Technical 46' Pontiac Heat riser open or closed?

Did a bit of research and I'm still not sure. Picture shows it's current stuck position. It's a 1946 Pontiac 8 and the riser is stuck. Started PB blasting it today and I will start with light hammer taps on the shaft after it soaks in a bit. If it's stuck "open" I'll just leave it... Runs great when I first fire it up. When It warms up it wants to die when I come to a stop. If it dies it starts right back up. I can keep it running by reving it up a stop signs. Everything is original 6 volt. Thanks for sharing any wisdom..

 

Patience, sahib. Some of us have day jobs.

That's stuck halfway open if the flap hasn't been bent.
Full open is at a 1 o'clock position (with the pointer of the imaginary hour hand in the middle of the heaviest part of the weight). Full closed about 5 o'clock.

The bi-metallic spring on the other side should relax when cold, pull the weight up when hot.

Soak it down with PB blaster, but they are notoriously difficult to unfreeze; it should move quite freely in normal condition.

Phil

 

Thank you Phil... The clock reference is very helpful. Would stuck half open affect how she runs greatly? I intend to free it up..Hopefully

 

If it's stuck closed it could cause percolation in the carburetor when hot.. That would, in essence flood the engine when hot. The main job the heat riser does is to heat the hot spot in the intake manifold to more effectively atomize the fuel when cold. You can eliminate the thing but it would take longer for the intake to warm up and the engine would want to die at idle. Another thing it helps to eliminate is icing in the carburetor at the throttle plate in cold humid weather. The spring holds it closed when cold and it gradually lets it open as it heats up. Getting one unstuck can be a real headache.

 

What Glenn said.

I am going to be by mine Saturday, I'll take position reference pictures again- I had a while ago but couldn't find them.

 

Thank you Glen & Phil, your knowledge and willingness to share is much appreciated. Phil- A picture would be great. Thank you..

 

You would probably benefit with carburetor rebuild and a complete tune-up. It would be a good idea to check the ignition circuit from key to distributor and check all grounds.
It you take the carburetor off for rebuild, you may can reach the heat riser. Otherwise, you may need to remove the intake. This way, you can work on it and try to free it from the inside.

 

The heat riser flap is inaccessible from above. Access to the shaft is via removing the exhaust downpipe and getting to it that way (without splitting the manifold, which will not be a fun task- 4 broken studs guaranteed. Ask me how I know).

Phil

 

Duh!!! You are correct! Every now and then I have brain fart.
I think several sessions with a small hammer just pecking on it may free it up. Not going to town with the hammer...just pecking on it to vibrate it may free it up.

 

Agreed, mine has about 1/16" sideways lash. That should be enough to try get some movement. Wouldn't bother with heat very much, there's too much metal there to soak it up.
PB over a few weeks should get inside and creep enough to get some motion.

May pay to get up inside, there's always a lot of acidic sooty deposits to cause the shaft to jam after being sat a long while, especially in a cold/damp climate.

 

Oh, and on the topic of heat, I procured a factory option heat shield for mine that bolts on between the carb and manifold- that helps when the car is hot and at idle also.


(From another thread, showing the heat shield, vacuum line and idle screws on the Carter WCD labeled).

Also you can see the position of the weight in the "hot" position here where I was doing my valves:


Phil

 

F-one your spot on about the grounds. I had a no -start and it was a loose ground. I ordered a NOS tune up kit that should help. I'll pull and clean all grounds too. Rebuilt carb is on the way... Phil, I was thinking the same thing. Drop the exhaust and lock some long reach vise-grips on it. Thanks Fellas...

 

There's nothing to grab up inside, the flap obscures the shaft.

PB blaster and patience.

 

Wow Phil, that's awesome. I can see from the photo mine is kinda far off. Well looks I have some knowledge now and my work is cut out for me. As soon as above 15 degrees here in the Midwest I'll get back after it. Thank you for your input, I sincerely appreciate it.

 

GM sells a penetrating oil with graphite specifically for heat risers.
10-4020 / 88862628

Tests of penetrating oils in my opinion can't help but be largely inconclusive, but so far my opinion is the GM may be a**** the very best.
Hard to find less than 12 US bux

 

Thank you Dan!

 

Haven't read all the above, but who's to help with a 46-foot-long Pontiac. I wanna see the picture!

 

Got her broke loose tonight ..She PB blast soaked for a few days and I tapped the shaft from both sides with a punch. Second round of tapping I saw it move a tad. Grabbed it by hand and it budged. Sprayed it again, waited a few and it broke loose. Gonna blast and exercise her one more time. Thanks again for all the insight. No subs***ute for knowledge gained through experience.

 

Stan- Had to extend my garage to get her in...It was a rare option.

 

Most excellent! As said, graphite lubricant (also good for door locks).

You can test it by gently waving a blowtorch flame at the coil, check it moves the full range.

Phil

 

Cool, I'll hit it lightly with my MAP gas torch. Thanks again!