Am in the process of doing many things to the Vette at the moment...new Edelbrock intake (getting rid of EGR option as Edelbrock carburetor does not support it), Dynomax ceramic coated headers, hi-heat spark plug wires, Bosch platinum spark plugs, new radiator hoses, and yes, new heater hoses (the molded kind).

Now, I know there have been a lot of threads concerning the shut off valves that keep the heater core isolated during the summer months, however I have not been able to find any. I know, for instance, that the interior dimensions of the hoses are 1/16" smaller than the nominal sizing of the hoses (5/8" & 3/4"). So, what size valves will work for the isolation, what do I call them when looking at the fresh faced kid staring at me over the auto parts store counter, and where did you all find yours? Am I looking in the wrong place? Should I be visiting my plumbing supply company?

HELP...I'm tired of beating the bush that everyone else has beaten before!

Mark, I just did this a couple weeks ago. The PO had put a butterfly valve (lowest cost $8) in some time ago for this application. I'm not sure how long it has been in, but it was showing surface corrosion and most important it was not providing tight shutoff. I put in a manual hand screw down type valve (approx $15) with great tight shutoff. You can get it at NAPA or any local auto parts store. The size was 5/8". I told them what I was looking for and we paged through the manual heater valve section of a book and we picked it out from there. The tight shutoff provided a large improvement in my vent temperature into the car.

There's a nice factory part you can get from NAPA. They are sized by hose size, so ask for 5/8, if that is the hose you want. Joe

I found a very inexpensive way to choke off my water flow through the heater core---I removed the return heater hose where it connected to the intake manifold and inserted a rubber "cork" shaped stopper (purchased from hardware store for about $.25) into the heater hose--stopper must be a snug fit to the inside of the hose. I pushed the heater hose back on to the intake manifold fitting and retightened the clamp--this reduce the temp. inside my car tremendously. There is no danger that the stopper will be pushed into the intake maniflod because the fitting had a metal surface (shaped like a flat washer) at the face of the fitting--the stopper bears against this solid surface and seals off the hole in the center. I'm not worried about removing the stopper later (although it shouldn't be a problem doing so) since my heater does not work at all in the cold weather so I plan to add an electric heater next winter.
Thought I would share my story with others with the same problem looking for an easy solution.
79vetteguy (Mississippi)