Manifold Heat Control Valve?? (1 Viewer)

[thebigredrocker]

My flapper was loose on the shaft so I pulled it apart.

Does the bend in mine look correct?

I temporarily re-installed the flapper in the same orientation I found it.

This would be cold

Here's hot

 

[thebigredrocker]

Here's with the flapper opposite how I found it

Cold

Hot

 

[73FJ40]

Search for thread "part seldom seen" page 9, post #173. The concave surface should face the engine cold. If you need a picture of a NOS flapper, let me know.

(Working from a kindle fire right now, so I can't post links)

 

[algeeba]

I was researching this issue as well about a month ago. The flap on my 1F manifold was set up like yours, Big Red, and it struck me that that is not the way it should be. Either it was set up intcorrectly or the flap had been bent. In the hot position it would appear that hot exhaust would still be hitting the intake manifold.

Then, finally, I had found 73FJ40's pictures and that setup makes much more sense and is how I will set mine up.

 

[73FJ40]

I also found an alternative for the NLA Toyota heat riser coil spring:

Part Seldom Seen

 

[algeeba]

Which I will be getting as well. Thanks 73FJ40, have loved your posts.

Anywhere to get the exhaust flange? Sorry for the hijack.

 

[thebigredrocker]

@73FJ40
If I am understanding your picture correctly, then someone did have my flapper installed backwards. The flapper had one rather large blob of weld present, which had broken free from the shaft. Whoever welded the flapper dug deep into the shaft, the welds failed though.

Also, what appeared to once be a threaded hole in the shaft had what looked to be a broken off chunk M4 machine screw. It was a bugger to drill out.

My guess is, my flapper has been bent. It's at about 37mm in the picture. A pic of your NOS flapper would be helpful. Don't go through too much trouble though. Now that I know concave on engine side, convex on fender side, I should be able to bend it back close to spec. I appreciate your help.

Also, if anyone has a "counterweight stop bracket", I could use one. Mine was missing.

Bracket picture is 73FJ40's

 

[73FJ40]

@algeeba

I haven't searched for a replacement flange, yet, but if you were to search on "AP exhaust flange dimensions" you may see a bunch of universal flanges, at Summit Racing.

I did take the time to trace and measure the new flange I have. The dimensions are nominal, since it's likely the original was metric. Here it is:

 

[ryanwk628]

I just welded mine in the hot position. Put a tack on the shaft to keep it from moving and another on the manifold. Posts 25, 28-30 in my thread. My logic was that it has been running for a long time just flapping in there so it was not adding any value... probably getting pushed towards the warm position because flow wants to take the path of least resistance.

 

[thebigredrocker]

I just welded mine in the hot position. Put a tack on the shaft to keep it from moving and another on the manifold. Posts 25, 28-30 in my thread. My logic was that it has been running for a long time just flapping in there so it was not adding any value... probably getting pushed towards the warm position because flow wants to take the path of least resistance.

If you still have your counterweight stop bracket and are willing to part with it, I'd certainly be interested

 

[thebigredrocker]

No plans to do this, but I've wondered if anyone has ever rigged up a cable to manually control the flapper. Perhaps in conjunction with a temp prob to measure and display the intake manifold temp.

 

[ryanwk628]

If you still have your counterweight stop bracket and are willing to part with it, I'd certainly be interested

Sorry, I didnt have one on either of my exhaust manifolds (I have a spare set I snagged of CL with some other parts.) I have the same cast piece shown on the right side of the photos in post 1. It seemed to act as a stop on its own were there a spring expanding as it got warm and rotating the rod towards the hot position based on where it contacted the manifold relitave to the location of my flapper. There is also only so far the valve can travel inside the manifold before the bottom part bottoms out on either side of the outlet.

Hard to see but it can only travel so far... unless your worried about spinning it on the shaft. I cleaned mine up and put a tack in the middle.

 

[73FJ40]

@thebigredrocker

I've got some 'free' time since we're in the middle of a pretty good-size snow storm:

Yes, you're flapper is bent a lot more than stock. Here are some pictures of my NOS parts:

Note that in the position above, the left end of the flapper measures 1/4" from the cardboard surface to the top of the flapper.

The flapper plate is flat from the left side all the way to the right side, EXCEPT FOR the last 1/2" or so, (where it looks like a tongue) which is gradually bent downward just enough to keep the 1/4" measurement on the left side.

I've also included in the pictures the shaft with counterweight and the hairpin clip that keeps the shaft centered in the exhaust manifold. There should be two of these clips, one for each groove in the shaft.

As noted in my 'parts seldon seen' post, the flapper was attached to the shaft with some pretty significant TIG welds from the factory, so it seems clear to me a little screw won't cut it.

 

[algeeba]

@73FJ40, excellent pictures. What recommended thickness for the exhaust flange since most likely I'll have to make one out of flat stock, in case I can't get a hold of a used original one or cannot find one close enough to your dimensions. Will also make my own flapper as my used one is pretty shot.

@thebigredrocker, it may be easier to make that bracket and make those "C" and "H" letters. I have one for my manifold and I can get you some dimensions unless 73FJ40 already has some.

 

[Trollhole]

@73FJ40


Also, if anyone has a "counterweight stop bracket", I could use one. Mine was missing.

Bracket picture is 73FJ40's
View attachment 1398750

I thought I knew just about everything when it came to 40's and you sir just proved me wrong. I have never seen a stop bracket. Too cool.

 

[73FJ40]

@Trollhole

You're not wrong, just 'slightly underinformed."

You're also in good company, 65swb45 had similar sentiments:

Dude, that is friggin cool! And definitely seldom seem. Reminds me I need to dig out this really cool plastic adjuster knob for s&g.

BTW, it looks like you need a new booster fitting for your intake. I would change that out before finish installation of the manifolds to make sure no debris from the swapped fittings get sucked into the motor.

 

[65swb45]

Found this floating around in the bed of my truck. Forgot what it was. ...but I remember now!

 

[73FJ40]

@73FJ40, excellent pictures. What recommended thickness for the exhaust flange since most likely I'll have to make one out of flat stock, in case I can't get a hold of a used original one or cannot find one close enough to your dimensions. Will also make my own flapper as my used one is pretty shot.

@algeeba
I think it's common practice to use 3/8" material if you intend to fabricate from flat stock. The OEM has rolled edges to obtain adequate stiffness from a thinner material.

 

[thebigredrocker]

Picked up some 1/4" hairpin clips from my local hardware store for the heat control valve shaft. They were a bit too long so I sliced off the tips with my dremel and curled the other end so as to not bind.

 

[65swb45]

Haven't forgotten you Mark. Slowly pulling parts for your order. Last pair of factory long jump seat belts. All 4 ID tags intact. Chrome will have to be refinished.

Nov 1971