Heat Riser Movement
Thread Starter
Intermediate
Joined: Mar 2019
Posts: 43
Likes: 3
From: Knoxville, TN
Heat Riser Movement
Guys, searched threads but could not find an answer, how far should the heat riser butterfly open? Mine only moves about 1/4" which I don't think is correct? Shouldn't it open 100%?
Thanks, Andy
Thanks, Andy
Team Owner
Joined: Aug 2007
Posts: 58,061
Likes: 7,145
Army
That is NOT correct, the flapper should go vertical unless somethings corroded/frozen up....hit it with some PB-Blaster or better yet force it open then wire it in that position. You're running with a a restricted exhaust as it is now.
Last edited by Frankie the Fink; Mar 22, 2020 at 12:19 PM.
Thread Starter
Intermediate
Joined: Mar 2019
Posts: 43
Likes: 3
From: Knoxville, TN
Thanks again Frankie, knocked the crap out of it, seems loose now. Do you think this would have caused any "exhaust vibration"? riding around? All the exhaust from the PS cylinders would have had to have been going through the engine to the DS exhaust?
Race Director
Joined: Apr 2005
Posts: 11,265
Likes: 2,131
From: Bowling Green, Kentucky
Andy:
Many of us wire it open with stainless wire, or replace it with a spacer (FI cars used a spacer....which you can buy). You living in Tennessee you don't really need it for cold weather warmup.
Larry
Many of us wire it open with stainless wire, or replace it with a spacer (FI cars used a spacer....which you can buy). You living in Tennessee you don't really need it for cold weather warmup.
Larry
Thread Starter
Intermediate
Joined: Mar 2019
Posts: 43
Likes: 3
From: Knoxville, TN
Car seems to idle much better, haven't taken it for a test drive yet.....but I'm positive it will run much smoother. Question now is do I need to go back through my timing, vacuum checks.....would this valve have affected these settings?
Thanks Guys
Thanks Guys
Team Owner
Joined: Aug 2007
Posts: 58,061
Likes: 7,145
Army
Unless you changed the tune-up parameters to try to compensate for the restricted exhaust somewhere along the line - you shouldn't need to touch anything...
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Race Director
Joined: May 2000
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Just use SS safety wire to hold it full open. I have no idea which engine you have or how it is tuned, but the heat riser has no effect on the best setup. It's purely for good start off drivability after a cold start in cold weather, but contributes to the percolation problem that many experience in warm to hot weather. At worse if you do a cold start in cool weather and drive off immediately you might get a little start-off stumble, which should go away as the engine warms up.
Duke
Duke