Distributor Hold Down Bracket - 1960

[Joe M.]

Anyone have a photo of an original stamped steel hold down bracket?

How does the current reproduction hold down bracket differ from the original?

My December 1959 build car has the wire hold down now, but informed that it is incorrect for the car.

[Joe L.]

Re: Distributor Hold Down Bracket - 1960

Anyone have a photo of an original stamped steel hold down bracket?

How does the current reproduction hold down bracket differ from the original?

My December 1959 build car has the wire hold down now, but informed that it is incorrect for the car.

Joe------


Attached is a photo of a GM #3704912 which is the clamp that was SUPPOSED to have been used for your application.

There were at least 2 part numbers that were supercessive to the 3704912. Each of these is 100% functional but configured slightly different. I think I've posed a photo of all of these in the past.

[John S.]

Re: Distributor Hold Down Bracket - 1960

joe, you better look at your past posts. look up "distributor hold down clamps." what you posted on dec. 13, 2008 is not what you state today. i have the pictures of the clamps posted in that tread in my files and if the information was wrong i would like to update it.

[Joe M.]

Re: Distributor Hold Down Bracket - 1960

John, I saw his post a few days ago, but could not find it today by searching for "distributor hold down bracket." i will look for the year.

[John S.]

Re: Distributor Hold Down Bracket - 1960

Anyone have a photo of an original stamped steel hold down bracket?

How does the current reproduction hold down bracket differ from the original?

My December 1959 build car has the wire hold down now, but informed that it is incorrect for the car.

accepted time of the wire clamp appearance is january of 1960. in bob baird's 58 to 60 restoration guide, page 69, there is a wire clamp that is on a original distributor dated 9M2 (1959 december 2). also on page 69 is the earlier stamped steel clamp that joe posted a picture of. the picture of this distributor is on a restored vehicle and dated 0A13.

[Joe L.]

Re: Distributor Hold Down Bracket - 1960

joe, you better look at your past posts. look up "distributor hold down clamps." what you posted on dec. 13, 2008 is not what you state today. i have the pictures of the clamps posted in that tread in my files and if the information was wrong i would like to update it.

John------


I am aware of that post and was aware of it when I composed the one in this thread. You will note that I used the term "I believe" several times in that post. Over time, some beliefs change as more is learned.

At the present, I doubt that there were two completely different versions of the 3704912. I don't rule it out, but I now doubt it. However, I do know that the clamp I pictured above as well as the one I pictured on the far left side of the photo in the December, 2008 thread is a GM #3704912. The one in the previous photo is NOS from a GM package that is labeled with that part number.

One curious thing, though: the description of the 3704912 that is found in C1-era P&A catalogs says that it has "one 13/32" hole". At least that part of the description is more consistent with one of the other clamps pictured in that thread by another poster. This is where I originally came up with the idea that there were 2 completely different designs for the 3704912. That's contrary to GM normal practice 99% of the time but there's always that 1% of the time.

As far as the "wire" type clamps go, I just don't know. I do know that they were used for 1963-67 but that's about it. However, there is a curious thing in parts references. For 1955-59 Corvettes, there is cataloged the GM #3704912 CLAMP. For 1960-62 there is cataloged GM #3772532 CLAMP UNIT. The clamp unit is either a GM #3704912 clamp with an included mounting bolt OR it's the wire type clamp with retainer and bolt. I don't know which.

[John D.]

Re: Distributor Hold Down Bracket - 1960

Lately for some reason I have been getting a lot of calls on what is correct distributor hold down clamp for 59 to 62's.
1. 58 to 60 JM on page 59 of 4th edition states," THe distributor is secured by a stamped metal clamp,held in place by a hex head bolt...."
Logo on that bolt are UR WC2B and E.
"Wire type hold down was not used on Corvette"
2. Forgetting I ever heard or read a judging manual my personal observation is that 57 to at least 60 used a pie shaped clamp (not like Joe Lucia's photo) that had a round hole for the bolt (not the oval bolt hole).
Now that's what I knew and have observed but that doesn't mean anything.
3. 61-62 Judging Manual states that ALL of those distributors no matter carb or FI -ALL use the wire clamp.
4. 63 to 65 use a wire clamp

Recap: 57 to 60 = solid steel clamp
61 to 65 wire clamp.

