Join Date: Oct 2014
Location: Nashville, Tennessee
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
We called these things heat riser valves.....as said the spring kept it closed when cold so that exhaust was routed under a passage in the intake underneath the carb....it forced all the exhaust out through that passage under the carb and through the other manifold....once heated it opened and exhaust went out as normal.
They always stuck and broke and rusted and you have to keep 'em lubricated...
Use PB Blaster to free up stuck ones.....anyway I took my manifolds out and used the HO manifolds, no heat riser at all..
If you can't make it move freely from lots of blaster on hinge, the wired open is fine....I don't notice any difference, as long as you have a good working choke system..now in very cold climate sure it may help, but it only stay closed a few minutes...like a choke...