I know the earlier cars had a road draft tube that was used to vent the crankcase. It connected to a hole in the block next to the oil pressure gauge connection behind the intake manifold.

From reading on the forum, I got the impression that some later cars had a fitting that went in that same hole, replacing the road draft tube, that allowed the connection of a PCV valve, that then had a rubber line going to the carburetor. I've tried looking for that fitting at several of the Vette parts suppliers, and find nothing. Did I dream this all up?

 

You did not dream this up....here is the fitting and also how things are connected on an early C1. 1961 was the year the RPO-242 (PCV "California" option) became available. The fittings, although once numerous, are hard to find and command a premium price - $50 unrestored and $75 cleaned up and replated -- and that is IF there are any available.

Soooo.....some have just used a rubber grommet and metal pipe instead and it works just fine.....and that is shown in the third picture. Paragon lists the PCV fitting but they seldom have them in stock: https://www.paragoncorvette.com/p-34...vent-tube.aspx

 

Nope.
Beginning with 63 models (62 models in CA), that hole in the rear of the block (ONLY small blocks) was used for SOME variation of PCV system. Not all engine configurations had the PCV exit source at the rear hole. Some had the PCV valve source located at the oil filler tube at the front of the intake manifold. But, the design of the system was the same-----fresh air in (somewhere)-----------vapors sucked out (somewhere).
The engines that used the rear hole for an adapter fitting for the PCV valve were the MOST common. Thousands, maybe millions, of small blocks had this fitting which was attached EXACTLY the same way as a road draft tube----------with a long 1/4-20 bolt, and a hose which was connected to a PCV valve that was connected to a manifold vacuum source, usually at the base of the carb.
This fitting should be easy to find. Also, the bolt that was used to secure it at the rear of the block, had a fiber washer under the head of the bolt to seal the hole in the fitting.
I have a picture somewhere. If I can find it, I'll post it.

Even though this question is obviously directed at 56-67 Small Block V8s, the other Chevy V8 engines used different locations for crankcase ventilation. The BBs ALWAYS used a hole in the valve covers. The W-engines (348-409s) had a hole in the rear of the intake manifold (just in case you want to stuff a 409 in your 57 Vette someday ).

Tom Parsons

 

Here is the crankcase PCV fitting "bolt kit" from Paragon that Tom mentions:
https://www.paragoncorvette.com/p-34...-bolt-kit.aspx.

What is harder to find is the correct '61 283 ci PCV valve....it is NOT the same as the '62 PCV
valve used on the 327 motors. It is made of "unobtainium" and I've never come across one.

Frank

 

Thanks for the quick responses. I didn't realize that fitting was so precious, at least to Paragon. I think I'll rig up some other type of fitting -- not worrying about correctness, it's a 327 in a street rod.

 

Then get one of these off eBay and "soldier on"!
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p5197.m570.l131 3&_nkw=pcv+conversion&_sacat=See-All-Categories

Or, cobble your own rig together from similar parts and save some bucks.
Your call. But, bear in mind you will need a vented oil filler cap to allow the correct flow
of air once you install the conversion kit.

 

No problem, the valve covers are vented already. I just thought I'd be a little more "environmental" and replace the road draft tube with a PCV valve. Yeah, I know it sounds weird....everything vented to the atmosphere. I have a feeling the PO either didn't know or didn't care.

 

You guys are the greatest! How many times has this been dealt with here, and you still have the patience to do it all again. Good on ya mates!


My 68 buddy calls me everyday with elementary questions about his car, and sometimes I just say "Read the dang book".......sometimes!

 

Hey!! You're talking about my "BABY"!! Here's some pics of what I think you're looking for.....in '62 it was RPO 242