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Manifold Bolt Missing??


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My Dad pointed this out to me a while back and I jumped on the internet and browsed through a few random pictures of straight eight engines. I couldn't find one that had a bolt in this hole so I figured it was like that from the factory. Granted, I only looked at maybe 2 or 3 pictures before I made that decision. Fast forward to now, and I've developed a pretty big exhaust leak at this location. So, I did some more in depth picture searching and I have found some engines that DO have a bolt in this location and quite a few more that don't. So what's the deal here? Is this hole supposed to have a bolt in it or not?

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I guess it's possible. It wasn't done by us. There is a hole there that you can put your finger in but I don't know if the remains of a stud are in there or not. The hole is full of crud. I'll have to investigate further. Thanks Aaron.

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There should be a stud in that location. The thread in the block is 3/8 inch course thread. The other end of the stud is fine thread. You will also need a cupped washer, large side toward the manifold and a 3/8 fine thread nut. The stud and nut you can purchase from a good parts store or a hardware store. The cupped nut will be harder to find. Torque this an all the others to about 28-30 foot pounds.

This stud is often missing on straight eights and I suspect that the stud may have broken off during servicing some other part or the expansion of the exhaust manifold exerted a sideways force on this stud and cracked or broke it. This last explanation is hard to believe given the relatively large opening for the stud at this location on the exhaust manifold.

Good luck.

Joe, BCA 33493

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Ok, guys, I have two '50s. Neither one has a bolt or stud at this location. Only a short 1/2 inch guide "nub". Same with the back of the manifold. The Super looks to have never had the manifold removed as there are no manifold to head gaskets, as per the shop manual. Therefore I believe there is supposed to be no bolt or stud in this position.

Ben

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First Born:

The rear of the manifold does not have a stud as you note as there is not supposed to be one there. Look closely and you will see that there is a stud at the next location forward and a curved large and thick keeper with a hole for this stud and the keeper spans the last two exhaust manifold ports. The stud at this location is longer than the others.

In your case, who knows if the factory just left it off or there is another explanation. I see many straight eights without the front stud.

Joe, BCA 33493

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Shadetree:

Do not use a bolt as it is not correct and is more problematic if you need to remove the manifold in the future. If the bolt will not come loose in the future, you run the risk of snapping the head off the bolt or breaking the bolt where the threads begin near the cylinder head. With a stud you may have to wrestle with the nut but your chances are better that the stud may break at or near the nut leaving you with the remainder of the stud to try a vice grip or other approach. In addition, with a bolt you may get one too short and in that case only a few threads will hold it when you torque it down or you may get one too long and it will bottom out in the head but not tighten the manifold securely.

On my 1953 Special, the front stud was broken off near the cylinder head but it was easy to remove with a lefthanded drill.

Good luck.

Joe, BCA 33493

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Thanks for the information guys. I don't know what the deal is with that stud location. Maybe there is some kind of stress related defect or warpage that occurs in these straight eights that causes that stud to break or even work itself out of the hole. If you look at straight eight pictures on google, most engines don't have them. But there are some that do. Even among our small group here some have them and some don't. Very interesting. Ben, I don't believe my manifold has ever been off either but at the same time, you have to wonder why the factory would put a threaded hole there if it wasn't meant to be used. I just looked at the CARS site and found a listing for manifold studs. It says there are supposed to be 11 studs per engine. I don't have a clear enough picture of my engine at hand right now to count the stud locations (I'm at work) but doing so later should solve our little quandary. Here are the links for the stud AND the nut listings.

Old Buick Parts - CARS. Inc.

Old Buick Parts - CARS. Inc.

EDIT

I just looked at the listing on CARS for the stud nut. In the description it says 9 per engine. So does that mean 9 studs receive nuts and the two on either end just have empty studs there? That would corroborate Ben's comment about those being "guide nubs".

