Small block exhaust manifold spacer washers, Black phos or Cad?

[Jim S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

I think the spacer/washer was natural, unplated.

I've never found a part number for that washer but I have several near new ones in my misc bolt/nut box that were removed from brand new cars back in the 60's.

Mike ,

Try 4542461. I wrote it down a while back , and I think this is the number I wrote that goes to that washer . I think?

Jim

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Scott,

Here is an exception on my 67 327/300 June 29 67. No spacer washers at all, as well as no french locks. Whether it was a late production change in 67, or some production experiment, my original engine came with special exhaust manifold bolts with an intergral washer head and self locking threads which obviated the use of french locks.

On the one I removed, it has the remnants of black phosphate among the rust. Here's a few pictures:

From previous threads on the subject, I am not the only one with this anomoly on a 67 S/B 300, but I think most were very late production.

Jerry, thanks very much for posting and for the pictures too, I just looked up your old Thread about this from 2006, very interesting (pictures are gone though).

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

I think the spacer/washer was natural, unplated.

I've never found a part number for that washer but I have several near new ones in my misc bolt/nut box that were removed from brand new cars back in the 60's.

Michael (and everyone),

I may have found some more information on this washer. The same parts group for manifold bolts (3.275) also includes the following (1967 P&A):
55-63 ALL, CORVETTE (8 cyl.) ....... WASHER. intake and exh. (11/32 I.D. x 3/4 O.D. x 1/8 thick) ....... 3754153 (A.R., ref. Gr. 5.383)

I don't know why it is listed this way, "55-63" ALL, Corvette". Does this mean the Washer is for ALL 8 cyl. Chevrolets from 55-63 and ALL Corvettes up through the catalog print date (Oct. '66)?

This same washer is listed for the idler pulley for a 1963 Passenger car, 409, exc. P/S (quantity 2).

This same washer is then listed in Group 9.173:
9.173 BOLT-WASHER, Air Conditioning Compressor Mounting Attaching Parts
ALL ALL ........................... WASHER, bracket support ................. 3754153 .... 1 .... (5.383)


Finally, this washer is listed in the Standard Parts section of the same P&A book, with a slightly different O.D.
Group 8.929, Flat Washers.
3754153 ....... 3/8" x 3/4" x 1/8" ....... (Cadmium) ....... (5.383)


I found this washer called out by part number once in the 1967 AIM, UPC 7-C2, Item 17, 3754153. The Revision Record shows that this Washer was added 7-21-66.

[Michael H.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Thanks Scott. That does sound a lot like the correct manifold bolt washer. It would have to be 13/32" ID, and if it is, that would come close to being correct. The O.D. is a bit larger than the .700" that John Hinckley measured on an original but it's close. He measured .735" OD.

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Michael,

I was so involved with tracking down the leads that I didn't see the forest for the trees (forgot to do the conversions, 3/8" being larger than 11/32" I.D. )

I tried to look up the part number Jim posted (4542461), but no luck. It just doesn't seem right that a part used on so many cars has an unknown part number. I have another lead that I will try to track down tomorrow.

[Michael H.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Michael,

I was so involved with tracking down the leads that I didn't see the forest for the trees (forgot to do the conversions, 3/8" being larger than 11/32" I.D. )

I tried to look up the part number Jim posted (4542461), but no luck. It just doesn't seem right that a part used on so many cars has an unknown part number. I have another lead that I will try to track down tomorrow.

Steve,

It's strange that one source calls it 11/32" and another shows 3/8". If it were to be used with a 3/8" bolt, I would guess that the I.D. would probably be closer to 13/32". The washer that John Hinckley measured was .400", or about 13/32".

I'm not 100% sure but I think I ordered several of the 3754153 washers decades ago and the ID was too small for the 3/8" exhaust manifold bolts.

I'll see if they're around here, if I still have them.

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

It's strange that one source calls it 11/32" and another shows 3/8". If it were to be used with a 3/8" bolt, I would guess that the I.D. would probably be closer to 13/32". The washer that John Hinckley measured was .400", or about 13/32".

It seems even more odd that both dimensions were found in the same 1967 P&A, just different sections. The 3/8" ID dimension was located in the "Standard Parts Section" of the '67 P&A (Group 8.929), and the 11/32" ID dimension was listed in several other sections of the '67 P&A.

[Joe L.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

All------


Attached are photos of an NOS GM #3754153. This is the washer that GM says was used for the small block exhaust manifold bolts. This washer has the following measured dimensions:

OD= 0.735"

ID= 0.40"

thickness= 0.135"

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Thank you Joe, very much appreciated!

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Update: Found the drawing for 3754153 Washer in Adams, p. 394. This same washer is used for the Clutch Rod (UPC 7-C2, Item 17). Cad or zinc finish called for.

[Michael H.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Update: Found the drawing for 3754153 Washer in Adams, p. 394. This same washer is used for the Clutch Rod (UPC 7-C2, Item 17). Cad or zinc finish called for.

I have some of those here, somewhere. I ordered several in the 70's thinking they would also be the exhaust manifold washer but I thought something was different than originals for the manifolds??? I don't remember what it was though.

[Rich P.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Clutch push rod spacers are thicker and have a smaller opening.

[Michael H.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Clutch push rod spacers are thicker and have a smaller opening.

That sounds right. Wasn't the clutch push rod pin/washer closer to 5/16"? That would be too small for a 3/8" exhaust manifold bolt.

[Scott S.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

Clutch push rod spacers are thicker and have a smaller opening.

Hi Rich,

The drawing in Adams' book has " '67 Clutch Rod" written on the drawing itself, the caption (part of a longer caption above the previous drawing) says Washer 3754153 at the clutch rod location was new for '67 ("1967 only").

[Rich P.]

Re: Small block exhaust manifold spacer washers, Black phos or Cad?

They are definitly different from 63 to at least 72. Spacer is thicker and the opening definitly smaller. (Like Mike said around 5/16)