There are two threaded holes on the thermostat housing on my 1984 T/A 305 engine. I know their purpose. Does anyone know the hole sizes & are they pipe threads And where I can purchase them?
Why - the egr valve failed (already disabled it by placing a ball bearing in the vacuum hose) & heat riser is failing. I want to remove the egr valve (i will fabricate the cover) & cut out the butterfly from the heat riser. Thus I can plug one of those holes and route a vacuum hose from the carb directly to the vacuum advance.

 

I believe they are pipe thread. 'Sorry I don't remember the size. You can buy the EGR cover (comes with gasket & new bolts). No need to fabricate one...

 

3/8" pipe.

Parts store.

Cheeeeeeeepest way to eliminate the EGR is to make a plate out of maybe 12 ga or thicker aluminum stock, and use the "spacer" thing it came with to hold it down. Easiest is probably what T. L. said.

For the heat riser, go here. https://www.thirdgen.org/forums/tech...ml#post6447424

 

3/8" and 1/2" NPT.

 

Thanks for the info. Much appreciated.