Y Blockers, I have been reading the discussion about the heat risers between the crossover pipe and the right exhaust manifold. I checked mine out on my '54 F-100 and noticed that it barely opened up after the truck was warmed up and driven for awhile. Does this mean exhaust from the left was going across the intake to the right side as it is supposed to do as it warms up??? Why doesn't the bi-metal spring thingy work? The stud holding the spring is badly rusted, would this prevent heat flow to the spring? How does this affect my peformance? Should I block the riser open and deal with cold weather starts? Can we still buy heat risers at NAPA, etc?
Thanks for past and future knowledge, Abe '54 F-100

 

Abe,

After talking to people more knowledged and expierenced than I, It is thier opinion that Ford engineers designed the carburetor to always have a flow of exhaust through the crossover even when fully warm. This enabled them to run smaller jets and reduce the accelerator pump volumn which would help fuel economy. The heat helps atomize the fuel droplets. If the damper is removed you will have to adjust the acc pump and increase the primary jets to prevent flat spots cauysed by a lean condition. When you "Hot Rod" a engine you normally play with these items and that is why the problem only occurs on stock systems that have the valve forced wide open or removed. On a stock system a fully heated damper will not be fully open and when the rpm increases the valve will open more (a result of the exhaust pressure against it) to decresae the amount of crossover gases. I will not take credit for this but I feel it is logical and probably correct.

Charles in Pensacola

PS if you had of responded to the original post it would automatically cycle to the top and everyone else would receive e-mail notification of a update. Not criticizing just trying to help your forum manners. Don't take this the wrong way we all make mistakes I know I have and still will