The heat riser on my '39 seems to work, but the shaft is worn and the manifold hole also looks worn. The problem is that there is a pretty good exhaust leak here. I have a diss- assembly question. I have the manifold off. The weight looks like it is pinned to the shaft. I removed the spring. My question is how is the plate connected to the shaft? Can I just drive the shaft out or is there some kind of connection between the plate and shaft. I do not see anything, but my eye sight is not that good either. I plan on turning a new shaft. Is there bushings in the manifold or does the shaft just wear against the manifold? Thanks for the help. Mike
The plate is secured by rivets (most likely) or welded to the shaft but once these are undone the shaft will come out easily considering yours is worn and loose. Tony
The heat riser on my '39 seems to work, but the shaft is worn and the manifold hole also looks worn. The problem is that there is a pretty good exhaust leak here. I have a diss- assembly question. I have the manifold off. The weight looks like it is pinned to the shaft. I removed the spring. My question is how is the plate connected to the shaft? Can I just drive the shaft out or is there some kind of connection between the plate and shaft. I do not see anything, but my eye sight is not that good either. I plan on turning a new shaft. Is there bushings in the manifold or does the shaft just wear against the manifold? Thanks for the help. Mike
If memory serves me right you'll have to drive the shaft out , It is probably rusted in there so it will need some wd-40 to loosen the pin. there no bushings , metal to metal only.
p.k.
1956 BEL AIR 2 DOOR HARDTOP
I've spent most of my money on Booze,Women and mechanical things. The rest I just Wasted........
Remember , I'm not Always Right. But I'm Never Wrong !
Well...... I've been cleaning and chipping away at all the carbon accumulation on the riser plate. I do not see any rivets or screws between the plate and shaft. I do see what looks like two spot welds. One on each side of the plate. I'm going to try and grind away at the welds to release it.
I see that Chev's of the 40's has a replacement shaft and thermo spring, but no replacement plate. Does any one know where a riser plate can be purchased? Thanks Mike
Here are some pictures of the exhaust manifold used from 1940 to 1948. These years there were bushings, the heat valve was welded to the shaft, and the weight was pinned in place on the shaft. There is no simple solution in solving your problem as the aging process of the metal makes it hard to remove the weight, so try not to mess with it. You will need to remove all welds on the plate and maybe things will slide easily out. The end of the shaft might need to be compressed where the spring slot is or even cleaned up a little so it will slip out of the manifold. Don't try to force anything as the pot metal can break or crack. New bushings could be your best solution if you cannot locate a manifold in better condition.
A leaking manifold could be caused by someone not mating the manifolds together correctly or installing it to the head correctly. Has yours been off recently? Do you know the history of your engine?
Please read your manual for more advice, especially on the tightness of the spring for the heat valve to work.
Mike, thanks for replying and the pictures. After cleaning I can see the weight pin and the welds on the plate to the shaft. My car is 1939 and I can not see any signs of a bushing on either side of the shaft. Looks like the shaft just bears on the cast iron. I have a couple of other manifolds that are damaged and they also do not show any sign of a bushing. But, I could enlarge the hole and install a couple of bronze bushings that fit on the shaft. I also think that I'll have to turn a new shaft. We'll see, I'm just inching along. Pretty sure I can drill out the weight pin. Right now my time is being used trying to free the riser plate without damaging the plate. Thanks again for the help, Mike.
Mike Z Carefully grinding the welds to release the plate (after noting the position of all parts) should allow the shaft and weight to slide out. When you make (or get made) the bushes dont use brass as it will melt with the heat in that area (someone else posted this issue), use stainless steel and if the shaft is beyond reuse stainless would be advisable. Tony
Thanks for the help. I have the manifold in an acid bath right now. I hope to clean it up for some heat paint. Once it is out, I cut the plate out as you said and use some stainless bushings. Thanks again. Mike I'll get back in a few days.
Another road block! I finished making a new shaft and bushings got it all assembled and while tightening the exhaust flange to the manifold, I hear a snap. Sure enough the cast iron flange cracked. There is only one crack and no part of the flange broke off. What is the best way to repair this? Can I braze the crack or can it be welded? What are my options, besides finding another manifold. Rats, Mike
Yes, events like this can be frustrating. I will let others offer guidance on whether to repair the manifold and if so the best method.
I suggest that the failure was probably caused by a warped (not flat) manifold. The distortion was so large that tightening the bolt was more than the cast iron would flex. Whether you repair this manifold or get another used one you need to check for flatness and alignment of the exhaust flanges before you install it.
There are multiple posts about how distorted these exhaust manifolds get over the years. The multiple heat cycles take their toll. Once you release the bolts the flanges go any direction they want. In some cases the distortion is so great that it is very difficult to even get all the bolts installed.
Most machine shops that do head work will also have a sanding/grinding machine that will make the mounting flanges flat and aligned.
I'm sorry that I was not clear, the flange I'm talking about is the exhaust pipe flange. The port flanges are OK, I checked them prior to working on the manifold. Mike
I was fortunate to find a welder who welded my exhaust manifold when it fell from about 7' and broke the end off. I had it drying after I painted it. The coat hanger came unbent. You will need to call around to find a welder with this kind of experience. I have had no trouble with the weld holding up over the last 15 years and most would not even notice it has been welded. I painted it with POR 15 which sells a heat tolerant paint. You have to be very careful using the paint as it requires reading the directions to get a good job. I also set the paint by putting it in my gas grill for about 1/2 hour or until it stopped smoking.
I do not remember what material was used for the weld.
Well...... I had some success, the crack was welded up and the exhaust pipe bolted up and all seems fine. No exhaust leaks BUT, the extra exhaust manifold heat riser counter weight broke as I was trying to install a new shaft. More work, but the car runs good.Thanks for the help.
