Tiberian Fiend

I bought an NOS Edelbrock 7111 intake manifold for my '67 Cutlass 330 and the box says it supports a 330 engine, but it seems like the port on the manifold for the heater control valve is too large. I bought one for a '68 350 from a parts house but I'm waiting for it to come in to see if it fits. Which heater valve is supposed to go with this manifold? What problems may I face using the one for the 350 engine?

Magna86

Just eliminate the heater control valve. You can buy a threaded adapter with a barbed nipple on it to attach the coolant hose. You can find them at the parts stores in the hotrod section of just order it from Summit or Jegs.

joe_padavano

If the threads in the intake are too large, you can simply use an NPT bushing to adapt the original valve.

quaddriver

yeah what he said, the valve does not even have to be on the engine....just connected to it somehow or another

joe_padavano

That's an excellent point. When I got tired of replacing the crappy heater valves on my 307 that failed every month or so, I replaced it with the Chevy-style valve that splices into the hose instead of screwing into the intake. The Chevy valve is plastic and never corroded or leaked, plus replacement is simply two hose clamps and not the inaccessible 1 1/16" hex.

Tiberian Fiend

The hole is 1" and the heater valve is 3/8". I'm having a lot of trouble finding a reducer with those dimensions. I'm guessing I'll have to use two, which I really don't want to do, since the more joints it has, the more places there are that can possibly leak.

joe_padavano

Sorry, but you are making this much harder than it needs to be. First thing is you need to understand the dimensions of NPT threads. The 3/8' is the INSIDE diameter of the heater valve port and is unrelated to the thread size. The threads on the valve are either 1/4 NPT or 3/8 NPT. If 1/4 NPT, the diameter at the small end of the threads will be 0.48". If 3/8 NPT, the small end will be 0.61".

If the opening in the intake is about 1" as measured, that's 3/4 NPT thread.

Here's a 3/8 NPT by 3/4 NPT bushing.

Here's a 1/4 NPT by 3/4 NPT bushing.

Tiberian Fiend

I took the valve into Lowe's and tried it on their size testing display, and it's 3/8". I'll have to give that one you pointed out a try. Thanks.