1968 327 PCV system - Chevelle Tech
Engine AdvertisementGeneral Engine Discussion.

LinkBack Thread Tools Search this Thread Display Modes
post #1 of 4 (permalink) Old Feb 21st, 08, 8:29 PM Thread Starter
Lifetime Premium Member
Join Date: Dec 2001
Location: ND
Posts: 436
1968 327 PCV system

Can someone with an original 68 327 tell me how the factory hooked up the PCV system? I saw a set of supposed L79 valve covers for a 68 that had no holes for the system, so am curious as to how GM had the system designed.
Steve67L-79 is offline  
Sponsored Links
post #2 of 4 (permalink) Old Feb 21st, 08, 11:05 PM
Boldly procrastrinating
Tom Terrific II
Join Date: Oct 1998
Location: Glendale, Az
Posts: 25,122
Re: 1968 327 PCV system

'68 L79? I didn't know they were made in 68. better check on that.

engines with solid valve covers had a block that had a breather hole cast into the back. These engines have a can baffle mounted in the valley. the other end of the system was the oil fill tube at the front of the manifold. if the PCV was at the back the oil fill tube had a vented breather cap. If the PCV was screwed into the side of the oil fill tube it had an airtight cap and the inlet air came from the bottom of the air filter housing, a large diameter hose went to the breather hole at the back of the block.

Both work to ventilate the engine, but the later deal with the PCV screwed into the oil fill tube had filtered air being fed into the engine.

Tom Terrific or Terrible Tom, depending on the phase of the moon, passing cosmic rays or other factors not fully understood except by my wife.
Tom Mobley is offline  
post #3 of 4 (permalink) Old Feb 21st, 08, 11:37 PM
Lifetime Premium Member
Join Date: May 2004
Location: Grand Rapids, MI
Posts: 404
Re: 1968 327 PCV system

Check out this thread: 68 L79 Chevelle

Take a look at the pic- it sure looks to me like a hose is going into the valve cover behind the alternator.

'68 Chevelle- 396/TH400
'93 Corvette Ruby Red 40th Anniversary Edition
'55 Chevy 210 2-door sedan Gasser project

Last edited by midshark; Feb 21st, 08 at 11:52 PM.
midshark is offline  
post #4 of 4 (permalink) Old Feb 22nd, 08, 7:37 AM
Senior Tech Team
Join Date: Sep 1998
Location: Mustang, OK USA
Posts: 11,480
Re: 1968 327 PCV system

ALLLLLLLLLLLLLLLLLLLLLL 68 small block engines DID NOT have the hole in the rear of the block for crankcase ventilation.
AGAIN, POSSIBLE, BUT EXTREMELY UNLIKELY. The reason is specifically because 68 is the year that crankcase ventilation changed from the rear of the block to the valve covers and that configuration would have been the same for all engines at the beginning of 68 production.
As I commented elsewhere, I personally have seen and owned a 68 327 that had the boss in the rear of the block for the crankcase vent hole, but it was not machined, now was there a boss on the underside of the bell housing flange which would be required to machine a hole for the passage into the rear of the lifter valley.
Therefore, beginning in 68, on all small blocks (BBs began in 65), the crankcase/PCV setup was accomplished with holes in the valve covers. Also, 68 was the LAST year for an oil filler tube at the front of the intake manifold. The 69s got an oil cap in one valve cover (BBs always had an oil cap in one of the valve covers).

Tom Parsons
TC# 474
#3 FOREVER!!!!!
Light travels faster than sound. That is why some people appear to be bright until you hear them speak. (unknown)
DZAUTO is online now  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Old Thread Warning
This Thread is more than 3381 days old. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
If you still feel it is necessary to make a new reply, you can still do so though.

Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome