kookie1

'37 Pontiac 6 manifold torque question

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I'm about to install my cleaned and painted manifolds with new gaskets but the engine studs and nuts are original.   I'm wondering what torque values I should be using on the 3/8" nuts.   I've read all about plain steel bolts of pre-40s cars stretching due to over tightening.    If I'm following the recommended charts, is 28 ft. lbs. enough for manifolds and should I be using anti seize on the studs?   The charts specify 30-35 ft. lbs. and a 15 to 25% applied reduction in torque if anti-seize is used?    And is it a good idea to use a light coating of 'Copper Spray-a-Gasket Sealant' on the manifold gaskets before assembly?    Any suggestions would be appreciated.  Thanks

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Posted (edited)

Did you find the plate?

 

The only thing I would suggest is that you carefully check for expansion room. On any engine the manifolds move a little, mainly the exhaust. It gets much hotter than the exhaust ports in the block, which have water around them. In use, when the manifold gets bigger it slides on the gasket. How much varies. The longer the engine is the more of a problem it is. For instance, on v-8s some guys get away with ignoring it for a while. On the big Buick 320 straight eight, there are actually 2 expansion joints in the manifold!

 

Make sure that as the exhaust manifold gets longer that it wont "bottom out" on studs or bolts or whatever. Use whatever the factory did for washers if you have them. Don't use soft washers that will squish down and stop things from moving. If you have to wing it, at least use hardened washers, or cone washers with the small side of the cone to the nut or bolt head. Inspect closely for anything that would try to stop the expansion.

 

Make sure the manifold is flat before you put it on. Adjust intake/exhaust if necessary, machine it if it is warped.

 

Sorry I didn't really answer the question. I would probably use anti-sieze. There are not torque specs for my car, so I hadn't really considered that. Tighten from the inside to the outside and make a couple of passes like you would with any large item. If I used a torque wrench, I would probably use the specs from an early 50s Pontiac, after verifying that the threads are the same size.

 

Edited by Bloo (see edit history)

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Hi Bloo,

 

No, I didn't find a choke stove cover.    I called as well as emailed several people from the catalog images you sent me but no luck.   I finally decided to make my own thanks to John Hess for the ruler image and you for the straight-on image.   I used those pix to create a drawing/pattern in a Word document so I could reduce/enlarge the image to fit the measurements John gave me.   It worked pretty well.     I cut out a piece of 1/8" steel plate for a fixture to bend the 20 gauge sheet metal over.    That was necessary because of the manifold's raised cast iron bosses around the bolt holes that hold the cover in place.   I'm pretty happy about the way it turned out.   I had to use 5/16" bolts because I had to drill out the original 1/4" screws in the manifold that were totally rusted in place.

 

As far as the torque question goes, yes, the manifolds are already flat and even, no warping visible.   I've purchased grade 8, 1/8" thick washers as well.   They happened to be zinc plated which acts as a lubricant also when figuring torque values.    Are you aware of anyone using gasket sealant on the manifold gaskets before installation?    Any problems doing that?

 

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Wow! Nice job!

 

I don't know about the sealer. I probably wouldn't, and if i did, then only on the intake. I'll have to hang back on that one and see what others in here think.

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Thanks John and Bloo.    I want to keep the car as close to original as I can.   This will be the only piece that isn't original, well, original after my grandfather gave it up.   It's got a WA-1 carb from a '49-52 so I guess it isn't really, totally original but everything else is.    I guess I can live with that.    As they say, in this life we don't actually own anything, we're just custodians.

 

Hope some other guys with more experience than I have can chime in on this manifold sealer question this weekend.

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Hello,

Ive had the manifolds off my '51 and 53 a couple of times now over the years, mainly for valve lash checks and other times to replace the manifold stud set as the rear most one was broken on the 53. I machined a full set of studs to replace the originals as they have obviously seen a large number of thermal cycles over the years.  Replaced all the nuts with Brass manifold 3/8 UNF nuts specifically as  for 2 reasons: no antiseize required as being non-ferrous it wont corrode to the stud thread, 2- the brass thread will give up easier than the steel stud if for an unknown reason it does pickup over time. Also  replaced the flange gasket studs and used brass nuts at the same  time for the same reasons. Final torque values were 25 ft/lbs with No sealer on the manifold gasket. As the manifolds are not water cooled I could see no reason to apply the sealant and as such have used the same joint gasket numerous times now when doing routine maintenance on the 2 Chieftains. To torque the nuts especially  the difficult access ones I use a 1/2 universal socket ( ie one that has the unijoint built in to the socket) That's the only tool I can find to get an accurate grab on the nut to allow the torque value to be applied.

