The Stovebolt Site Forums The Shop Area Engine Shop PVC setup for a 235?

Has anyone thought of/done getting rid of the draft tube on the 235 and convert it to a PVC setup. I have been thinking of doing it, but don't know if I would need a baffle in the valve cover, or make something to put it in the draft tubes place.

Ideas??

Brent

An old-timer broke down in front of our house in a short AD Chevy bus which he converted to a camper. He had a 261 with a PCV valve in the valve cover and no breather tube. I wasn't sure if it was stock but it seemed like a good idea.

He broke down because of a busted fuel pump which he dismantled and repaired with my tools. A check valve in the new fuel pump had popped loose. I was really impressed.

You cold retrofit for a PCV but why? True, emissions are higher with an externally vented engine but there are relatively few of these on the road anymore. If you want to go the PCV route, you need a source of fresh air to the engine and a vacuum source to pull the vapors. Small block chevy's typically have the PCV connected to one valve cover going to a vacumm connection on the carb/intake manifold and a fresh air hose connected from the air filter housing to the other valve cover. You need this "circulation loop" for the concept to work properly. I think someone mentioned putting the PCV valve in the old draft tube location and fresh air to the valve cover. That should work.

I recommend conversion. It saves your crankcase. With a PCV you always have the vapors being scavenged and it helps keep the oil free of moisture and aromatic contaminates. Since the crankcase is under partial vacuum instead of pressure the contaminates in the oil boil off faster. You also don't cause a stink behind you. It costs nothing but the parts, and its benifits out weigh the drawbacks (none).

You can use a modern PCV valve. Try one from a similar size engine, like a Jeep 4.0L or a Chevy 4.3L. Cut off the road draft tube leaving the top part, fill the hole, and get a rubber grommet the size of the PCV valve to fit. Install it in the hole. Run a vacuum rated hose over to the intake and tee it into where the vacuum wiper hookup is. If you have a vented valve cover replace it with a regular one but use one of the vented caps or drill a hole in the valve cover for a hose to the air cleaner. Start it up. You may need to richen the idle mixture a little bit but other than that you are done.

The reason you use the road draft tube parts is because there is a baffle to keep splashed oil in the engine. If you run it to the valve cover you will suck oil up into the PCV system and have problems.

Thanks, the 235 that I pulled recently has a make shift set up, The draft tube was plugged, had a tube that was tee'd from another on the valve cover, then to the air cleaner. The vents were soldered shut and a ventable oil fill cap. Kinda ugly setup. It had no vac. source except what the carb was giving. Next to none.

i have done this and it worked great. all i did was as mentioned above. cut the road pipe and go to napa or somewhere and find a pcv grommet the same diamater as the pipe. my 235 came stock with the breather cap in the valve cover that worked great. the idle instantly evened out (it was a tad lopey before) and the steam coming out the pipe is gone. no jetting no fuss no muss. plumb to side of intake as described.

The Forward Control Trucks,( those UPS, roach coach style trucks)came with PCV from the factory from about 1948. The reasoning was these trucks were used in delivery and therefore spent a lot of time idling or in low speed operation. The road draft tube needs some speed in order for it to work properly.

Does anyone have pictures of any of the setups that were mentioned? Sounds like an interesting idea and while I can mentally picture it, any photos would be a big help... thanks!

sorry...sold the motor...