Manifold heat control valve?

[ramblinn]

Stock 70B right side HP manifold with the heat control valve:  would like to get it working, but not sure how.  It seems to have all the parts and the flap moves freely.
 

As you can see from the pix, the flap is normally open (shouldn't it be closed?).  The tab on the thermal spring just lays on the post.  When I apply heat the thermal spring expands, but the tab just moves away from the post without effecting the flap.  Seems like the tab should either be attached to the tab or   If I vice grip the spring tab to the post, apply heat, the flap moves to a closed position (not good right?).  The FSM doesn't help me much.  Anyone understand how this mechanism should work?

[Nacho-RT74]

it should be open and when coil spring gets hot ( bimetal piece ) gets open...

as I understand what you say, I think the spring coil could be backwards... turn it around to be able to push the flap when cold

it needs to be tensioned too...

I never have seen one assembly working but using the logic its what I can imagine

[ramblinn]

Thx for response.  I thot they were closed when cold (startup) to recycle heat through the intake manifold.  Then gradually open as the engine warms up.  Not sure how I'd turn the spring around as you suggest as the counterweight seems to be welded on.

[mpdlawdog]

   I have a 68 with stock manifolds on it....I could not figure out why my car was running so hot....come to find out (after two weeks and several cussing sessions) mine was stuck shut...I wired it open and problem solved....It looks like the same set up I had but if you are not driving it in winter you really dont need it....

[ramblinn]

A lot of folks say the closed valve helps even cold starts during summer, heating the mixture and such.   I'd like to get it working like its supposed to.  After looking at it and with the suggestion above, I think somehow the spring got reversed.  Got to figure out how to get the spring out and turned around.

[Nacho-RT74]

I guess remove all the assembly. Shouldn't be so hard

[ramblinn]

Yea, I think I have to separate the flap from the shaft, then I can slide the counterweight/shaft out and reverse the spring.

[maxwellwedge]

You have to grind off the welds on the flap to start the process.

My advice......If it is open all of the time - leave it alone.

Even on my full blown resto's I cut the flap down to almost nothing.....enough left on to keep the shaft from sliding side to side.

I burned up some valves with a stuck shut flap once. Never again. As long as everything looks stock on the outside be happy with the thing wide open.

[ramblinn]

Unfortunately the spring orientation (no tension) allows the flap to move, so it might close at inopportune moment.  I guess I'll either grind off the flap as you noted or just weld the flap open.  Weld would eliminate possible rattling of the shaft.

[John_Kunkel]

If you look at the butterfly valve you'll notice that it isn't centered on the cross-shaft, the larger side of the butterfly allows exhaust gas pressure to push the valve open against the resistance of the coiled spring. Although the spring does loose some tension as it heats up it doesn't make the valve open by itself, exhaust pressure does that and the more pressure (higher rpm) the further it opens.

[ramblinn]

If you look at the butterfly valve you'll notice that it isn't centered on the cross-shaft, the larger side of the butterfly allows exhaust gas pressure to push the valve open against the resistance of the coiled spring. Although the spring does loose some tension as it heats up it doesn't make the valve open by itself, exhaust pressure does that and the more pressure (higher rpm) the further it opens.

I'm trying to understand this.  It isn't centered as you note.  This first 2 pix shows the valve in the rest position with the spring tab against the post, with tension, and the butterfly mostly open.


I can rotate the counterweight by hand CW about a 1/4 turn, against the tension, to close the butterfly (pic).


When I apply heat to the spring, from the rest position, it expands of course and moves off the post (pic).  Now the butterfly is free to move within the range between the tab and the post.  Is this how its' supposed to function?

[charger Downunder]

Either the coil spring is on the wrong way round or some one welded it on the shaft in the open position when cold at time of installation. Get rid of it.

[bobs66440]

Unfortunately the spring orientation (no tension) allows the flap to move, so it might close at inopportune moment.  I guess I'll either grind off the flap as you noted or just weld the flap open.  Weld would eliminate possible rattling of the shaft.

Mine rattles like mad...and drives me crazy... I'm installing HP manifolds this winter, so I'll live with it until then...

[Charger RT]

put an ice cube on it and see what happens.
Tim

[John_Kunkel]

If the spring holds the butterfly open, the spring is installed backwards...the spring should hold the butterfly closed.

Valves with a counterweight stop will rattle at idle because the exhaust pulses at idle (moreso with a bumpity-bump cam) and smooths out as the rpm increases. The exhaust pulse will blow the valve open and between pulses the counterweight will hit its closed stop causing the rattle...they did this when brand new.

[FLG]

As advised earlier....

Get RID of the thing 

There are some things on these cars that there better without, this is one of them...and the heat crossover for the intake manifold is another. At the time when these were daily drivers, its was understandable...but now with gas as crappy as it is and these cars not being driven all year round, you will do much better without.