223 exhaust heat riser valve

[Daves55Courier]

I dont have good parts to make it operative, so for the time being, I left the valve out of the exhaust manifold and just put a long bolt thru the holes so it wont leak exhaust there.
If I leave it out, wouldnt there be a small amount of vacuum loss to the distributor and also wouldnt the continuous rising heat also evaporate some of the gas coming into the carb throat?
Would it be better to cut a piece of sheetmetal and sandwich it in between the exhaust and intake manifolds to close off that big opening permanently? There doesnt seem to be a problem warming up the engine without it.
Any thoughts?

 

[277 I6]

there will be no vacuum loss dont put a plate between the manifolds or you will lose some of the warmup

 

[Daves55Courier]

I can pull out the manual choke cable 1/16 of an inch and let it run for a few minutes that way in cold weather for warmup. It doesnt seem to need ANY quick warmup in warm weather, so no choke is required.

I'm more concerned with driving performance after the engine is warm without the valve installed.
Would constant exhaust pressure open to the carb affect mileage or possibly cause vapor-lock.
Since there would be no separation between exhaust and intake, why wouldnt the carb vacuum port just suck exhaust gases rather than pull the distributor vacuum diaphragm. Easiest path would be exhaust wouldnt it?
Its all just theories in my head.
More input on there issues please?

 

[Fred]

There is no hole in the intake where the exhaust gas can get in. There is a cavity cast into the intake manifold under the carburetor that exhaust gas goes into to heat the intake, but it does not open into the intake. The exhaust flap is just there to direct more exhaust heat up toward the intake when it is cold. If the exhaust gasses ever do cause enought corrosion to burn a hole into the intake your engine will run like crap. This happens on aluminum intakes sometimes.