68 BB Exh Washers / Joe?

[Tom B.]

If you're tuned in Joe:

Welcome back, I had a "sticky note" to remind myself to revisit a question. It had to do with 68 big block exhaust manifold washers. (You'll have to visit the archives to fill in the blanks). It was originally posted by chester but I need the info too. Question: were they used or not? Variety of info given: yes, no, on the ends, etc. Chester decided yes, but I think the jury was still out. I still have a new pack of these washers that I'm not sure what to do with. Can you shed some light? Thanks in advance. Tom #24014

[Gene M.]

Re: 68 BB Exh Washers

Tom

The big block bolts for the exhaust manifolds have a bearing washer face as part of the bolt. It is one piece. No seperate washers were used on big blocks. Washers are only on small blocks. Different manufacturers are found on originals. There is one type that does not have the previous mentioned bearing face. Sorry I don't remember the head marking.

[Gene M.]

Re: 68 BB Exh Washers

Tom

The big block bolts for the exhaust manifolds have a bearing washer face as part of the bolt. It is one piece. No seperate washers were used on big blocks. Washers are only on small blocks. Different manufacturers are found on originals. There is one type that does not have the previous mentioned bearing face. Sorry I don't remember the head marking.

[Tom B.]

Re: 68 BB Exh Washers

Thanks Gene. I have a mixture of "correct" bolts from what the 68-69 TM says for 68 BB exhaust manifold fastners, and that includes four or five of the (3rd variety) Mark IV bolt with built in washer equipped recessed hex head. That's the same as what you mentioned. I guess I was trying just keep what I have but what the hell, after all this I might as well find a few more of the built in washer type. Thanks again. Tom #24014

[Tom B.]

Re: 68 BB Exh Washers

Thanks Gene. I have a mixture of "correct" bolts from what the 68-69 TM says for 68 BB exhaust manifold fastners, and that includes four or five of the (3rd variety) Mark IV bolt with built in washer equipped recessed hex head. That's the same as what you mentioned. I guess I was trying just keep what I have but what the hell, after all this I might as well find a few more of the built in washer type. Thanks again. Tom #24014

[Joe L.]

Re: 68 BB Exh Washers / Joe?

Tom-----

You know, the more research I do on the subject of these BB exhaust manifold bolts, the LESS I seem to know. Here's what I think I've found for model years 67-74; I haven't been able to come up with anything yet for 65-66:

1967-69 427s may have used bolt GM #3909821 at all locations. This bolt is 3/8-16 X 1-3/16". It is a standard, non-flanged, hex head bolt. For 1967, I believe that french locks were used on the 2 end bolts, but this practice was probably discontinued afterwards.

For 1970-74 454s, I believe that bolt GM #3909821 was used on the end locations, with bolt GM #3736035 used at all other locations. The #3736035 bolt is 3/8-16 X 1-1/4".

Now, none of this answers your question about the washers. I used to think that I knew the answers on this one, but, quite frankly, now I'm not so sure. I'll need to research it more.

[Joe L.]

Re: 68 BB Exh Washers / Joe?

Tom-----

You know, the more research I do on the subject of these BB exhaust manifold bolts, the LESS I seem to know. Here's what I think I've found for model years 67-74; I haven't been able to come up with anything yet for 65-66:

1967-69 427s may have used bolt GM #3909821 at all locations. This bolt is 3/8-16 X 1-3/16". It is a standard, non-flanged, hex head bolt. For 1967, I believe that french locks were used on the 2 end bolts, but this practice was probably discontinued afterwards.

For 1970-74 454s, I believe that bolt GM #3909821 was used on the end locations, with bolt GM #3736035 used at all other locations. The #3736035 bolt is 3/8-16 X 1-1/4".

Now, none of this answers your question about the washers. I used to think that I knew the answers on this one, but, quite frankly, now I'm not so sure. I'll need to research it more.

[Tom B.]

Re: 68 BB Exh Washers / Joe?

Thanks Joe. I just don't think I'd have as much fun if all this was so simple. I have no place else to look. One of these days if you find something on the washers I think there's more than one or two of us that would like to know. Thanks again. Tom #24014

[Tom B.]

Re: 68 BB Exh Washers / Joe?

Thanks Joe. I just don't think I'd have as much fun if all this was so simple. I have no place else to look. One of these days if you find something on the washers I think there's more than one or two of us that would like to know. Thanks again. Tom #24014

[Rolf Krueger]

Re: 68 BB Exh Washers / Joe?

1. On 1965-1969 Big Block engines, Grade 8 hex head bolts were used at all eight positions of the exhaust manifold. These bolts were black oxide plated. At the engine plant, washers were not called out for use under these bolts.