[John S.]

Re: Distributor Hold Down Bracket - 1960

Joe------


Attached is a photo of a GM #3704912 which is the clamp that was SUPPOSED to have been used for your application.

There were at least 2 part numbers that were supercessive to the 3704912. Each of these is 100% functional but configured slightly different. I think I've posed a photo of all of these in the past.

#3704912 was the clamp used in 1955. in 1955 this clamp was pie shaped and did not have a oblong hole. these clamps are sold on ebay by engineslimited ( "corvette distributor hold down" ). enginelimited list these clamps as coming from 56-60 corvettes.

[Joe L.]

Re: Distributor Hold Down Bracket - 1960

#3704912 was the clamp used in 1955. in 1955 this clamp was pie shaped and did not have a oblong hole. these clamps are sold on ebay by engineslimited ( "corvette distributor hold down" ). enginelimited list these clamps as coming from 56-60 corvettes.

John------


In that case, the configuration of the 3704912 changed significantly at some point. The one I pictured is the original clamp from my 1969 and it is identical to another NOS GM #3704912 that I have in a GM package (pictured in my post from December, 2008).

[Stuart F.]

Re: Distributor Hold Down Bracket - 1960

I know the importance of using the right clamp to be correct, but I personally hate the wire clamps and the Engineer who designed them. I have the one from my 63 in my parts bin somewhere, probably looks like new. I can struggle with two pieces and get things right, but those three pieces usually require some diassembly including the PCV tube/hose on a 63 (carbureted). I can loosen the metal clamp all day long to readjust the timing with the shielding, vacuum line and PCV tube/hose in place, but with a wire clamp - one turn too loose on the bolt and you may have to fish around all day to get the wire clamp reset right. I have several plate clamps and will keep using them till the day I expire.

Stu Fox

[Gary C.]

Re: Distributor Hold Down Bracket - 1960

'56-7 distributor hold down clamp Gary....

[John S.]

Re: Distributor Hold Down Bracket - 1960

'56-7 distributor hold down clamp Gary....

your clamp looks like the one gary pronesti sells. 55,56 and 57 have the same part number. if this is what the 56 and 57 originally had it is different than than the ones i find in 55. the shape of the bracket is the same, but as you view the bracket on the car the 55 bracket is smooth. yours shows a indentation on one side and a raised surface on the other.

[Gary C.]

Re: Distributor Hold Down Bracket - 1960

'57 Bowtie car distributor hold clamp. Sorry, but there's no weld on the one I previously posted. It's an original that was glass beaded and replated. Gary....

[John D.]

Re: Distributor Hold Down Bracket - 1960

Nice epics of the clamp Gary.
It's easy to spot a repro guys/girls. The repro clamp is not near as distinct as Gary's. Distinct means the indentation on one side and protrusion on the other side on Gary's is quite pronounced. The repro just has a hint of the indent.

[Joe L.]

Re: Distributor Hold Down Bracket - 1960

I know the importance of using the right clamp to be correct, but I personally hate the wire clamps and the Engineer who designed them. I have the one from my 63 in my parts bin somewhere, probably looks like new. I can struggle with two pieces and get things right, but those three pieces usually require some diassembly including the PCV tube/hose on a 63 (carbureted). I can loosen the metal clamp all day long to readjust the timing with the shielding, vacuum line and PCV tube/hose in place, but with a wire clamp - one turn too loose on the bolt and you may have to fish around all day to get the wire clamp reset right. I have several plate clamps and will keep using them till the day I expire.

Stu Fox

Stu-----


The wire-type clamp was one of the dumbest ideas that Chevrolet came up with. They finally recognized the mistake and went back to the solid-type clamp about 1968.