft) and the cam and weight plate are stamped with codes to identify them, but I do not have cross references for all of them to part number.

As Bill described in his post, though, just about any 1971-74 Corvette distributor (or, even earlier distributor) can be configured on a distributor machine to match the performance characteristics of the GM #1112130 or 1112150. When that is done, one has the exact equivalent of those distributors. Attach the proper ID band and no one could externally or performance-wise tell the difference. In fact, only an INFINITESIMALLY SMALL number of folks could tell the difference if they were to "dissect" the distributor.

[Christopher K.]

Re: C-3 Distributor ID

Thanks Joe, that information is incredible! I never realized the difference between the 2150 vs 2130. I always assumed the 2130 was neither a production or service part, since I have never seen one. Thanks for the list of part numbers also, which is extremely helpful.

I am now, again, very curious as to whether my distributor is original. I have the correct cam and weight plate but no "hole" for the tach drive gear. Would someone actually replace the body or cast iron housing and not the cam? Seems unlikely to me.

Thanks again for the informative reply,
Chris

[Joe L.]

Re: C-3 Distributor ID

Thanks Joe, that information is incredible! I never realized the difference between the 2150 vs 2130. I always assumed the 2130 was neither a production or service part, since I have never seen one. Thanks for the list of part numbers also, which is extremely helpful.

I am now, again, very curious as to whether my distributor is original. I have the correct cam and weight plate but no "hole" for the tach drive gear. Would someone actually replace the body or cast iron housing and not the cam? Seems unlikely to me.

Thanks again for the informative reply,
Chris

Chris----


The GM #1851057 cam and breaker plate was not unique to the GM #1112130 and 1112150 distributors. It was used for other distributors, including non-Corvette. So, just because the distributor you have may have the correct cam and breaker plate, that does not necessarily mean that the rest of the distributor is correct.

On the other hand, I've never been absolutely convinced that all 1970-72 distributors, possibly including early 1973, had the cross gear thrust button and, consequently, hole in the distributor housing.

[Thomas H.]

Re: C-3 Distributor ID

Jim-----


That's good information. I've never been really sure when the addition of the thrust button actually occurred. I've done a little research on the matter and it now appears to me that the change might not have occurred until sometime in the 1973 model year.

It would be interesting to hear from folks with 1970-73 Corvettes with distributors that they're reasonably sure are original to the car and unmodified with respect to the thrust button.

Joe,

FWIW

The original dist in my 71 LS5 has no hole in the housing.

Tom