2. On 1970-1974 Big Block engines the same hex head bolts described above were used on the four inboard postions only. On the four outboard positions, a flange head hex bolt was used. This change was made to reduce the incidence of cracking of the outboard mounting ears of the exhaust manifolds. Again, at the engine plant, washers were not called out for use under any of these bolts.

3. At St. Louis, for cars equipped with power steering and/or air conditioning, some of these engine plant installed exhaust manifold bolts were removed and replaced with studs or longer bolts. The studs and longer bolts were used to mount the brackets for those accessories. Washers WERE called out and used under the St. Louis installed exhaust manifold studs and bolts.

[Rolf Krueger]

Re: 68 BB Exh Washers / Joe?

1. On 1965-1969 Big Block engines, Grade 8 hex head bolts were used at all eight positions of the exhaust manifold. These bolts were black oxide plated. At the engine plant, washers were not called out for use under these bolts.

2. On 1970-1974 Big Block engines the same hex head bolts described above were used on the four inboard postions only. On the four outboard positions, a flange head hex bolt was used. This change was made to reduce the incidence of cracking of the outboard mounting ears of the exhaust manifolds. Again, at the engine plant, washers were not called out for use under any of these bolts.

3. At St. Louis, for cars equipped with power steering and/or air conditioning, some of these engine plant installed exhaust manifold bolts were removed and replaced with studs or longer bolts. The studs and longer bolts were used to mount the brackets for those accessories. Washers WERE called out and used under the St. Louis installed exhaust manifold studs and bolts.

[Tom B.]

Re: 68 BB Exh Washers / Joe?

Rolf,

Much thanks for the additional information. With all the input I was trying to "hold" a couple temporary conclusions (to be adjusted with new/additional/correct info):

1) that 68 BB exhaust manifold fastner washers were not called for.

and (I may need to adjust this one):

2) That built-in washer hex head bolts were ONE variety of 68 exhaust manifold fastner and were more than likely used (when used) on the four outboard positions.

I found your additional info of the black oxide plating to be interesting. I didn't see mention of it before and it is probably obvious and common knowledge to most others. With that, I had to re-observe mine and they are, which appear as said, black oxide plated.

You and Joe have both NOT mentioned the built-in washer hex head bolt (flange hex head bolt) as correct for the 68 BB exhaust manifold application. The reason I still ask is that the 68-69 TM mentions it, as have others in postings, and I have a few on my 68. Is there still any chance that it may have entered it's application in 68? Any additional information would be great, Rolf. Thanks again. Tom #24014

[Tom B.]

Re: 68 BB Exh Washers / Joe?

Rolf,

Much thanks for the additional information. With all the input I was trying to "hold" a couple temporary conclusions (to be adjusted with new/additional/correct info):

1) that 68 BB exhaust manifold fastner washers were not called for.

and (I may need to adjust this one):

2) That built-in washer hex head bolts were ONE variety of 68 exhaust manifold fastner and were more than likely used (when used) on the four outboard positions.

I found your additional info of the black oxide plating to be interesting. I didn't see mention of it before and it is probably obvious and common knowledge to most others. With that, I had to re-observe mine and they are, which appear as said, black oxide plated.

You and Joe have both NOT mentioned the built-in washer hex head bolt (flange hex head bolt) as correct for the 68 BB exhaust manifold application. The reason I still ask is that the 68-69 TM mentions it, as have others in postings, and I have a few on my 68. Is there still any chance that it may have entered it's application in 68? Any additional information would be great, Rolf. Thanks again. Tom #24014

[Chuck G.]

Re: 68 BB Exh Washers / Joe?

Hi Tom. Here's my "two cents worth". I went round and round with this a few months ago---end result----I used the washer head bolts on ALL positions on my exhaust manifolds (69 427). The Paragon repro non washer head bolts bottomed out in the thread bore before they tightened against the manifold if you did not use a washer. The black oxide washer head bolts are still available from GM as are the non washer head style. (thanks Joe Lucia!!). Since the TM called for either, I elected to use the washer head style everywhere, as I felt that they would hold better and be less likely to gouge or even break the manifold "ears". As I recall, they were also a bit shorter. Chuck

[Chuck G.]

Re: 68 BB Exh Washers / Joe?

Hi Tom. Here's my "two cents worth". I went round and round with this a few months ago---end result----I used the washer head bolts on ALL positions on my exhaust manifolds (69 427). The Paragon repro non washer head bolts bottomed out in the thread bore before they tightened against the manifold if you did not use a washer. The black oxide washer head bolts are still available from GM as are the non washer head style. (thanks Joe Lucia!!). Since the TM called for either, I elected to use the washer head style everywhere, as I felt that they would hold better and be less likely to gouge or even break the manifold "ears". As I recall, they were also a bit shorter. Chuck