C2 (2 1/2") Exhaust Clamps --- Again---

[Alan D.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Dave, at the present time I Agree with you!
We really need to be looking at the nut - pn 1359887 changed in 1979 to 271184. It is used in hundreds of locations throughout GM. As I recall the clamp assy did not exist in production it was a nut, washer, U-bolt with their own pn.
Take a look at the AIM for your year car to confirm.
One more point to confuse us, there are clamps (U-bolt section) that have part numbers embossed on them without the circle 2 1/2 stuff.

[Gary B.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

... As I recall the clamp assy did not exist in production it was a nut, washer, U-bolt with their own pn....

Alan,

I don't think that was the case. For example, the nut is called out explicitly in the '66 AIM. I think service replacement clamps came as a complete set of parts, i.e.., with a combined part number for the entire set.

Also, I believe that at least some service replacement clamps had part numbers stamped into the saddle, but I don't think production line clamps did. At least I haven't seen any on '64-'67 cars. I don't know about the unusual dual clamp used at the mid-pipe location on '63s. Perhaps someone has an original of that clamp they can look at.

Gary

[David L.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Dave, at the present time I Agree with you!
We really need to be looking at the nut - pn 1359887 changed in 1979 to 271184. It is used in hundreds of locations throughout GM. As I recall the clamp assy did not exist in production it was a nut, washer, U-bolt with their own pn.
Take a look at the AIM for your year car to confirm.
One more point to confuse us, there are clamps (U-bolt section) that have part numbers embossed on them without the circle 2 1/2 stuff.

Alan,

GM # 1359887 does not appear in my Mar. 1971, June 1974, May 1976, or Jan. 1978 Chev. Price Schedules. However, GM # 271184 is listed in Gr. 8.917 at a list price of $0.10 (1971 & 1974), $0.11 (1976) and $0.14 (1978).

According to my Jan. 1976-Dec. 1981 GM Parts History catalog GM # 1359887 was replaced with GM # 11501869.
Also GM # 271184 was also replaced by GM # 11501869.

Dave

[Alan D.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Gary "I don't think was the case. For example, the nut is called out explicitly in the '66 AIM. I think service replacement clamps came as a complete set of parts, i.e.., with a combined part number for the entire set." Yes, think that was my point. The 63, 64 AIM also list these as unique parts, only service parts came as completed clamp.
and "Also, I believe the some service replacement clamps had part numbers stamped into the saddle, but I don't think production line clamps did" I looked at clamp again and checked books & agree the pn on the saddle is an ASSEMBLY Number, as you suspected, so we agree on that too.

Dave "According to my Jan. 1976-Dec. 1981 GM Parts History catalog GM # 1359887 was replaced with GM # 11501869." I show the same thing however I also see a change in the 1979 book of # 1359887 replaced by 271184, and then again in 1981 as you mentioned. As noted the 1359887 nut was called out for use on hundreds of GM cars even into the 93 model year. We agree on the replacement number history, it seems our timing may be a little different, no biggie.

[Bob J.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

I'm pretty sure factory installed tail pipe clamps on 63s had GM and a part number.

63 (2 1/2) inch exhaust center exhaust hanger usually had a letter W stamped in ......but not always.

I've never seen a service "883" clamp from GM not having a GM part number stamped in the saddle.


IMHO .....GM used clamps with part numbers stamped in the saddle for 1960s service clamps and on factory installed 63 tail pipe clamps.

Bob Jorjorian

[Gary B.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

I know the '63 front to mid pipe clamp was that double beast, which was replaced by single clamps for '64-'67. But how did the tail pipe tip clamp differ from '63 to later?

Gary

[Bob J.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

I know the '63 front to mid pipe clamp was that double beast, which was replaced by single clamps for '64-'67. But how did the tail pipe tip clamp differ from '63 to later?

Gary

I don't think the tail pipe clamps changed from 63 through 65............they might be the same through 67.
I've been involved in 63s since 1970 so that is the year I'm most sure of when I state 63 had GM & numbers in the rear clamps.
The AIM pages for rear clamp parts appears to be exactly the same in both my 63 and 65 manuals.
I don't own a 66 AIM and my 67 AIM is loaned out.
Bob Jorjorian

[Gary B.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Bob,

I can check my '66 AIM this evening for the tail pipe tip clamp #.

Gary

[Gene M.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Boy a lot of exchange on a poor little exhaust clamp. Regardless of what is called out or what was available in replacement parts the line used what ever was put out. I think you will find clamps with no finish as well as thin filmed phosphate. Also be advised of noted flange nuts as well as regular nuts and lock washer. In any event they were all 5/16-18 thread. Keep in mind these exhaust clamps were standard commercial available at the time and were supplied to various automotive lines. In the day the 2" clamp was most likely a bigger volume commodity vs the 2 1/2" clamp. I have no idea how many suppliers were sourced for the clamps but the pipes and mufflers had at least two, Arvin and Walker.

[Bob J.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Bob,

I can check my '66 AIM this evening for the tail pipe tip clamp #.

Gary

Gary, sounds good.
In 63-65 the rear clamp parts are u-bolt # 3791371, clamp (saddle) #3791357, nut #102634 and lock washer #103320.
Bob Jorjorian

[Gary B.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Gary, sounds good.
In 63-65 the rear clamp parts are u-bolt # 3791371, clamp (saddle) #3791357, nut #102634 and lock washer #103320.
Bob Jorjorian

Bob,

Those four GM part numbers are identical to what's in the '66 AIM.

Gary

[Bob J.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Gary,
I guess 63-67 are all the same.
I got a PM last night stating the 67 AIM lists the same part numbers.
Bob Jorjorian

[Gary B.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Bob,

I've also been told based on one '66 Bowtie example that for '66 there was no part or assembly numbers stamped into the rear tail pip tip clamps. So, either things changed from '63 or perhaps there were two suppliers as a previous poster suggested and maybe one supplier stamp the number and one didn't.

Gary

[David L.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

My 1963 Chev. Parts Catalog lists GM # 3824528 as the U-Bolt for 63 Corvette w/HP, SHP, FI (exc. P.G.) and is described as "U"-BOLT front exhaust pipe clamp (5/16-18)". The 3824528 U-Bolt is also listed in my 1963 Corvette AIM (Sect. L-76, L-76; Sheet 2.00)

GM # 3824528 was replaced by GM # 3853726 in July 1964 as per Chev. Parts History which was then replaced by GM # 3949198 in Oct. 1970.

All 3 U-bolts are listed as 5/16"-18 in my vintage Chev. parts catalogs.

Dave

[Gary B.]

Re: C2 (2 1/2&quot Exhaust Clamps --- Again---

Is there anyone left standing who thinks any of the '63-'67 U-bolt threads on exhaust clamps are other than 5/16"-18 (coarse)?

Gary