I have a 1969 240 with an Autolite 1101 carb, stock intake and exhaust manifolds.

The heat riser valve is stuck on the exhaust manifold. It is in the position allowing the gases to enter the heat riser, warming the carb. Runs OK, but has some trouble in hot weather. I'd like to fix it.

I have a set of EFI split exhaust manifolds. But I have not installed them because of my concerns that in cold weather I will have trouble with carb icing. I live in an area that has very hot summers, and can have very cold winters.

I have heard of various solutions to this, including heat plates, hot air risers welded to headers, etc.

I am thinking of the following: Fabricating (or buying, if available) a plate to bolt under the stock intake manifold, creating a watertight chamber. Plumbing that chamber with water from the heater lines.

I plan to put a valve somewhere, so as to vary the water flow if needed. My worry is that:

1) What if there is a water leak INTO the intake manifold? I wouldn't see it, until I have lost a lot of water and antifreeze through the engine. The intake heat riser casting is tight enought for exhaust gases, but what about water?

2) Do you think I can get the plate water tight under the intake? I was thinking 1/2" aluminum, but I can use steel if need be.

3) Will I rob too much water from the heater and have cold feet in the Winter!

Thanks -- I tried the search engine, but no other idiot seems to have done quite this yet! Oh -- please don't tell me to get a Clifford manifold. For now, I want the old autolite, and that is wedded to the stock manifold.

 

I'd try to unstick the heat riser first. Mine was good and stuck, and I got it loose. Has been fine since. Spray for a few days with a good penetrant. Keep it soaked around the shaft. When it's soaked for a long time, start tapping on it with a light hammer. Not hard enough to break it, but hard enough to slightly loosen the rust a bit. Keep doing that for a while, while keeping it sprayed, and I bet it will come loose. Then just keep spraying it with a good lubricant spray. Keep working it back and forth until it feels free. You can test for normal operation by starting the engine when cold. When cold, the valve should be in the "heater" position. But if you goose the gas, it should quickly flap towards the normal exhaust position, but go back to heater, when you let off the gas. Once the engine is warmed up, it should be in the exhaust position, and stay there while the engine is running. If you had to go with the EFI manifolds, I'd probably try to rig up some kind of "stove" with a aluminum hose. Kinda like the newer models in the 80's etc.. But I bet you can unstick that one you have. You'll just have to work with it for a while. MK

 

Do you have the older style intake that doesn't have the small hole for the air injection? If you have an older motor I'd suspect not - you should have one of those nice carb spacers that don't have the EGR hanging off the side. The reason I ask is that could be a problem area. You won't know for sure untill you take it off, flip it over and fill it with coolant. As your cautious action is wise I'd definelty would test it first. An extra intake would be nice for this. I also think you'll be best off using a material that will expand and contract as most like the cast iron - go with steel, milling in a groove for an O-ring may work well...or maybe trying a copper gasket - clearance maybe tight for the o-ring idea, but keep in mind there will be some pressure in there. You may need to mill a little off the center ridge (of the bottom of the intake - where the heat riser opening is) to ensure coolant to both sides? I think I remember there begin some sort of ridge that splits to forward and rear sections of the manifold - it has been a while. A junkyard piece might be the best test fixture to try. You're breaking new ground here.

 

Actually, in the process of reading about a hundred posts about exhaust manifolds all over the place, there are others that have done this "heat plate" idea over the heat riser in the intake manifold.

In fact, a couple of posts mention being able to purchase the plate ready made. Stovebolt makes them for che**y manifolds which apparently used a similar setup along the way. But I can't really locate anyone yet. fordsix.com is down, but I bet someone over there may know.

On a mission now -- would like to use those split manifolds.

Thanks MN5K and tetraruby --- yes, I think I will try to unstick it too. I have a cracked manifold from my donor engine that has a functioning valve. I may try to bust the bad manifold apart very delicately, to salvage the valve, and then very carefully drill out the bad valve from the good manifold. Probably a long shot, as they are both pretty old. But worth a try before scrapping both.

I have a donor intake too, but it was under a Carter YFA that had an EGR valve and setup. But I don't recall seeing any extra holes in the intake manifold proper. Need to take a better looksee. And, I seem to recall that the carter and the Autolite had a different bolt spacing. Hmmmmm