Heat Riser Open or Close Direction (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Steamer

SILVER Star
Joined
Jul 20, 2009
Threads
54
Messages
2,156
Location
Miami, FL
My stock exhaust manifold's heat riser/flapper works fine. Had the manifolds blasted, cleaned up, and treated with a coating. And of course I put the manifolds back on and just now putting the bi-metal spring on. I can figure out which way to put the spring, if I just knew what direction opens or closes the valve. Does anyone know off hand which direction it should rotate when warmed up?
I can't believe I did this again. I'd hate to pull the exhaust pipe off to look up in there. Any help appreciated.
 
Well I found this pic of a 2F manifold with 3 studs. My F.5 has two studs but I’m guessing the flapper action/rotation would be the same. The flapper in the pic looks like it is in the, “heat up the intake” position. So, if that’s correct, then looking from the front, a clockwise rotation would close off heat to the intake manifold.

This is all that’s holding up my Sniper first start up. So, I think I’ll go with it. If someone sees it’s wrong, let me know and I’ll change it.

ExhstFlpr 01.jpg
 
No idea if my 67 would be the same direction but, don't see why it wouldn't be. This is on the rear of the manifold, and you can see the C for Cold and H for Hot on the bracket that stops the rotation.

ab-engineHeatRiserWeigt-c.jpg
 
Ah hah! That makes sense now. I have it backwards. From the front, it rotates counter-clockwise when it warms up. I'll flip the spring in the morning. Thank you Sir! 🍺
 
This link should illustrate the arrangement for your 1972:


I have a 74 but "Yes" that link with your pics did it. Your pic of the spring in place corrected another mistake I was making. I was believing that the spring un-coiled when heated. I was wrong. It coils up tighter when heated. Just checked with a heat gun.
All clear now. Thank you!
 
I'm on the original spring that came with the new SOR manifold I got in 2000. Fairly rusty but seems to be working. It was fun trying to move a piece of sand cloth around that spiral to clean it up.
I'd be very interested to find a new alternative spring. What do you suggest?
 
@Steamer


Things have changed regarding price and vendor since I posted this, but if you do a google search on
Omix-Ada 17625.02
you will find a number of vendors if you click on shopping.
 
"Ordered" Looks like I'll just have to bend the hook on the end. Expected delivery 3-5 days from Amazon. Thank you sir. Never thought I'd have a chance at replacing it.

"EDIT" thought I'd add the pic

Omix-Ada 17625.02.jpg
 
Last edited:
Well the new spring got lost in shipping, then found, then finally delivered.
I trimmed some of the excess length, bent in the hook and installed. There's only two positions to put it on which are 180 deg from each other. One way didn't provide enough tension to hold it in the "cold position" while cold, and rotating it 180 put plenty of tension on it but when cranked up, the engine had to come up to full temp to move to the "hot" position and even then there was barely enough tension to hold it there. In fact I'd call it 98 percent held closed off in the hot position.
So I ordered another spring and this time did no trimming but bent that 90 bend back straight and put the hook bend on the very end. This gave it about another 45 degrees and had less tension holding it in the cold position. This worked out very well. With a cold start up and as the engine temp rose, the flapper was about half way closed at 140 deg, just barely closed at 160 deg, and closed with tension on it at 170 deg. I'm figuring that's pretty good.
Anyhow I'm pleased with it and thank you "73fj40" for the info.

Bi-Met-Sprng 03.jpg
 

Users who are viewing this thread

Back
Top Bottom