Inline 8 rear exhaust manifold stud? Looking for photo.

I have a noticeable exhaust leak at the rear exhaust port, closest to the firewall, on my 248; probably a good 1/8" gap. Upon inspection I can see that prior owners were using the full one piece gasket that incorporates the intake and exhaust manifolds. I know there's been debate on whether to use this or not as the Shop Manual calls only for a gasket with the intake manifold. Putting that issue aside for now, what does the rear stud/clamp/washer/nut set-up supposed to look like? I think I'm missing the clamp, washer, and nut...hence the most likely cause of the leak. What I can see is what looks like a stud with a slot in it, like a giant flathead screw slot... I haven't gotten into pulling this apart yet as I've been working on a bunch of other projects. Front most stud uses a circular washer and nut. Other studs use a hexagonal "clamp" washer type thing with a nut. And, if I remember correctly towards the back of the engine, there is an almost rectangular clamp type thing that ties the intake and exhaust together and holds to head as well; it seems to uses the same nut as in other locations.

Here's what the Parts Manual is referencing for parts...seems like most of which I have, except for maybe the furthest one back.

Clamp, Manifold

1322890 x 7

212076 x 1 used at front of manifold

1306891 x 1 used at rear of manifold THIS IS THE ONE I'M REALLY QUESTIONING

Stud, Intake and Exhaust Manifold Clamp

1324182 x 7

1324183 x 1 Front End

1324184 x 1 Rear End THIS IS THE ONE I'M REALLY QUESTIONING

Washer, Manifold Clamp Stud and Bolt

202587 x 2 Front and Rear I THINK I'M MISSING THIS REAR ONE

Nut, Intake and Exhaust Manifold to Cylinder Head

1324591 x 9 AGAIN, I THINK I'M MISSING ONE OF THESE FOR THE REAR-MOST

Pin, Exhaust Manifold to Cylinder Heat Dowel? (NOT SURE WHERE THIS IS...or if it relates to this issue)

1321397 x 1 At rear and center hole

1342820 x 2 Pin, dowel (Exhaust manifold to cylinder head)

I've looked for photos online, but most show from the front of the engine or straight on sideview, or a non-stock set-up. The rear stud is up pretty close to the firewall so isn't shown many times.

Any thoughts, or known links to this type of discussion prior on the forum?

I can only comment on the Special engines. The later engines didn't have a bolt at the end of the exhaust manifold, just a stud with a slot like you mention.

I can only guess that Buick did this because of problems of exhaust manifold breakage when the long manifold tried to expand or contract in heating and cooling.

Well, it's good to confirm that I just don't have some backyard mechanic stud/what-have-you jammed in there!

Now, is this slotted stud supposed to have anything on the end of it, like the prescribed "clamp", washer and/or nut? The PM lists these components. I couldn't see in there all that well, but maybe the stud, though slotted, is threaded on the end. Without them, it seems like there'd be no way to close this gap on that one exhaust port other than maybe with the nut that is on the stud to the left-side of this port.

I plan on, when I have time and a few more soakings with PB Blaster, to loosen all of the exhaust and intake manifold nuts and tightening from the center out using the torque spec of 25-30 ft/lbs. That may close it up a little better too. All other ports are sealed up pretty good. Only that rear one visibly leaks exhaust especially when the engine is first fired up and it's burning some oil.

My Special and Super have the dowels. Came that way.

You may or may not stop the leak. Chances are pretty certain that the exhaust manifold is warped, twisted and/or bowed. Most are. The two end ports on mine did not even line up with the head ports.

Ben

Hmmm... There's got to be a way NOT to gas myself and the passengers while not moving then. LOL Well, I'll play around with it and see what I can do. Not a show stopper, but one more things on the list to someday figure out.

Be careful tightening those! On my '52 there is a SPECIFIC process for tightening all of the manifold fasteners. It involves taking the entire assembly apart and tightening everything in a sequence. It says if you don't do it that way you could crack the manifolds. I think it specifically mentions that you should not just go in there and tighten certain fasteners. You might want to bite the bullet and take the whole thing apart so you can replace all the gaskets. I went with new studs, nuts, and pilot rings too. I sealed the valve body with fireplace cement. It's all on my thread somewhere. I was never so nervous as I was while I was taking those manifolds off. I was just waiting for something to break! As my Dad always says, "I was so nervous you couldn't have gotten a pin up my a-- with a jackhammer.":eek:It all worked out fine though. I soaked everything in a 50/50 mix of ATF and acetone for several days before the job. I used heat on the studs too. Nothing broke! Keep us updated and good luck.

More good food for thought.

I think the process is the same on the '50 as well. I know it mentions to work on attaching the Exhaust Manifold Valve first (it's not like mine works anyway, LOL), adding the Intake Manifold, and then mounting all of it as a unit to the Cylinder Head.

I'll go back thru your build-up blog to see if you had any pics of what I'm looking for. Still unsure of what rearmost mount is supposed to look like when correct. As per Ben's notes, the exhaust manifold may be warped anyway. Weird how all other ports would mate up pretty well and have a gap only on this one...

Probably won't get to it this weekend; Sat's booked up with family stuff and my daily driver '07 Lucerne will probably get a brake job on Sun. The Lucerne also threw a P0411 code a while back so hoping to get the Secondary Air Pump changed soon too. Inspection is due end of the month and will not pass Mass. smog check with the Check Engine Light on.

Post #197 has some photos of that area:

http://forums.aaca.org/f163/rescue-me-51-41d-356199-8.html

Mine has no stud on the most forward or most rear holes in the head. Yes, the manifold is slotted as though a stud and clamp washer could be there, but as others said, the factory probably found that just cracked more manifolds...

There is a gap because the gasket is missing. Don't try to tighten it out or it probably will crack.

Here are photos of the areas in question from my '49. The front should have a stud. The rearmost slotted "stud" is a locator pin. It's not supposed to have a nut. The profile of the manifold there is sloped, so a nut and washer could not work anyway. The 2nd stud from the rear has a large plate that distributes the holding force over the center of the rear exhaust port.

Eric/Wheelnut. You guys have definitely ease my mind! Wheelnut's pics show exactly what I have. Same "pimpling" on the exhaust header as well. LOL I'll be leaving mine alone for now, but had already purchased a new copper gasket set a while back. I'll try to figure it out when those gaskets go on.

Eric, I also see that just like myself and Shadetree, you got to work the whole Fuel Pump suction hose project. That one's real fun with a full tank of gas that wants to run damn near continuously down your arms and all over the driveway...NOT!! The one I got from CARS had the right fittings, but not long enough. As it was about 1/2"-3/4" too short, I managed to mangle the threads on one of the hose fittings and cross-threaded it in the process of trying to put it on. Spent the better part of yesterday with gas running down both arms to still have not fixed it by the end of the day! Grrr!! I went to a local auto parts vendor this morning (in my area they're all closed on Sunday's) and bought a new longer length of 1/4" fuel line and a 5/16 thread hydraulic hose fitting. Cut the good fitting out of the CARS hose, stuck in the new length of hose and will modify the hydraulic coupling a bit when I get home. I hate being stuck at work when I know my car is probably sitting there dripping go-go juice slowly into a pan filled with absorbent.

The brake job on the Lucerne went rather well however; no more pulsing coming down from highway speeds. One small victory I guess.