The Stovebolt Site Forums The Shop Area Engine Shop 250 with 292 Manifolds

I needed to replace the manifolds on my 250 and bought a manifold set from a 292 industrial engine. I had it home and installed on my engine before I realized that it had no provision for a PCV valve and no heat riser in the exhaust. It also had a larger exhaust outlet, but I can deal with that. And I’m not too concerned about the heat riser. It does concern me that it has no port to connect the PCV line to.
Suggestions? Thank you.

Easy enough to drill and tap a hole in the intake manifold for the PCV connection. Cast iron is pretty easy to drill and tap.

If you don't want to try to drill and tap the intake for a PCV fitting, make a 3/4" thick aluminum spacer between the carb and the manifold, and drill and tap it for a 3/8" NPT brass vacuum nipple.
Jerry

Does it have heat under the intake since there is no heat riser valve? Without a heated intake, it will run really bad till it gets enough heat in the intake to vaporize fuel. I went down that road running three carbs on a home made intake, it took a long time for a mild steel intake to heat up and run right.

The carb spacer is a good idea, it will spread the oil vapors to all six cylinders instead of just the center ones. Drilling the intake and threading would be easy also, it only takes a few threads and some loc-tite to hold the fitting.

Thanks for the advice. 👍

Joe, I took the manifolds off of the engine and separated them. I wanted to know if there was heat going to the intake, and there is. There is a threaded port on the intake that was plugged. I removed the plug and found a hose adapter that I can screw in there to run the PCV hose to. SO, I think it will work out.
Thanks again for all comments.

Sounds like you are good to go with the benefit of larger exhaust pipe. Run the bigger pipe to the muffler, then scale down to 2 for the tail pipe. Thats how most of the HP cars were made, by the time the exhaust gases exit the muffler, they are cooled down and don't need the bigger pipe.

Thanks! I got the PCV line ran to the adapter on the intake. Carburetor cleaned and mounted. Linkage connected. No exhaust pipe yet. But did (finally) get it running on an auxiliary fuel tank. 😎. Lots more to do, of course, but still I’m pleased with the progress. Here’s a short video of this engine running for the first time in 26 years (according to the previous owner).

Short video of first time my 250 is running in 26 years

Cool. Sounds like an airplane.

Sounds really good. It's amazing how these old engines can be brought back to life.

One precaution- - - - -that open pipe into the valve cover will allow dust to be drawn into the engine by the PCV system. Either plumb that pipe to the "clean" side of the carburetor air filter, or add a filtered breather like this one:

www.ebay.com/itm/194233850603?

Jerry

It’s true. Those old Chevy 6s are hard to kill.

Thanks Jerry. With the air filter installed that hose is routed to a breather filter.