Hot Rod Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
36 Posts
Discussion Starter · #1 ·
I’m rebuilding a 67 327, cast# 3892657, I think it’s the A.I.R system, has a hole in the back of the block that connects to hoses and smog pump. Does an aftermarket intake cover this hole? It has a 2 bbl and I don’t plan on reusing it. Or do you block it off with something. I’ve done some 350s but I don’t recall seeing this stuff until now. Advice would be welcomed.
Thanks and have a blessed day.
 

·
Registered
Joined
·
3,847 Posts
I think that is the PCV. The valve goes in line. Fresh air is supplied through the oil fill tube vented cap.
 

·
Registered
Joined
·
14,207 Posts
It’s the location of the old road draft tube that vented the crankcase to the atmosphere in the good old days. As emission requirements were applied these older engines had the draft tube removed and a rubber fitting installed that fit a Positive Crankcase Vent system that would include a PCV valve and sufficient hose to connect the rubber fitting to a vacuum source to the intake manifold. Early production models also sourced blow by from the road tube location, but that was closed off an phased out in-favor of sourcing from the rocker covers.

I an not aware of the AIR system ever intersecting with the PCV. The AIR delivers fresh air into the exhaust stream to complete the combustion of unburnt fuel into CO2 and water as well as finish off CO into CO2.

The early days they kept up the pretense of needing to pull fresh air into the crankcase so the oil filler vented to atmosphere finally a second hose to the air cleaner and the oil filler tube was eliminated. Most everybody eventually figured out that no fresh air was needed.

Bogie
 

·
Registered
Joined
·
233 Posts
The a.I.r system did not come out until 1968 unless you had a california car which would have been in 1966.your engine had a steel tube shoved in that hole and it ran down beside the bellhousing.

Sent from my LM-X420 using Tapatalk
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #6 ·
I just need to know what to do with the hole. (OMG I’m 14 again) will an aftermarket intake cover it or what has been used to plug it?
616890
 

·
Registered
Joined
·
3,847 Posts
I am not an expert but some restoration project might really want to have that AIR system.
You can remove all of it but would need to replace the exhaust manifolds.
The hole in the rear of the block won't be covered by the intake.
You do need a crankcase ventilation setup of some sort, even if it's just a breather in each valve cover.
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #8 ·
This is not a restoration. It’s getting headers and a different intake, heads, etc. I’ll vent the block in the valve covers. Maybe use a freeze plug?
 

·
Registered
Joined
·
3,847 Posts
Not sure if the ID of the hole is machined.
There is a bolt that holds a fitting in the block---might be able to make a plate with a gasket.
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #11 ·
The link from RWENUTS is the fix I was looking for. Thanks y’all for the tips. Anyone remember the valve covers that had a square breather baffle that angle up from the side, cast aluminum stuff, I saw them on a couple of rat rod picks.
 

·
Registered
Joined
·
5,645 Posts
Sure do!
I used one on an Offenhauser 6 cylinder valve cover A couple years ago.
summit sells them.




and more.



 

·
Administrator
Joined
·
9,902 Posts
Did this 327 have a canister in the lifter valley (under the intake) for this hole at the rear of the block? GM had this canister there to separate oil from the vapors so the oil was not blown out the road draft tube or sucked up the PCV when that was used.. If an aftermarket intake is going to be installed: Some intakes will not fit around the cannister. Cannister is removed. Plug hole with cup plug of proper size.
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #14 ·
Yes, I removed this also. If I put breathers in both valve covers that should be plenty of vent??? Do I need a pcv valve too?
 

·
Registered
Joined
·
4,354 Posts
No. PCV was an emissions and stench thing. An open breather can give off an odor that many find offensive. PCV introduces oil vapor into the motor - there is not a good reason for that ever, other than to eliminate the smell and the emissions that come out of the crankcase. The PCV port run to a catch can is more than adequate to stop any oil emissions and will slow down the odor as well.
 

·
Registered
Joined
·
425 Posts
I’ve not experience the open breather producing an order. Unless your referring to an engine that has an measurable amount of crank case blow by. I see more cars that use a valve cover filter and a connection to the bottom of the air cleaner via a hose to the valve cover. Without anything to vent the engine oil leaks are sure to show up. A PCV is a somewhat controlled vacuum leak as far as your carburetor and intake is concerned. In 1965 chevy had a fitting that substituted for a PCV that had a small hole sucking in crank case vapors just below the rear on a WCFB base. I seem to recall the hole was about 1/16” diameter or smaller.
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #17 ·
I think I have the venting deal figured out now, I’ll crank “Ooo that smell by Lynard Skynard at the stoplight and my neighbor in the other lane can just enjoy it...
What do you people use to remove all the greasy nasty off of the engine and lower and rearward residing components???
 

·
More for Less Racer
Joined
·
20,117 Posts
I What do you people use to remove all the greasy nasty off of the engine and lower and rearward residing components???
If the engine is out on a hoist or stand, and you plan to repaint all the components, then good old spray Easy-Off kitchen Oven cleaner will cut through most anything but will remove paint as well.
Then power wash off or paper towel wipe and then final clean with spray Brake cleaner.
Slower but will get you there....several cans/case of brake cleaner, and some stiff bristle brushes, scrapers, putty knife and work away at it.

Definately carefully save all that A.I. R. stuff, a restorer may give you pretty good money for all of it.....it was commonly the first thing thrown away back in the day which makes them rarer today.
 

·
Registered
Joined
·
3,847 Posts
find somebody that does auto detailing with a real steam cleaner---my dad restored cars and the steam cleaning was the first thing done---steam at high pressure will remove most everything but metal
 

·
Registered
Joined
·
425 Posts
Lysol full strength, scrub brush and power washer. I work in the solvent with a 4” paint brush. Something smaller for the transmission crevasses. Final clean with brake cleaner.

in fact I do regular cleaning every year on the whole chassis/engine with Lysol in spray bottle 1 1/2” small paint brush, and rags.
 
1 - 20 of 23 Posts
Top