C@ SBC Exhaust Man.

[Loren L.]

Are these the correct measurements for the "washer/spacer" used under the exhaust manifold attaching bolts: 1/2" ID "hole"; 3/4" OD;
and 1/4" thick? Anybody with a part #?

[Joe L.]

Re: C@ SBC Exhaust Man.

Are these the correct measurements for the "washer/spacer" used under the exhaust manifold attaching bolts: 1/2" ID "hole"; 3/4" OD;
and 1/4" thick? Anybody with a part #?

Loren-----


Center hole is 13/32", OD= 0.725", thickness= 0.135". Part number is GM #3754153. Discontinued.

[Scott S.]

Re: C@ SBC Exhaust Man.

Are these the correct measurements for the "washer/spacer" used under the exhaust manifold attaching bolts: 1/2" ID "hole"; 3/4" OD;
and 1/4" thick? Anybody with a part #?

Loren,

AMK has one that is very close to the measurements Joe listed: .40 x .74 x .13 thick, it is listed under the GM part number (3754153). I just checked their website, unfortunately they are currently out of stock.

The drawing for this part is located on p. 394 of Noland Adams' Vol. 2.

[David L.]

Re: C@ SBC Exhaust Man.

Loren,

Here are 5 NOS exhaust manifold washers that I bought for my 77 El Camino back in the mid 1980's but never used them. They came in packages of 5.
They actually measure as follows:
O.D. = 0.748" to 0.750"
I.D. = 0.408"+/- (13/32" would be 0.406")
thickness = 0.132" to 0.144"

They appear to be zinc coated.

Dave

[Loren L.]

Re: C@ SBC Exhaust Man.

Thanks to all - Nolan's partial blueprint calls out the finish as cadmium or zinc,

[Joe L.]

Re: C@ SBC Exhaust Man.

Thanks to all - Nolan's partial blueprint calls out the finish as cadmium or zinc,

Loren------


The strange thing is that I seem to recall these exhaust bolt washers to have had a plain steel finish with no electroplating. Even when they are removed and the sides exposed, I just don't recall seeing any vestige of a cadmium or zinc finish. So, this may be one of those rare cases in which the part that GM specified to SERVICE an application was not the same as the part used in PRODUCTION.

[Michael H.]

Re: C@ SBC Exhaust Man.

Loren------


The strange thing is that I seem to recall these exhaust bolt washers to have had a plain steel finish with no electroplating. Even when they are removed and the sides exposed, I just don't recall seeing any vestige of a cadmium or zinc finish. So, this may be one of those rare cases in which the part that GM specified to SERVICE an application was not the same as the part used in PRODUCTION.

Joe,

I agree. I vividly remember removing these washers from brand new engines in the 60's and I definitely don't remember any plating. I remember the finish as being natural.

My guess is that there was a different part number for that application.

[Joe L.]

Re: C@ SBC Exhaust Man.

Joe,

I agree. I vividly remember removing these washers from brand new engines in the 60's and I definitely don't remember any plating. I remember the finish as being natural.

My guess is that there was a different part number for that application.

Michael------


I feel pretty confident that if another part number was used in PRODUCTION, that part was never available in SERVICE. For one thing, if it had been available GM would never have cataloged the 3754153 for SERVICE for the manifold bolt application.

The other thing I seem to recall about these is that they seemed to be completely flat on both sides. The 3754153 is stamped out of sheet stock and is, consequently, ever so slightly "convex" on one side. The exhaust washers were almost like ground and hardened washers, although I'm sure they were not actually manufactured like ground and hardened washers.

[David L.]

Re: C@ SBC Exhaust Man.

My 1963 Chevrolet Parts Catalog (Oct. 63) lists GM # 3836710 in Gr. 3.275 as an intake & exhaust manifold WASHER (11/32" I.D. X 11/16" O.D. X 1/8" thick) for 55-63 ALL, CORVETTE (8 cyl.).

In the same 1963 catalog GM # 3754173 is listed in Gr. 5.383 as a Rear Axle Control Arm WASHER (13/32") for a 58 PASS. (6 are required).

