Vapor Lock - 427/400 Heat Riser?

[Jack C.]

With the engine cold, the heat riser is spring loaded closed correct? I noticed this morning that by manually pushing it open it does have some drag on it (rusty). Should it function nearly totally without binds or should I try to wire it open and see if that helps to eliminate my vapor lock problem?

[Stuart F.]

Re: Vapor Lock - 427/400 Heat Riser?

Jack;

Your assumption is correct. A proper functioning valve should move freely to the down "open" position, then spring back up to the "closed" position. Certainly, wiring it open is worth a try to see if it helps your situation, but it is not necessarily a cure all. I would try (possibly this fall) to work on freeing it up with some of the penetrating/lubricating oils available for this purpose from your Chevy dealer. Others might chime in with the specifics on the oil.

I wire mine open during the hotter months, but find better warm up and drive ability with it functioning properly during the cooler months.

Stu Fox

[Jack C.]

Re: Vapor Lock - 427/400 Heat Riser?

Thanks, I will try and free it up and see if there is any changes to my situation. There is surely a slight bind that needs to be worked out.

[John D.]

Re: Vapor Lock - 427/400 Heat Riser?

jack,

When I wired my heat riser in the open position all my hot start problems went away immediately. It helps prevent fuel percolation in the carb bowls.

[Jack C.]

Re: Vapor Lock - 427/400 Heat Riser?

Thanks, I will do that today and report back in. This is the only thing I haven't tried so far to cure this problem.

[Jim T.]

Re: Vapor Lock - 427/400 Heat Riser?

Your right side exhaust system would benefit. Usually the muffler is the first to go from rusting.
Course this depends somewhat on how the car is driven.
Wired open systems generally create less problems.

[Jack C.]

Re: Vapor Lock - 427/400 Heat Riser?

I just wired the heat riser open and let her idle with the hood closed. Underhood temp seems lower, I can actually touch the fuel lines at the carb without burning my fingers. I'm taking it out this morning for a run and will report back later.

[Richard M.]

Re: Vapor Lock - 427/400 Heat Riser?

You may also want to try avgas(100LL)or race gas, these fuels contain no ethanol and are formulated to have lower Reid vapor Pressure(RVP) to reduce the chance of vapor lock. Good Luck! Richard

[Jack C.]

Re: Vapor Lock - 427/400 Heat Riser?

Thanks, I do run 100% 100LL. Back from my ride and no vapor lock.

[Andre R.]

Re: Vapor Lock - 427/400 Heat Riser?

Hey All, The best solution is to cut the butterfly plate off of the rod with a dremel or similar tool. 100% correct look on the outside, predictable function on the inside