Big Block Distributor Hold Down Clamp

[Camarocards]

Which hold down clamp is correct for a '68 396/325? The wire type or the plate type?

Thanks,

Bob

[bertfam]

From the start of V8 production in 1955, all engines used the solid (stamped) steel clamp you show in the top picture. This was P/N 3704912.

Then, in late 1959 (for the 1960 model year), GM went "cheap" on us and used the wire clamp you show in the bottom picture. This was P/N 3772532 and used a "retainer" (P/N 3770598) to keep the legs from spreading.

Then, in early 1968, GM went BACK to the solid (stamped) steel clamp you show in the top picture (P/N 3704912). Apparently the wire clamp couldn't do the job, so in a rare move, GM went back to something that actually worked!

Now, as to which one you should have, it really depends on the build date of your engine. Very early 68 engines could still have the wire clamp. They were phased out, but still intermittantly used in early 1968 because of what they had left in inventory. Toward mid year production, the wire clamp had mostly dissapeared and the solid clamp was now prevalent.

Hope this helps.
Ed

[Camarocards]

Ed,

Thank you very much! Very helpful indeed.

I have both the wire clamp and the stamped clamp in my stash of parts, hence my question on which one was correct.

My car is an 01D build so from the info you've provided it looks like it could be a toss up on which one to use. Now, if I go with the wire clamp version what finish would it have gotten? Would it have the overspray from when the engine was painted (assuming of course that the distributor and clamp was installed prior to the engine being paint)?

Thanks,

Bob

[bertfam]

I believe the wire clamp was black oxide (as was the bolt) and the retainer was natural steel. The stamped clamp was usually natural, but some examples have been seen with varying amounts of orange paint on them. Supposedly, both Flint and Tonawanda painted the engines before the distributor (and clamp) was installed, so you shouldn't see any orange paint on the clamp, but I'm wondering if maybe some of the clamps were installed loosely before paint. I'll ask John and/or Jerry to comment on this.

As for which one to use, what's the build date of your engine?

Ed

[Mike S]

I checked both my '67 L35's and they have the stamped clamp.
They are: original unrestored survivor - T0214MZ - 4B LOS and restored convertable T0308MW - 5B NOR

Mike

[Camarocards]

Thanks Mike.

Ed-The engine is a January '68 build. Don't know the exact date since I'm not in frontbofbit at the moment.

Thanks,

Bob

[bertfam]

I checked both my '67 L35's and they have the stamped clamp.

There may be a difference in usage between small blocks and big blocks, so I'll see if John or Jerry can elaborate.

Ed

[Jerry@CHP]

What I can add here is the wire style was used on 67 and 68's.  But, I'm not sure on the BB cars.  I'll have to dig though all of my survivor photos and take a look.

In the Nov '68 Super Stock magazine article with Jerry Stahl and the '68 Z28 road test, they talked about how they did not like the wire style hold down as the timing kept moving around while doing their road test.

Jerry

[Steve68]

My 68 L78 has the wire hold own clamp (original). 06 build.

Steve

[1968 Z28]

My 1968 Z28 07C, 06-19 engine build, has the stamped steel hold down.  The hold down and the bolt were painted silver.  Apparently they were painted with a brush as there was some silver paint on the distributor wire.  It doesn't look like it was sprayed on the wire, it appears that a paint brush left the paint.

[Camarocards]

Jerry,

I've been following a similar thread on distributor clamps but it had more to do with small blocks and the correct finish. My question was more aimed more at big blocks and which type clamp was used. The type of finish will then of course need to be answered as well.

Perhaps other members can take a peek at their big block engine and report back what type of clamp is installed and what month the car was built.

Thanks,

Bob

[1968 Z28]

Bob....Can't think of any reason they would use different ones for different engines.  All the engines, big block or small block, would get the same part as they came down the engine assembly line.

[Camarocards]

Jerry,

You would think so, right? It would seem to make sense. I'm just not sure which one to use since I've seen both type clamps advertised.

I just had a friend check his '69 427 Corvette he is restoring and it has the wire type clamp. Go figure? I even asked him to check the NCRS judging manual but unfortunately the manual makes no mention of distributor clamps.

[JohnZ]

<< Now, if I go with the wire clamp version what finish would it have gotten? >>

Which hold-down version doesn't affect the finish - they were installed (with the distributor) at both engine plants prior to engine painting, and masked with a coffee can, and it's not unusual to see engine orange overspray on the distributor lower housing and on the hold-down.

[bertfam]

I just had a friend check his '69 427 Corvette he is restoring and it has the wire type clamp. Go figure?

My 69 427/390 Corvette (VERY late October, 1969 build) has the stamped clamp! And no, the 68/69 (latest - 5th edition) Corvette Technical Information Manual and Judging Guide, doesn't mention the clamps.

Ed