So far the fix has been ideal in that the manifolds are easy to remove as the nuts come off the studs readily , the manifolds haven't cracked so enough lateral movement on the studs to prevent stress and none of the new stud set has cracked or parted. The gasket comes off cleanly every time and as such I have re-used them on at least 2 occasions now after scheduled maintenance. Worked well for me.

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When I first got my car the manifold was warped. I replaced the gasket and used a sealant. It did help but not enough. I got it machined by a reputable shop but they kinda fumbled around with it. Ended up breaking off the choke tube from the exhaust. Not feeling 100% confident, I believe I still put a thin coat of Permatex Ultra Copper rated at 700F on both sides of the gasket around any ports in question. I like to think it helped. I personally wouldn't use it if I didn't feel the need to. I also drilled out the old choke tube broken in the manifold, rebent the existing tube to reach back into the manifold and sealed it with the Permatex. The sealer hasn't burnt, bubbled or melted. I also chose to use anti-seize on the bolts in case I had to remove the manifold again. I'm always under the hood double checking things and one of them are the manifold nuts. I usually find something that can be snugged up again. I also consider myself a human torque wrench....never owned one.  

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Hi Russ,

 

Thanks for taking the time to answer!    You"re just the guy I was hoping would respond, one who's done it on his own car.   You've done some serious work on that '53 and it's obvious you have some skills, machining your own studs.    Looks great!!

 

You answered my questions to a "T".    The manifolds are going back on without any Copper sealant use and 25 to 28 ft.lbs of torque is what I'll use.    And, as an added bonus, you unknowingly answered a question I had about those really hard to access manifold nuts.   It was tricky to get a wrench on them and make even an 1/8 degree rotation at a time.    I was wondering when I took them off how the heck I was going to get a torque wrench on them and to get an accurate reading as well.   Thanks for the idea of a 1/2 universal socket!    It'll make my time considerably easier!

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Hi Summershandy,

 

Man, you've had some problems with that engine!    After reading about peoples warping problems I went right out, back then, to check if mine were warped since I hadn't bothered to notice when I removed the manifolds.   Thankfully they weren't.    I'll use anti-seize also on the studs.    I snapped two bolts that were rusted solid trying to remove the heat riser so I'm really into using anti-sieze where ever it looks useful.    The brass screw in the heat riser housing that holds the counterweight spring support bracket (or whatever it's called) was also rusted in tight.   Fortunately, it was brass and easy to drill out and re-thread with a tap.    The broken bolts in the intake manifold were no fun to drill out and took quite a while to do trying not to ruin my manifold.   Luckily all turned out well.

 

Anyway, glad to hear you got your manifolds flat and level.    That alone can solve a ton of future problems.

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Looks nice Russ!   Wish my block looked that clean.    A quick question tho, what is that strap for that runs from #5 spark plug over the exhaust manifold, is pinned to the throttle linkage pin on the intake manifold and goes down to somewhere for some reason?   Was that original?    Don't think I've ever seen one like that before.

 

And one other question, what did you soak the carb in to clean it up like that?   I need to do that to mine one of these days.

 

 

Edited by kookie1
can't speel, I mean spell. (see edit history)

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Kookie, my guess before Russ replies is, must be throttle linkage for right hand drive cars.... saw the trans linkage in the other picture...  Which brings up my question .... Is a right hand drive manual transmission the same as left, just shift linkages out the other side ?..  John

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Oh yah, John, I should have noticed the steering wheel in the first pix.    That makes a ton of sense, duh!    I should have been more observant. 

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2 hours ago, kookie1 said:

I should have noticed the steering wheel in the first pix

Don't feel bad....I never noticed either! Interesting trying to wrap one's head around it......

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Also what's neat is I've got a tab like that on my intake where a bracket would go. On the bottom instead the top.  Guess it could be for the same set up?

 

 

 

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Hi Gents

Re the bracket next to # 5 plug as mentioned is for the throttle linkage as obviously we are on the opposite side to you guys over there. 

The gearcase  is not the same for Right hand as compared to  LH drive vehicles  as the linkages to connect the column shift rods  are on the opposite side. The internal cross shafts exit on the RH side of the gear case to suit the RH column linkages.
Bellhousing is also different as the clutch throwout fork etc are all Right handed where they exit the housing. 

For the carburettors -  I have an Ultra-sonic cleaner that works well for Fuel system components , used a water based fluid with some degreaser and Bi-Carb of soda, some soak time first with a few runs through the Ultra Sonic cleaner at max temp and it brings up components well.  The carb in the picture was done a few years ago so its not as bright as it once was though. 

 

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