Heat riser 1978
Thread Starter
Intermediate
Joined: May 2020
Posts: 45
Likes: 3
From: Shelby Township, MI
Heat riser 1978
In which position is the heat riser block open? Vacuum to the valve pulling the rod up or no vacuum with the rod down? I changed to an electric choke thermostat and want to just keep the valve open all the time. Thanks in advance!
Race Director
Joined: Mar 2017
Posts: 11,902
Likes: 4,475
From: Virginia
It should be fail-safe, meaning it will open WITHOUT applied vacuum. It sounds like your vacuum modulator is still functional. Applying a vacuum will show you the "closed" position. No vacuum (as you would have at WOT, for example), is valve-open. The entire heat riser block can even be replaced with a valve-free spacer.
Paragon makes (will make?) a replacement. Take a look at the photo, and make sure the valve lever position matches what you expect. There are many other photos on the internet if you search for 75-79 Corvette Heat Riser.
https://www.paragoncorvette.com/c-23...eat-riser.aspx
Paragon makes (will make?) a replacement. Take a look at the photo, and make sure the valve lever position matches what you expect. There are many other photos on the internet if you search for 75-79 Corvette Heat Riser.
https://www.paragoncorvette.com/c-23...eat-riser.aspx
Thread Starter
Intermediate
Joined: May 2020
Posts: 45
Likes: 3
From: Shelby Township, MI
Thank you. Yes, that makes perfect sense. Had I actually thought about it for a few more minutes I would have come to that conclusion. Been a crazy week. LOL. I do plan on purchasing the spacer block to replace the valve and remove the vacuum actuator.
