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47 super exhaust manifold


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Its That time of year again, got to replace the exhaust /intake gasket again, seems like I do it every spring, when it expands and contracts the gasket wrinkles and it starts to leak. The exhaust manifold is a repop, not oem.

I've tried everything and it still does it, this year I think I may just try a slurry of graphite and oil , am wondering if anyone has done this and how well it worked.

Don

1947 56C

Edited by sledheader48381
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I finally gave in and did it. I cut the gaskets and used just the intake gaskets. I had the machine shop cut the intake manifold a bit more so I could run the gasket, and I had them open up the bolt holes in the valve body and intake so I had a little more adjustment between the two manifolds. I used High Temp RTV on all of the gaskets between the valve body and manifolds. Graphite and oil between the exhaust manifold and head... It's pretty quiet now, but I don't have my hopes up. I really wish they would have split the manifold from the factory...I really think it's just too long of a manifold...warps too easily, moves around too much.

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I am having the same problem with my '50. BUT THIS WAS NOT A PROBLEM 50 years ago. I have only driven 1700 miles or so since replacing mine. Not bad yet, but I can hear the whicker, whicker, whicker,. Just now, reviewing the instructions in the shop manual, it says" Exaust manifold gaskets are not used', . Spoke with a brother , and we both think we remember intake gaskets that were round flat discs, similiar material as the thin head gasket used on dynaflow equipped engines. Sure wish my memory was better.

Ben

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Ummmm? This is just an idea, but, what if you cut a gasket out of brass sheet stock? On the old Japanese two-stroke motorcycles the head gaskets were made out of brass: what about aluminum? I know that the modern gasket material blows apart because it's made from fibers.

Just wondering,

Jaybird

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The original manifold assembly used 4 pilot rings to locate the intake manifold correctly to the cylinder head intake ports. There were four very thin steel flat washers or gaskets that slipped over the pilot rings. These had an outside diameter to cover the intake manifold port and the cylinder head intake ports. They had a circular raised area that got crushed flat when the manifold studs were torqued to the shop manual specifications. The exhaust manifold mated to the cylinder head without a gasket, just a painted on mixture of motor oil and graphite. The shop manual procedure says to assemble the intake, exhaust and hot box together with the appropriate gaskets and snug them up. Install on the engine and torque studs to near the final specification. Then tighten the bolts holding the manifolds and hot box together. Go back and re-torque the manifold to cylinder head studs. There were octagon shaped keepers under the nuts on the manifold to head studs. The front stud used a dished washer under the nut.

I have had my assembly to a machine shop to have the manifold surfaces planed flat. I then used the copper gasket set and used oil and graphite between the manifolds and cylinder head. I have had to re-torque the studs several times because the gaskets do flatten a bit.

One final note concerns the shop manual torque specifications. These are probably based on the standard torque specs for 3/8 studs and the fact that there are really no regular gaskets used. I found good results with the copper gaskets by exceeding the maximum torque on the studs to 32 ft/lb over the recommended 30 ft/lb.

If I had to do it all over again, I would do without the gaskets and just use the intake gaskets and oil and graphite.

Joe, BCA 33493

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Don, what does "style" mean? What were the originals made of?!?!?!? and the new ones?!?!?! I only ask because the REAL-OEM's may have been made with asbestos. I'd hate for you to go through the same exact problem happening again...

Just a thought,

Jaybird

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All; Got my gaskets and they are just as Ben and Joe said, small steel rings that go around the intake ports, they have a raised area that will crush when the manifold is bolted up.

The gaskets are new old stock Victors with the Buick and Victor part# on the package.

Was wrong on the name of the company,it's

N.B.Pease & Co.

43 Foundry St.

Palmer Mass. 01069

413-283-7620

I'm planning on doing the repair over memorial weekend, will report how it went after.

Don

47 56C

Edited by sledheader48381
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Don, good for you--REALLY! I was just trying to keep you from using too many swear words a year from now: at times you get something modeled after the original but made with something other than what was used on original.

Jaybird

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  • 1 month later...

all; Finally got around to doing my manifold and unfortunetly it didnt work the intake rings sealed great but the graphite slurrey did'nt seal the exhaust manifold. Back to square one I just can' help but feeling my problem involves the aftermarket manifold I bought, has onyone bought one from Bobs? any problems? at wits end.