Edited by shadetree77 (see edit history)
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My Dad pointed this out to me a while back and I jumped on the internet and browsed through a few random pictures of straight eight engines. I couldn't find one that had a bolt in this hole so I figured it was like that from the factory. Granted, I only looked at maybe 2 or 3 pictures before I made that decision. Fast forward to now, and I've developed a pretty big exhaust leak at this location. So, I did some more in depth picture searching and I have found some engines that DO have a bolt in this location and quite a few more that don't. So what's the deal here? Is this hole supposed to have a bolt in it or not?

FWIW

The attached pics are taken from a 1928-1954 MASTER CHASSIS PARTS BOOK . . . . .

Pic #1 is labeled as a 1953 Series 40 engine . . . . . last year for Buick's Straight Eight engine. The pic definitely shows a bolt and washer or a stud, washer, and nut at the very front of the exhaust manifold.

Pic #2 shows differences in quantities or sizes for 1946 thru 1952, Series 40 & 50 smaller engines from 1946 thru 1952 Series 70 and the 1953 Series 40 larger engines, intake and exhaust manifold clamp studs, washers, and nuts. This might be the reason for conflicting posts above. The exhaust manifold to cylinder head dowel pin has a separate listing.

You might have been looking/comparing smaller and larger engines if there is a difference in quantities or if all the studs missing were busted off :(. Just my $02 worth. I might be wrong.

Al Mack

BCA #8965

"500 Miles West of Flint"

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Edited by 1953mack
clarification (see edit history)
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Mine is broken off on my 51 super. I for sure see a broken stud inside. Actually both end studs appear to be broken off. My guess is that is why my manifold cracked... as the lack of support allows the expanding manifold to bend in ways it should not.

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I vote for the bolt (stud). A picture from my 49.[ATTACH=CONFIG]145579[/ATTACH]

looking close at this pic I notice this nut and retainer in the front posision do not look like the others. At least not the same material they look like they are corroding differently and the retainer looks more round than the others. Just an observation, maybe yours was once broken as well.

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looking close at this pic I notice this nut and retainer in the front posision do not look like the others. At least not the same material they look like they are corroding differently and the retainer looks more round than the others. Just an observation, maybe yours was once broken as well.

The end retainer is different from those that span the intake and exhaust ports. But it fits the cast recess perfectly. This photo is from a series I took prior to starting the restoration. I was able to remove the intake and exhaust manifolds without breaking off any of the studs, including the one under discussion. It was rusted more than the others and due to its length it is subjected to greater stress when it is removed. I used lots of Kroil on all these studs for a week before I took them out and then applied lots of heat to any that seemed reluctant to come out. My opinion is that this long stud is a weak spot in the fastener design on the straight 8 manifolds and for those that find it missing, it has been broken off earlier in the car's life rather than missing by design. ($0.02)

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Chevy-Dude:

There is supposed to be a stud in the front for the first exhaust port. Your broken stud is probably not that deep and it is in a position to make extraction easy.

Let me correct my previous post in regard to the rearmost stud. It is longer than the rest and fits between the rear exhaust port and the rearmost intake port and along with a keeper it seals both the rear intake port (for cylinders 7 and 8) and the rearmost exhaust port (for cylinder 8). There is no stud for the very end of the exhaust manifold, at least on the 248 and 263 engines.

Joe, BCA 33493

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Chevy-Dude:

There is supposed to be a stud in the front for the first exhaust port. Your broken stud is probably not that deep and it is in a position to make extraction easy.

Let me correct my previous post in regard to the rearmost stud. It is longer than the rest and fits between the rear exhaust port and the rearmost intake port and along with a keeper it seals both the rear intake port (for cylinders 7 and 8) and the rearmost exhaust port (for cylinder 8). There is no stud for the very end of the exhaust manifold, at least on the 248 and 263 engines.

Joe, BCA 33493

Thanks for the reply, So lots of kroil and heat huh? I am about to remove mine but am very reluctant. Unfortunately for me my stud is broken off inside the head too far for vice grips.... and I havent looked too deep into the rear one missing but do plan or replacing them all. Is there a place that sells replacements?

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Good photos.......just trying to remember.....how many rings (not sure what they should be called) fit into the head......there is a recess in the head to accept them

Above photos seem to indicate 4 but I thought there were more. Is there purpose to seal or just to help locate the manifold?

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