223 heat riser valve

[Daves55Courier]

I left out my heat riser valve due to its extremely poor condition when assembling my 223. I installed a long bolt thru the bearings so it wouldnt leak exhaust.
Would it have been better to block off the opening between the intake and exhaust entirely instead ?
After the engine warms up and runs on the highway with that wide open such as it is now, is it wasting a lot of gas due to the heat rising straight up thru that opening?

 

[fmartin_gila]

I will offer my thoughts on this subject. The only real negative I can see is that it may need slightly longer choke application while warming up because the flapper is not directing hot gases to the floor of the intake manifold. After it is warmed up, the entire exhaust manifold is heated and therefore transfers heat to the intake manifold whether the flapper is open, closed, or missing. The main advantage of having the valve in and working is drivability while warming up. Just my thought on the subject, YMMV

Fred

 

[greaseball]

My friend took his out also and it runs fine.

The worst thing that can happen is what happened to me: The thing rusts shut and effectively blocks off the exhaust pipe, causing your engine to overheat and your head to crack. Oil was literally boiling out of my side cover. It's like the opposite of driving with your choke on.

Either make sure it's working properly or get rid of it. If not mistaken, it's only shut when the engine is cold to trap most of the exhaust near the base of the carb, then it opens letting the exhaust out. If it never opens, then you have problems like I did. (see my old posts).

Shane

 

[texas_rat_trap]

So...y'all are saying if the heat riser is rusted to the point that it doesn't move to eliminate it? Mine was so just left it out. But when you say rusted shut...do you mean where no heat is going to the intake...would this be good or bad.

 

[rmt]

My friend took his out also and it runs fine.

The worst thing that can happen is what happened to me: The thing rusts shut and effectively blocks off the exhaust pipe, causing your engine to overheat and your head to crack. Oil was literally boiling out of my side cover. It's like the opposite of driving with your choke on.

Either make sure it's working properly or get rid of it. If not mistaken, it's only shut when the engine is cold to trap most of the exhaust near the base of the carb, then it opens letting the exhaust out. If it never opens, then you have problems like I did. (see my old posts).

Shane

Heat risers don't block off the exhaust, they give the exhaust gases a detour up to the bottom of manifold below the carburetor before going out the tailpipe the usual way. This area heats up real quick, though the rest of the engine is still cold, for better drivability before the engine is warmed up thoroughly. As the bimetal spring heats up, the flap moves to cut off the detour and the exhaust gases go directly out. They have a weight that opens them as the spring tension is released. The default position is open if the spring fails.

My opinion is you want them working for everyday driving. The manifold will heat up eventually without it, but it's there for a reason and doesn't hurt anything, only makes things better. If I had one so bad it couldn't be rescued (most can be) I would do what's necessary to get a replacement back in there.

Shane, I would be surprised if your cracked head and boiling oil had much to do with your heat riser being stuck, even if if it was stuck "closed". (It's never really closed, just re-directed.) The manifold is normally pretty hot when warmed up, the gases are all contained in the same cast iron housing after warm-up whether the flap is open or closed. Temperatures will be normalized though that whole area, one way or the other.

I don't believe an inch or two away that close to the exhaust ports is going to make so much a difference as to overwhelm the cooling system. If the flap is removed it's about the same as if it were in the pre-warmed up condition, with the exhaust gas in direct contact with the bottom of the intake. Does it overheat then?

Roger

 

[greaseball]

Hi Roger,

On my exhaust manifold (223 six), the spring was missing and the counterweight was/is seized. I removed the manifold assembly from the engine and separated the exhaust manifold from the intake manifold. I have an excellent view of the valve positions when open and closed. When closed, the valve forms a pretty tight seal against the wall of the manifold, trapping exhaust gas in the heat riser. If siezed shut, very little exhaust could exit any of the 5 ports (4 normal and two siamesed center ports). I thought that my set up should be louder as I had just put on a Smithy's glasspack, but the thing was dead quiet since little exhaust was actually getting out. I'm surprised it ran at all. Even thought the counterweight and shaft were seized, the valve itself would move freely on the shaft. It probably operated kind of like the flapper on top of tractor exhaust pipes.

Perhaps when operating properly it is never completely shut, but this one was. Along the length of the location where the valve "seats" against the cast iron (just above the flange), the heat build-up caused the cast iron to crack big time. This area is facing the block and is not visible when mounted on an engine. I could hear the exhaust leak, but couldn't see it and I thought it was coming from the flange/tail pipe joint.

Anyway, I got another exhaust manifold with no cracks (but complete with another seized valve). If I can't fix the valve, out it goes and some tapered pipe-threaded brass plugs are going in the holes. When I can afford it, I'm switching to headers. I have an Edmunds dual carb intake that uses water instead of exhaust for a heat riser.

Shane

 

[Drumhead_Dan]

Just as an fyi, my Ford manual says the correct lubrication is part number C0AA-19A501-A FoMoCo sovent and penetrating fluid. The alternate lubrication is listed as a mixture of kerosene and graphite. I'm still working to free mine up a bit more, the spring broke at some point in the past, and I had to really work to get it to open and close.

 

[Drumhead_Dan]

I had mine out today. The flapper itself is supposed to be fixed to the shaft, but its just a little tack weld, I suppose so you can knock the pin out. It looks like the engine I bought had sat in the cold position so long it froze in place, and the entire heat riser was packed nearly full of carbon. At some point, it broke the tack, and it flopped around in there a bit, but not enough I think.

The default position is closed, and unless the spring breaks when its still functional, the valve will be closed. The flapper forces exhaust gas up around the lower intake manifold and then out behind the flapper.

I freed mine and re-tacked it, but I don't see why someone couldn't just take it out if they wanted. The Ford manual says these engines require about twenty minutes to warm up to operating tempurature, so its likely that they do more than just suppliment a choke. There are other things like carb ice and fuel condensation to consider, too.

This is part of the pile I got out of there....

The front and rear risers full of junk.

I forgot to take a pic of the flapper...