So- my 215's heat riser is not automatic any more. Last year I was able to free it up to manually move the shaft through the complete range of travel.
Questions-
Since it's now manual only- what position do you think it should be in for the summer?
Why?
Which way is the weighted end oriented when the flap is open-closed?
I am guessing that the flap is meant to be fully open with cold engine, and fully closed with hot engine- is this correct?
I've not found anything in the manual, and searching this site gave me lots of hits- but I didn't find a picture of the manifold with the weighted end of the shaft showing what position open or closed was...

 

Closed when engine is cold, to divert a portion of engine exhaust through intake to warm fuel/carb and prevent carburetor icing. Open for normal operation. With engine idling should be able to hear exhaust note change when you close/open it. A lot of guys will remove the flapper or wire it open. Takes a little longer to warm up.

 

I've posted this parts catalog pic several times in the past, but my computer has a glitch, so until the darn thing is fixed, I'm SOL

The flap usually gets stuck in the partially or fully opened positions.

If you wish, I will look and see if any of these obsolete parts are available NOS

 

Thank you. I couldn't discern any change in the exhaust note while moving it at idle.
Anybody know what the weighted end should look like when flap is open?
I want to move it to that position for the summer.

 

Thanks Bill!
I don't have the parts manual-just the shop manual.

 

1948/56 Ford Truck Parts Catalog available on a C/D from hipoparts.com

Includes chassis parts only for 1948/52, chassis and body parts for 1953/56.

1944/52 Ford Passenger Car & Truck BODY Parts Catalog is not available on a C/D

You either have to find an original bound paper catalog, or buy faxonautolit.com reprint, but it's 1/2 the size of the original and costs 75 bucks.

 

I think most folks on here, when they say open / closed, they are saying that in relation to the exhaust manifold pipe chamber, and flow of exhaust gases through it. I think of open / closed as the path up the manifold to the bottom of the intake. And in that regard, when closed, you can hear the flapper close on the edge of manifold lip. Open, there really shouldn't be a sound, as the flapper is vertical and not hitting anything, letting the hot gases warm the intake mixture.

The flapper is welded on the shaft, and if you don't hear the flapper hitting anything on rotation or change in exhaust sound, you may have broken the weld in your freeing efforts. Not uncommon at all to ruin a few parts when trying to free it.

Heat riser parts are like finding hens teeth.

JB

 

B4A-9467-A .. Exhaust Thermostat Control Valve Coil Spring / Obsolete

1948/51 226 I-6; 1950/53 254 I-6; 1952/53 215 I-6; 1954/64 223 I-6.

NOS PARTS LTD in Waxahachie TX has 1 = 972-937-2201.

MILLER OBSOLETE PARTS in Binghamton NY has 1 = 607-722-5371.

CROSSETT FORD-LINCOLN in Crossett AR has 2 = 870-364-2162.

 

Here's a couple of pictures showing what I believe to be "flap shut/warm engine operation"...


Thanks JB-
That makes sense to me, I rotated the shaft back and forth- and noted at one position the sound and feeling of the flap making contact inside the manifold.
It also seems to make sense that Ford would have designed it so that if the spring breaks- the counter weight would let the flap close- for most common operation-a warm engine.

 

One of the reasons I was interested in doing this is because today its 93 degrees, after a 25 minute trip, and then sitting for 15 minutes it was hard to start, had to crank a bit longer and floor the accelerator pedal to get her started. Then still seemed to run a bit poorer than usual on the way back...I am aware of the other things that may cause the hard hot start, but I did have the flap turned the other way- open I believe- which would not help a hot start scenario, or hot weather driving.

 

Here is the picture ND was referring to for the 215/223

 

I think JB has it right- I looked at how it works and it appears the flap is CLOSED when engine is warm- preventing warmed air from rising from the exhaust manifold up to the intake manifold.
I closed it and drove it 10 miles yesterday afternoon in the 93 degree temps, shut it off and let it sit 15 minutes and it restarted much better than earlier with the flap OPEN.

 

The "open" flap is the normal configuration (engine warmed up) if we're going to define our terms here, right?

Anyway the purpose of the heat riser as I understand it, is mainly to prevent carburetor icing. Under certain atmospheric conditions - high humidity and well above freezing temp, the venturi effect can cause the carburetor throat and butterflies to ice up. I've seen this happen one time and it happens really fast.

So a hot start problem seems to me, is probably something else - vapor lock, fuel percolation etc. Modern gasoline is formulated a lot differently than it used to be, since the advent of fuel injection. When most cars had carburetors, the resistance to vapor lock was an important consideration in the fuel blends. Something called the Reid Vapor Pressure index or somesuch. They don't care about that now. On a hot day with a hot engine the fuel will be literally boiling in the fuel pump as well as the carburetor bowl. I've been meaning to measure the AFR at idle under those conditions. The fuel boiling should throw the idle AFR way off compared to just a few degrees cooler.

It may be just a summertime adjustment of the idle fuel mixture will help your issue, and/or maybe lower the float height a tad from stock spec. Try running MMO in the fuel. Old timers used to add a pint of Diesel in the gas per tank. Worth a try anyway.

 

Leave it "open" and you can literally hear the gas boiling in the carb after killing the engine. No way you have a successful start after that.

JB

 

Ted, it works just the opposite from a V8 on the I-6 215/223. When open it directs the exhaust under the intake, closed it directs it straight out the exhaust pipe.