The Stovebolt Site Forums The Shop Area Engine Shop Factory PCV

I was at the scrap yard recently when I spotted a 'bolt with a powerglide in the corner. What really caught my attention was, no draft tube and what appeared to be a factory PCV. The valve cover was a center fill type, it had a hose fitting about 3/4 of the way back that probably went to the air cleaner. (which was gone) It also had a hose fitting about 1/3 of the way back that I'm guessing went to the pcv and another fitting screwed into the leg of the intake. It all looked factory done to me. I've never seen a bolt set up this way, if anyone else has, I'd sure like to know. Next time I'll try to get some pics.

The factory didn't install PCVs till 63-64 IIRC. They were required to be installed back to 1952, in CA anyway. There were several kits available for installation, this is probably what you found.

Larry

Was this Bolt A GMC by chance?

No, Had Chevrolet on valve cover. Had casting number 3836848 on head, telling me it's a 56 model Chevrolet. I didn't get castings off block, since they're covered by motor mounts.

PCV systems began being advertised in AD literature (Forward Control Models) prior to 1954 and figure prominently in many 261 applications. They were offered as optional equipment on some models where the truck was used in quick stop/start or delivery service. I have owned two original 1954 (one 261, one 235) versions that had the enclosed draft tube to manifold to valve cover to air cleaner set-up. The 1954 Salesman Data Book lists it as option group 217 for series 3100-6800 in a variety of combinations. The engines section shows the one in my photos on a 261 Series 6000S-6000.
These are some pictures of one from a 1954 235 (2-ton truck).

http://good-times.webshots.com/photo/2040221380102454676LuspIx
http://good-times.webshots.com/photo/2093853490102454676PxCyoF
http://good-times.webshots.com/photo/2915250570102454676yzsJst
http://good-times.webshots.com/photo/2620193000102454676PXNGMi

As posted by Brad:

A PCV type of "ventilation" system was first used as standard equipment by Chevrolet in 1948 on the model 3742, a Forward Control Delivery Chassis, updraft carburetor: crankcase ventilation: "closed system, vacuum operated" (1949 description). This was not available on COEs (standard or optional) at that time.

Positive Crankcase Ventilation (by that name) was an option on COEs and some/most standard-cab large Chevrolet trucks by 1953.

In 1954, PCV was optional on all sizes of trucks with either the 235 engine or on trucks that could have the optional 261 engine. In 1954, the 261 engine was an option only on 1.5 and 2.0 ton trucks; and, the PCV option was a separate option (not necessarily installed with the 261 engine option).