GEM '62

I have a 1965 300HP 327 in my 62 with aluminum valve covers. When I bought the car it had a road draft tube,I now have a pcv valve in a grommet in the hole under the distributor, where the road draft connected, and the vacuum hose then routed to the carburetor. I am pulling air from the breather cap on the filler tube on the intake manifold. Is this a viable set up or is there a better method or one that will produce better results?

JohnZ

That should be a functional ventilation system, but it won't be a "closed" system; if the "flow" arrow on the PCV valve is pointing to the carburetor, it should work fine.

MikeM

If I read you right.......................

You should be okay as long as your valve is calibrated to your engine vacuum requirements.

But, you could do better if your clean air intake came from filtered air from the air cleaner and this would also allow a constant draw or vacuum on your crankcase.

This has benefits of stopping oil leaks and better scavenging of crappy vapors from your crankcase.

GEM '62

I have a filler tube that I think is from a 65, it has a cap that seals and a nipple for a hose. If I use that tube and connect into the bottom of the air cleaner that should do the trick, right?
Is there any chance of pulling oil from the connection at the rear of the engine, or does the internal crankcase breather canister prevent that?

wmf62

what you are doing is no different that what i do, except i'm drawing through the valve covers,
Bill

Frankie the Fink

What you have done is basically California option RPO-242 for the '61 cars as Tom Parsons has said. I installed it on my '61. MUCH better than the road draft tube spewing pollutants and greasy oil vapors under the car. Yes, it is an 'open' system and very 'viable'. It'll scavenge crankcase vapors just fine if you use a vented oil filler cap. I've run this way for 25,000 miles.

If you removed the road draft tube that contains your right side spark plug loom then I hope you replaced it with the '63 loom that bolts to the bell housing (see picture) and didn't leave your wires just dangling loose. Repro vendors carry the part.

The PCV valve "stuck in the grommet" technique certainly works but the original RPO had a crankcase vent hole adapter (see pic). These are VERY hard to find, expensive too. Some will tell you they are all around on old Chevy's of the era -- I couldn't find one that way. Had to pay too much from a vendor.

HOWEVER, what you have will work just fine.

A 'closed' system is nicer to the environment but more 'in your face'. Frankly, I'd leave what you have alone and be happy with it.

GEM '62

Thanks for the replies, I just wanted to confirm that my present set up is okay. Frank, I do have the vent hole adapter, but used the grommet because I found a PCV valve that installed vertically and fit the grommet, I couldn't find one that had a hose connection on both ends.

Frankie the Fink

Mine is hose on one and and screws into the carb fitting on the other end. The 90* fittings are readily available if the base of your carb has a threaded hole for it.

After some trial and error I found my 283ci motor 'liked' the Standard SIV-100/NAPA 2-9255 PCV valve.

MikeM

If you decide to go to a closed system, what you described in post #4 will work fine. That's the way '63 models were done.

Kerrmudgeon

While we're on the topic, one thing that has always eluded me with this diagram is the proper filler tube and cap that goes with it. Does it use a straight push on vented cap? Anyone have pics of the correct RPO 242 setup showing the cap and filler tube? Thanks.

Frankie the Fink

Ah - therein lies the rub!

The 270 hp solid lifter cars are spec'ed with a non-vented oil filler cap; yet the PCV system must have air intake somewhere..presumably through adding a VENTED oil filler cap (which is what I did). However, I haven't found that in print. We do know that RPO-242 did apply to dual quad carbs as the note in the AIM page above refers to the front (FRT) carb.

MikeM

In 1957, the 1st edition 283 FI and 270 hp engines were released with vented caps. Short time later, after owner (racers) complaints of oil being slung all over the engine because of blowby out the vent cap, Chevy released a non-vented filler cap for these engines.

We've discussed this before and you can take it for what it worth as it might apply to the '61-'62 Calif. option.

If you use a non-vented cap in this application, you will have NO crankcase ventilation, only scavenging piston ring blowby. I WOULD NOT set up a street system this way.

Frankie the Fink

Agree!

GEM '62

I have a holly carb. so no screw fitting, just a push on hose fitting.

Frankie the Fink

I understand - whatever works.

As soon as I added the PCV system on the '61 the first thing I noticed (besides the absence of oil drips in the garage and noxious fumes while driving) was how clean the oil stayed. The oil kept that honey color all the way to the next oil change instead of becoming that black coffee color. Interesting.

65tripleblack

How would one know this?

watson

OK, forgive me if this is a dumb question but I am a little confused. I thought that the clean air came from the air cleaner to the hole at the rear of the block. The PCV valve is fitted to the hose from the oil filler tube, sealed cap, to the carb. I believe that is the original road draft, external oiling of everything, system. Where is the PCV valve in the system that you folks are describing?

Thanks,

Doc

66jack

Just the opposite...Reverse your thought process on how air flows...

MikeM

The factory did it both ways. Doesn't really matter as long as you have a filtered air draft through the crankcase.The vacuum from then engine can pull that draft through the rear of the block/air cleaner, a valve cover/air cleaner or the oil fill tube with vented cap.

watson

OK, so the clean air comes from the oil filler tube. That means that I need a vented cap right? On my 65, the cap is not vented and the PCV valve is in the line from the oil filler tube to the carb. The line from the rear of the engine is connected to the air cleaner. I guess what I am asking about is the post that refers to a better way to do this. If I want to dry up some of the oil mist that seeps out, I assumed that I would go to a closed system. From what I see on my car, the only opening to outside air is through the air cleaner to the rear of the block. I took that to mean a closed system. Sorry to beat this to death, I am just trying to sketch out how the system should be. My car was previously owned by a real idiot. Everything seems to have been messed up. For example, the heater hoses were reversed. Considering that they are different sizes, that took some work. Now I am wondering if the vent system is also screwed up.

Thanks Again,

Doc