GM # 3836710 was replaced with GM # 3754153 in January 1964.

GM # 3754153 is listed as 13/32" I.D. X 3/4" O.D. X 1/8" thick in my 1965 Chevrolet Parts Catalog (Oct. 64) in Gr. 3.275 and Gr. 5.383.

In later catalogs GM # 3754153 appears in Gr. 3.613 and Gr. 7.874.

Dave

[Joe L.]

Re: C@ SBC Exhaust Man.

My 1963 Chevrolet Parts Catalog (Oct. 63) lists GM # 3836710 in Gr. 3.275 as an intake & exhaust manifold WASHER (11/32" I.D. X 11/16" O.D. X 1/8" thick) for 55-63 ALL, CORVETTE (8 cyl.).

In the same 1963 catalog GM # 3754173 is listed in Gr. 5.383 as a Rear Axle Control Arm WASHER (13/32") for a 58 PASS. (6 are required).

GM # 3836710 was replaced with GM # 3754153 in January 1964.

GM # 3754153 is listed as 13/32" I.D. X 3/4" O.D. X 1/8" thick in my 1965 Chevrolet Parts Catalog (Oct. 64) in Gr. 3.275 and Gr. 5.383.

In later catalogs GM # 3754153 appears in Gr. 3.613 and Gr. 7.874.

Dave

Dave-----

It's possible that the GM #3836710 was the original part number for the washers. That's an old part number dating back to about 1955.

It's also very possible that it continued to be used in PRODUCTION after it was replaced for SERVICE by the 3754153.

Based upon "rule-of-thumb" part number sequence, it would seem that the 3754153 is an older part number than the 3836710. However, that's not the case here. The 3836710 is quite a bit older.

[Scott S.]

Re: C@ SBC Exhaust Man.

Dave-----

It's possible that the GM #3836710 was the original part number for the washers. That's an old part number dating back to about 1955.

It's also very possible that it continued to be used in PRODUCTION after it was replaced for SERVICE by the 3754153.

Based upon "rule-of-thumb" part number sequence, it would seem that the 3754153 is an older part number than the 3836710. However, that's not the case here. The 3836710 is quite a bit older.

Joe,

Assuming the measurement for GM # 3836710 WASHER (11/32" ID x 11/16" OD x 1/8" thick) listed in Dave's P&A is correct, the 11/32" ID would be a pretty tight squeeze for the 3/8-16 x 2-1/4" outer exh. mfld. bolts, wouldn't it?

[Joe L.]

Re: C@ SBC Exhaust Man.

Joe,

Assuming the measurement for GM # 3836710 WASHER (11/32" ID x 11/16" OD x 1/8" thick) listed in Dave's P&A is correct, the 11/32" ID would be a pretty tight squeeze for the 3/8-16 x 2-1/4" outer exh. mfld. bolts, wouldn't it?

Scott------


Yes, I had not considered that. At 11/32" ID it would not work, at all, for a 3/8" bolt.

[David L.]

Re: C@ SBC Exhaust Man.

I agree, 11/32" = 0.344" while 3/8" = 0.375", so the 3/8" bolts would obviously not fit through the 11/32" I.D. washer.
Both my 1963 and 1964 Chev. Parts Catalogs (Oct. 62 & Oct. 63) list the 3836710 washer (11/32" I.D.) for 55-63 ALL, CORVETTE (8 cyl.) in Gr. 3.275 while my 1965 Chev. Parts Catalog (Oct. 64) lists the 3754153 washer (13/32" I.D.) for the same models. Note that the 64 & 65 models are NOT included in the 65 parts catalog for the 3754153 washer.

The I.D. dimension of the 3836710 washer in the 63 & 64 parts catalogs was apparently listed wrong. My 1957 Chevrolet parts catalog lists washer # 3836710 as 13/32" I.D. X 11/16" O.D. X 1/8" in Gr. 3.276.

As we all know the Chevrolet parts catalogs are a very good reference but they are not perfect.

Dave