Heat riser temporary fix

[Uncle-Pekka]

The manifold heat riser in my D24 is shot. At least the spring is broken, may be some other parts missing as well - I do not know, because the shop manual I ordered has not arrived here yet.

However, I suspect the over heating of the intake manifold does tricks, thus I'd like to shut the heat valve by fixing the mechanism with e.g. wire.

The problem is, having not pulled the manifold in parts, I do not know which position is open and which closed. Help, please!

See attached photos of my engine: These are the positions the valve goes.

[DonaldSmith]

The second picture shows the valve in the closed position, which is normal for a warm engine. Otherwise the hot exhasust gases will overheat the base of the carburetor.

[greg g]

Just ot verify the spring counter acts the counter weight. Gravity will put the shutter in the closed (feeding exhaust to the intake) position. I believe the full clockwise position in the second pic is open (allowing the exhaust to make the most direct exit.

[captden29]

i have the same question about my heat riser as without looking in the manifold how do you know if it is open or closed. since mine will turn but with great difficulty i just put it in the half way position until i can get the manifold off and either get it working right or just eliminate it. i think eliminating it is the best idea. it worked fine last year but after sitting several months over the winter it froze up. it appears to have been replaced at one time as it has a nice shiny clean shaft, but rust gets in on the side you cannot get to with penetrating oil. i always despised these damn things anyway and when i had the chance to eliminate it on my 53 imperial i did not hesitate to do so and there were no problems at all after i cut it out of the car. dennis

[greg g]

Here we go. This shows the riser flap in the closed position. Closed because it shuts off the intake heat chamber from the flow of exhaust. I beleive this info is already in the tech archives but if not, maybe GTK can add it. Mine is welded in that position. Even driving with weather int he 30's and 40's I have never noticed a big problem with cold running.

[Uncle-Pekka]

Thanks Folks!

Gregg's photo and Shel's picture from the shop manual makes it crystal clear.

After I got the gas tank cleaned and the heat riser air valve closed the engine performs much better - as I expected.

I wish my manual would finally arrive... Lot of issues would be nice to check up from THE SOURCE.