The Stovebolt Site Forums The Shop Area Engine Shop 1954 235ci, Stuck Heat Riser and Manifold Question

Making slow progress on trying to get the engine in my project ready to start. The engine seems to have been new/rebuilt(?) by a previous owner, but the parts attached to the engine seem to be used and a bit random.

Yesterday I checked to see if the heat riser valve was free to move...and it was not.

I read over several threads and learned a lot...but I still have questions.

I used a propane torch to head the areas on both sides of the exhaust manifold where the shaft for the heat riser passes through. I sprayed the visible areas of the shaft with PB Blaster. I tapped on the ends of the shaft with a hammer. I tried to wiggle the shaft with channel locks...but didn't seem to make progress. I do realize that spending an hour on this process may not be nearly enough...but...I figured that I would ask in case there were any hints that folks had figured out that may expedite the process. Is it worth the extra effort to remove the exhaust manifold to make freeing up the heat riser easier?

While I was messing with the hear riser, I noticed that (with no carburetor in place) when I look down into the intake manifold, I see a lot of brown glop. When I poked at it, it seems to be a sort of oily residue. I tried wiping it out with a rag, but quickly realized that it would be present throughout the intake manifold and that I would not be able to reach more than a very small percentage of it.
Is this type of glop what one would expect to find in a well used intake manifold? Should I ignore it and figure that it won't cause any harm?
If I need to get the glop out of the intake manifold, how should I proceed to do that? Take it to a machine shop and have them clean it out somehow?

Would I be opening up a can of worms if I took off both the intake and exhaust manifolds?

I would unbolt the intake and exhaust manifolds. It looks like a combination of fuel residue and rust. You could have a machine shop dunk the whole thing in their hot tank, which should remove the glop and possibly free up the heat riser as well. Another possibility for removing the glop would be sandblasting. That would give you a nice surface to paint.
But the heat riser can be freed up by continuing with your heat, tap, PB Blaster method. It'll eventually free up.

That manifold needs some serious cleaning- - - - -either a dip in a commercial hot vat, or some time in a machine shop's power washer, etc. All that crud will eventually end up in that new engine, with some really bad consequences. I do my own "hot tank" cleaning with a strong solution of water and lye in a 55 gallon oil drum, with a wood fire built around it. Greasy residue gets a trip through a similar hot bath, with Trisodium Phosphate as the cleaning agent.

Propane isn't hot enough to free up a stuck heat riser- - - -use acetylene. Heat- - - - -tap with a hammer- - - -"rinse and repeat"!
Jerry

Thanks!

I would assume that new gaskets would be required when reinstalling the manifolds?

Is there anything else I should check while these manifolds are off the engine?

The trick to getting the manifolds to reseal after taking them apart is not to tighten the joint between the exhaust and intake manifolds initially. Bolt them together with the gasket hand tight, bolt the manifolds to the head again with the gasket hand tight, then slowly tighten the bolts sequentially going from the joint that bolts the two manifolds together, then back to the bolts that bolt the manifolds to the head. You want to go slowly at first as you want the manifolds to be able to move in order to get them to align, enabling the gaskets to seal.

Sneaky trick #2- - - -DO NOT bolt the ends of the exhaust manifold to the cylinder head- - - - -there are dowel pins instead of bolts there for a reason. The exhaust manifold has to be able to expand and contract from the heating and cooling cycles of normal operation. If the ends are bolted down tight the exhaust manifold will crack.
Jerry

Thanks for the tip, Phil!

Jerry, I have taken a photo of the head to ensure that I understand what you are saying. In the photo, I have circled two places that I believe you are saying there should be studs instead of the bolts that were there when I removed the manifold a couple of hours ago. I assume that one can purchase the appropriate size studs? Please let me know if I am understanding correctly.

Thanks!

Yes, and it's an easy fix to go back to studs. Simply screw bolts with the right thread length into the threaded holes on both ends, and cut the heads off. Instant guide studs. The thread is 3/8-16, and if you choose the right length bolts, cutting the heads off will leave an unthreaded portion sticking out above the surface of the head. The only purpose of the studs is to align the exhaust manifold on both ends so the remaining bolts and clamps keep it in line with the gasket. The end holes are oversized on purpose to allow for linear expansion.
Jerry

Great! Thanks Jerry!

I've also used short Allen head bolts with the heads ground down to a slightly smaller diameter as alignment studs. Just leave enough room for the manifold to stretch and shrink a little. Easy to install that way!
Jerry

That makes sense.

The end alignment studs came rounded on the ends to aid in getting the heavy manifold assembly started.

Wow, you guys are amazing. I thought the dowels were something some idiot did so I put threaded studs back in after the rebuild. Haven't started it yet during my resto. So out to the garage I go to remove and put the studs back in. Guess I was the idiot. So glad I read this thread.

I took the manifolds to a local shop.

They hot tanked the intake manifold and it is a LOT cleaner!

They got the heat riser to move freely...but that was a couple of weeks ago and it is much stiffer now. It still moves, but not as freely as it did when I brought it home. It is pretty dry here in New Mexico, so I doubt there is any new rust to speak of. Is there a lubricant I should use on it? I was thinking about a product I knew of a number of years ago...it was a spray that carried graphite. Would that be appropriate to apply to the heat riser shaft?

Suggestions?

Thanks!

Lock the heat riser in the closed position. And see what happens.

Texas, I am not sure that I understand your suggestion.

The manifold is on the bench.

When I first picked up the manifold from the shop, the shaft seemed to rotate quite easily. Now, the shaft still rotates but there is some resistance in some spots.

Once I got the manifold home, I noticed that there was not much spring pressure at all trying to keep the butterfly in the cold position. At that point I wound the spring one turn tighter figuring that the shop might have undone it and not retightened it.

If I heat the spring with a torch, it relaxes the pressure on the butterfly allowing it to move more freely toward the position that would force the exhaust to go down into the exhaust pipe rather than up under the carburetor, but it doesn't relax it enough for the butterfly to close off the upward flow much at all.

If I manually move the butterfly to either extreme, it gets a bit stuck.

So, at this point I am guessing that what it needs is some sort of lube.

I have attached a couple of photos which I labeled with what position I believe the butterfly should be in when cold and hot. (I am confused as to what we are calling open and closed.)

The shop did a "half-donkey" job of cleaning the pivot shaft. Heat the shaft where it goes through both sides of the manifold and tap it forward and aft to clear out the rest of the carbon fouling that's making it stick. No lube should be needed once all the contamination is cleared out- - - -exhaust gas heat will simply make any kind of lube coke up as soon as the engine is run again.
Jerry

I agree with Hotrod Lincoln. However, I had similar issues here in College Station Texas and since temp here don’t (most of the time) drop to requirements for carb heat I just compressed the spring to retain the heat riser valve open all the time.

You should probably buy a new spring for it.

Try a new spring. Here's one that works well on a stovebolt manifold, at a fraction of the cost of an OEM part:

www.ebay.com/itm/182196172425?

Jerry

I appreciate the suggestions.

Using alcohol, manually moving the butterfly and lightly tapping the shaft one way and the other, it is moving very freely now...except occasionally. The spring seems good and strong.

I believe that I caused the problem. When I got the manifolds back from the shop, the heat riser valve moved easily and the manifolds were both so clean that I dove right in and painted them - without any thought to getting paint on the heat riser shaft. So I believe what is causing my issue is the fact that the stupid painter (me) didn't mask the places where the shaft it enters the manifold.

It seems to work most of the time now, and I am hoping that when the engine gets to actually running, that it will be dependable. (Maybe I ought to face the music and go get it hot tanked again, before I bolt it all back together...)