Exhaust heat riser

Roger Harmon

All,
In my continuing efforts to improve hot (operating temp) starting with available fuel, I want to secure the exhaust heat riser valve in the open position. I believe I can safety-wire it in the desired position: Is that with the little lever on the shaft all the way up or all the way down?
R/ Roger.

[Deleted User]

Start your engine, then get on the right side hood up, then gas engine and you will see counter weight move up. Tie it all the way up using a wire coat hanger around the exhaust manifold. Tie it tight. Walt.

tigermoth

roger, i made a stainless steel blanking plate for the opening. regards, tom

RonS

This is driving me nuts. I always thought, that on a cold engine, with the spring disconnected, the riser valve is pulled( defaults) to the open position. If, on a cold engine, you connect the spring the spring overrides the weight and pulls the valve closed. As the engine get hot the spring expands, becoming of little value and the weight pulls down the valve in to a "free fall" and open. Please tell me why must the weight be tied open, since gravity will accomplish the same goal. In a free fall ( disconnected & hot ), I for the life of me, can not get the weight to move when I goose the engine.

Geoff

There is a slight confusion here, in that the weight does not actually move up or down, but in a semi-circle. Looking from the right side of the engine, the weight is towards you, held there by spring tension. As the engine warms up the spring tension decreases, and when the engine is revved up the gas causes the flapper valve to move the weight towards the engine (counter-clockwise looking from the rear). So you need to wire the weight inwards towards the engine block.

RonS

Geoff , That is true, however let us assume that the spring is not connected at all. The flapper weight will fall lower to the 9 oclock position( looking at the engine from the passenger seat). That is the open, or fully warmed position, that the valve would be in if the spring was connected. So, disconnect the spring and leave the weight do its thing... Valve in fully warmed position. Ok, you guys say that the valve gets sucked closed on rapid reving of the engine. I tried to do that last year. I could not recreate that. The valve weight was too heavy and even if the weight moved just a bit, the driver would hear banging, as if two pipes were stiking each other, when the engine speed ( and exhaust rush) is varied. Granted there probably is a bit of movement from vibration, but this is necessary in order to keep carbon and stuff from forming that might eventually freeze up the flapper. Also, if the weight was dislodged and the flapper closes up, there would be a intermittant exhaust restiction affecting performance.

[Deleted User]

Geoff, we are wasting our time, as they do not understand the heat riser problems. Again, it moves counterclock to open so must be tied in the up position. How are we going to get these people to just do it and enjoy? If weather is 30 degrees and under, they have to make sure the heat riser works or the carb will put raw gas in the engine and that does not burn. Walt.

[Deleted User]

I just cut all of it out and ran a long head bolt through the pivot holes. do not think I need a heat riser in south texas..ha.Of course I had to do this when replacing the intake exhaust gasket. Straight pipe no restrictions. do not know if this will cause vapor lock later.

[Deleted User]

You just helped the engine so that vapor lock is not really going to be a problem. Exhaust manifold will run a little cooler and less heat towards the fuel pump. Walt.

Lee ODell

By removeing the manifold damper on a 212 engine will there be a performance improvement and a reduction of vapor lock problems?

Lee O'Dell

[Deleted User]

Thanks, that confirmed what was done .My needing to fix this issue where I don't think I could have found the parts to fix it back to stock. Makes sense that it would be cooler due to less backing up of exhaust. I only know enough about cars to be dangerous,but do not let this stop me from doing the best i can. I love this engine design and history and only a few issues seem to need to be changed ,in design when i rebuild this 80,000 miler that has sat for 16 years. You should hear the lifters and values .#@$%^&@# ha. Have never seen a timing chain so stretched and worn before ever on an old engine. Surprised that Hudson did not change this design?