Don

47 56 C

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  • 2 weeks later...

Hi Don,

We put my 47 manifold on a mill to correct any imperfections, all joints machined to fit. Then following manual instruction, put her together. Has been quiet at least since you were here last.

Oh yeh, we did use an exhaust gasket coated with copper sealer to permit it to slide. The oil and graphite just doesn't cut it.

Cliff

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  • 1 month later...

To all; finally had the time to, A repair,and B reply As it turns out as I suspected the manifold was the problem, when I first got it about 8 years ago I had it machined with the intake I took it to a machine shop again and it is warped. I decided to go back to my origional factory manifold that I had welded some years ago, So far so good.

One thing I did find out will tring to repair is ,there is now a process used to weld cast iron in which the part is heated to 600 degrees then welded with a special rod then cooled slowly after the repair I could not have this done on mine due to the previous repair but have second manifold with a crack that I might try if needed.

Thanks Don

47 56C

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  • 3 months later...

Hey ,Don,

How is the exhaust holding up??

I had to replace the exhaust and valve body on mine. I had the manifokd to head surfaces "cleaned up" to be sure it is true. Reassembled as per manual. No leak at valve body but ALL exhaust ports leaking badly from bottom of manifold. Really bummed out.

Ben

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  • 2 weeks later...

To all; Car is in storage for now, haven't driven it since Nov. but so far every thing seems to be working well.

I tried those copper clad gaskets on my car with no luck, but that was with rhe aftermarket manifold, it expanded and contracted so much the over the course of a season the gaskets would bunch up in between the exhaust and intake ports and eventually start to leak, but again that was with the aftermarket manifold.

Am wondering if any one out there has used an aftermarket manifold with better luck than me.

Don

1947 56C

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I replaced the manifold gasket on a 1947 Buick 320 ci a couple years ago. It, to, had previously had problems sealing and also suffered some exaust maniflod cracking. I welded up the center section of the exaust manifold using brazing rod with an big tiped oxygen, accetaline torch. Then assembled it all with a copper and filler gasket from Bobs. What I did different was to not tighten down any bolts holding the manifolds both together and to the head till I ran the engine and brought it up to temperture. I Then socked the bolts down tight to the expanded parts. The intake was sucking air making the engine run poor and the exaust leaked here and there but I was able to get it all up to running temp. After it was tightened it ran smoth and quiet and has ever since.

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I have been down the road with this problem for some time but I think I have it done for a while now. I bolted (snug) the intake, exhaust and the hot box together and took the assembly to a machine shop and had them smooth the surfaces where the intake and exhaust ports contact the cylinder head. Then I put a thin layer of FURNACE CEMENT on the triangle gasket and gasket from the hotbox to the intake and bolted these snug again. (There is a steel ring that goes between the hotbox and the exhaust manifold where the triangle gasket sits) Loosened the exhaust pipe hanger on the side of the transmission so it could move a little. I put a new gasket where the hotbox bolts to the exhaust pipe, again with some furnace cement on this gasket. I mixed up some 50 weight oil and dry graphite to make a paste and applied to both sides of the copper clad gasket set. Installed new grade 8 studs of the correct length from a hardware store. I used the original keepers for the studs with some 50/graphite paste under these and then put a grade eight washer over each keeper and then a grade 8 nut on each.

With the help of a friend I installed the whole assembly to the cylinder head and tightened the nuts on the studs starting from the center and moving out to the ends. When I got to 30 lbs.-ft of torque I started tightening the bolts and nuts holding the intake, exhaust and hotbox together. Then I tightened

the exhaust pipe flange to the exhaust manifold outlet. Then tightened the exhaust pipe hanger.

I had to retorque these nuts every few weeks as the copper gaskets compress a bit. The whole thing finally quieted down at 32 lbs.-ft of torque on all but the very front nut that is about 30 lbs.-ft. Maximum torque on a 3/8 stud with course threads is about 30 lbs.-ft but you can go higher (35 or so) with a fine thread nut. The stud going into the cylinder head is course thread but it threads in an inch or more so I suppose I could go a little tighter but I don't need to at this point.

I think getting the intake and exhaust ports machined smooth and flat is really necessary when you are working with used parts.

Joe, BCA 33493

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