The Stovebolt Site Forums The Shop Area Engine Shop Breathers and grommets

Before I go endure 30 mins of blank stares and shoulder shrugs at the local parts store, or order 5 different wrong things from the jungle website….

Anyone know of a part # for a twist in breather with a smog tube on it…that would fit tightly in a 235 valve cover.

Or….a grommet that would fit in the twist in hole that would allow a push in breather (with smog tube).

I’m working on a PCV setup.

I don't know how far along you are on your PCV system but you may want to look at this article before re-inventing the wheel.

Not only has this guy researched the subject as it pertains specifically to Chevy 217/235/261 engines, he offers a step by step tutorial to do it yourself with all part numbers included.

He also sells a ready made kit with pre-bent vacuum lines and all the parts needed for a reasonable price.

http://devestechnet.com/Home/PCVInstall

Bring the salt shaker when you read that article! You'll need several "grains". Also, buy some stock in an oil company- - - -putting the PCV that close to the crankcase will turn your engine into a mosquito fogger! The factory system uses a standpipe that puts the PCV valve up about valve cover level.
Jerry

I’m well aware of the Deve setup and some of its shortcomings. I was afraid my question might take us down that path which is why i was intentionally vague with my question.

I’ve done a lot of reading here and have a pretty good idea what I need to do and how I want to do it. Once I’ve built it, I will post and you all can offer constructive feedback. I won’t have much money in it, and my feelings are not easily hurt.

If anyone knows what I’m asking for in the original post….I need that particular type of breather or grommet to get started.

I assume I’m looking for something roughly like this:

https://www.jegs.com/i/RPC/707/R4806/10002/-1

But can’t tell if the twist in portion would work on a 235 valve cover. Perhaps that’s all standard stuff. I don’t have a SBC in my life to compare to.

I believe the hole size and the cam setup on a small block V8 is the same as the twist-in cap on a stovebolt six valve cover, but the only way to be sure is to try it. It's possible that your local auto parts store will have the same setup, instead of doing an online order. In case it doesn't fit, it's a lot easier to get refund from the local guy!
Jerry

True. I just tend to make it a habit not to walk into the “O” or the “AZ” without a part number already looked up. It saves a ton of time and avoids the awkward conversation of explaining to the young fella manning the counter that we can’t look this up by year/make/model in the computer.

I am blessed to have a really good Napa in town. Those guys all know how to use the actual books made of actual paper. But with some of this oddball stuff, it’s still worth my effort to do homework up front. For instance, took me forever the other day just to get a 1/8 NPT to 5/16 barb fitting.

One more pertinent question….what is inside the body of the draft tube? Horsehair packing? Baffles? Both?

We ran a negative pressure on our circle track engines by having a tube with baffles in it mounted to the factory fuel pump location. Can't get any closer to the oil supply than that but never a wisp of blue smoke. Rather than engine vacuum, which wasn't much with both valves open most of the time, we had a tube in the exhaust collector with the end angled so the high velocity exhaust passing over it drew a high vacuum. Baffled tube was about a foot long, vertical, and at least eight overlapping baffles at a 45* angle. Early sbc had a baffle (they called a condenser) in the lifter gallery that was simply a smaller tube inside a larger one. It doesn't take much to draw air and not liquid/vapor but a bit of thought to do so. For sure, you and the whole neighborhood will know if it's wrong.

The draft tube I cut the top off of had baffles in it. That's how I set up my PCV system, cut the top off just below the tube that points to the ground, then welded on a plate with a 3/4" hole drilled just a hair over with a step bit. I had followed Deve's steps prior using the freeze plug but it was eating a lot of oil. With the draft tube still installed and the extra height from the block it doesn't suck any oil at all now.

I believe the draft tube has a couple of small diameter tubes inside, with holes drilled in them. We used two pieces of exhaust pipe about a foot tall welded to the driver's side valve cover on the race engines, with pleated cloth breathers about 3" in diameter attached to the tops with hose clamps. They still got saturated with oil during a race, so I cut a series of diagonal slots at a 45 degree angle in both breather pipes and welded in several downward-facing sheet metal baffles to deflect the oil while letting the crankcase vapors pass. No PCV on a race engine, obviously!
Jerry

If I were inclined to set up a PCV setup on my 235 (which I am not), I would sooner get my hands on an early 216 downdraft tube which came with an oil fill cap on top of it, and put the breather cap there, plug the bottom of the draft tube, and put the PCV valve on the top of valve cover. The hose from the PCV valve can be plumbed to the wiper fitting with a T fitting.
There are a lot of nasty watery vapors which like to collect on the underside of the valve cover. A PCV valve located on the top of the valve cover would sip that away quite nicely.

Stealing my thunder, Carl. Not precisely what I had planned, but close.

Got something in mind that ought to be pretty easy for anyone to replicate. Striving to make it inconspicuous.

I’ve seen some kits you can buy that use exhaust to pull the PCV circuit.

Putting a breather cap on the early style draft tube would require some creative welding, as the cap on the early breathers clamps around the outside of the standpipe. I'd suggest finding a trashed valve cover, either 6 or V8, and swiping the internal camlock part to weld onto a later model standpipe after removing the top plug.

The bored out freeze plug and grommet approach that's such a dumb idea down at the block would work well to insert a plug-in breather cap at the top of the standpipe. Just weld the freeze plug to the standpipe after cutting the blind plug off.
Jerry