1959 Exhaust Butterfly Valve Removal

[Frank D.]

Re: 1959 Exhaust Butterfly Valve Removal

Another thing to consider. Folks with carbureated cars that block off the heat riser intake manfold runners with fuel injection gaskets to reduce fuel percolaton MUST wire open or elminate the exhaust manifold valve or the PS. exhaust literally has no plac to go.

[Tony M.]

Re: 1959 Exhaust Butterfly Valve Removal

Leif,
Thanks for the explanation.

Have a great night to all!
Tony

[Duke W.]

Re: 1959 Exhaust Butterfly Valve Removal

Duke,
For educational purposes, what do you mean there will be very little out of right side for a minute or so?

Thanks again.
Tony

When the engine is cold the valve should be closed. Upon startup this forces all the exhaust gas to the left bank via the heat riser passage in the inlet manifold. The reason to heat up the manifold and carburetor with hot exhaust gas is to promote fuel vaporization for good drive off characteristics after a cold start. This is particularly important in very cold weather, but most don't drive their vintage Corvettes in very cold weather so this heat riser function is usually not necessary, and forcing the hot exhaust gas through the heat riser heats up the carburetor and promotes fuel percolation.

As the manifold heats up the thermostatic coil expands and opens the valve. Normally on a fully warmed up engine the valve should be full open at idle. Some don't open all the way, but the shaft is slightly offset so as exhaust flow increase once the car starts to accelerate the higher exhaust flow rate will force the valve full open.

Some go so far at to remove the butterfly valve from the housing or replace the whole thing with a FI spacer that is simple a partially machined housing that lacks the valve. FI systems do not need a heat riser since they inject fuel at the port or directly into the cylinder on modern Corvette engines.

Duke

[Tony M.]

Re: 1959 Exhaust Butterfly Valve Removal

Duke,
Funny, I never knew about the exhaust runner in the inlet manifold!!! Wow, learn new things everyday! Next lesson, I want to truly understand my dual quad setup!!!!

Duke, I have owned my 59 and previous 67 for a total of 35 years. I also own a Viper and Prowler. I have told my wife numerous times over the years that I would be perfectly happy owning the two Chryslers. Now, after spending 20 days working on little things that bothered me on the 59, the two Chryslers may not see the summer this year! They may be for sale next year!

Just to say, I am enjoying my Corvette again and want to improve it everyday!

Thanks to all for the help.
Tony