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Does anyone know if the part labeled as 'connector" 3723626 is a metered orifice or if its just a straight thru connector. Can't find anything in searches.
my .02... 5645907 is a PCV, there is no reason for 3723626 to be an orifice UNLESS the vacuum needs to be maximized for the advance and the washer; if so, then the PCV is simply a check valve
The part ID'd as a connector is just a hose nipple of sorts.
It's the "of sorts" I'm wondering about. My 65 FI has a fitting with a metering orifice and No PCV. So never really sure what to expect on these early PCV systems.
It's the "of sorts" I'm wondering about. My 65 FI has a fitting with a metering orifice and No PCV. So never really sure what to expect on these early PCV systems.
The '65's used the fixed orfice across the board.
The early engines used the variable orifice controlled by a pintle. There's no reason an engine would need both a valve and then upstream restrictor.
So heres current thinking. This is a 1970 LT-! motor that is going into my 1961 touring car. i'm keeping everything pretty much stock including the Fuel Injection unit. the block has no vent so I welded in a baffled fitting at the back of the valve cover. my plan is to tie the PCV valve shown to the injection unit as the factory did. i plan to use a vented oil filler cap so that air will be drawn in at the oil filler , exit through the valve cover, thru the PCV valve and then into the Fuel Injection plenum. What do you experts think of this setup?
As an option could I rout the gray hose shown( not connected yet) to the air cleaner instead of the FI plenum. would that work as well. It's not what the factory did but in 65 on FI cars they just used a metered orifice and routed the vent tube/backfire suppressor into the air cleaner.
So heres current thinking. This is a 1970 LT-! motor that is going into my 1961 touring car. i'm keeping everything pretty much stock including the Fuel Injection unit. the block has no vent so I welded in a baffled fitting at the back of the valve cover. my plan is to tie the PCV valve shown to the injection unit as the factory did. i plan to use a vented oil filler cap so that air will be drawn in at the oil filler , exit through the valve cover, thru the PCV valve and then into the Fuel Injection plenum. What do you experts think of this setup?
As an option could I rout the gray hose shown( not connected yet) to the air cleaner instead of the FI plenum. would that work as well. It's not what the factory did but in 65 on FI cars they just used a metered orifice and routed the vent tube/backfire suppressor into the air cleaner.
Jerry,
I think crankcase vacuum at idle and low speed will become pressure at higher engine output that will be forced back out through the vented oil filler cap. The small diameter PCV valve may not be large enough to handle the volume of air from the crankcase.
Think about how a 63 system functions. It too has a PCV valve but it also has a 1/2" diameter vent tube from the oil filler tube to the air cleaner.
For 64, engineering learned that even at 1/2", the tube wasn't large enough so the system was increased to. what, 1 1/4", or more?
I am thinking the same thing. That is the reason I purchased a pre 1968 327 block for the 383 stroker I am having built for my 57.
Possibly a 2nd PVC hole in the other valve cover and going to the air cleaner base with the tube rather than the fuel injection unit?
I used LT1 valve covers with a push-in filler/breather cap in one side and the pcv in the other AND plugged the original filler hole in the adapter manifold. in my opinion, pulling side-to-side thru the valve covers is better than just through one.
I am thinking the same thing. That is the reason I purchased a pre 1968 327 block for the 383 stroker I am having built for my 57.
Possibly a 2nd PVC hole in the other valve cover and going to the air cleaner base with the tube rather than the fuel injection unit?
I was using the setup the factory used for 61/62 Corvettes shown in my original entry , however I like the idea of going into the air cleaner rather than the Fuel injection plenum but that reduces vacuum. I don't really understand why factory went back and forth on this. Does someone on the forum have a better understanding of the engineering here?
So heres current thinking. This is a 1970 LT-! motor that is going into my 1961 touring car. i'm keeping everything pretty much stock including the Fuel Injection unit. the block has no vent so I welded in a baffled fitting at the back of the valve cover. my plan is to tie the PCV valve shown to the injection unit as the factory did. i plan to use a vented oil filler cap so that air will be drawn in at the oil filler , exit through the valve cover, thru the PCV valve and then into the Fuel Injection plenum. What do you experts think of this setup?
As an option could I rout the gray hose shown( not connected yet) to the air cleaner instead of the FI plenum. would that work as well. It's not what the factory did but in 65 on FI cars they just used a metered orifice and routed the vent tube/backfire suppressor into the air cleaner.
I think you'll be fine with this set-up. It is similar to many, many, factory installs over the years. I'm running a '67 383 stroker in my '61, and have the PCV plugged into the road draft hole with a grommet and going directly to the rear of the rear carburetor. Works just fine. I used a generic GM PCV Valve from a Pontiac 400.
I was using the setup the factory used for 61/62 Corvettes shown in my original entry , however I like the idea of going into the air cleaner rather than the Fuel injection plenum but that reduces vacuum. I don't really understand why factory went back and forth on this. Does someone on the forum have a better understanding of the engineering here?
You need manifold vacuum to make the PCV valve (or the fixed orfice) work correctly.
The only real flip flop was the source of clean air. The early models pulled in fresh air through the oil fill cap. The only air filtering you have there is whatever the oiled mesh will catch. Pulling the fresh air through the air cleaner gives much cleaner air and less dirt going into the crankcase.
Pulling crancase vapors out with manifold vacuum and letting fresh air in through the air cleaner has another benefit. It keeps a constant vacuum on the crankcase which will stop oil vapor discharge on the engine, decrease oil leaks. It will do this as long as blowby doesn't exceed the capacity of the PVC system.
You can read about it here. The closed systems became mostly universal in 1963, not 1968 as listed in the article.
One other item I can think of is the fact that with the original system, the crankcase is vented through the baffle, or oil separater that's mounted in the valley that separates oil from air/fumes. I don't know if this would be an issue.
Also, the original system worked well at low engine RPM/output but as crankcase pressure increased, it became high enough to force the PCV system to work backwards. The PCV system couldn't keep up with the volume of air pressure and oil/fumes exited through the oil filler cap. Very common issue for those cars. The fix for racers at that time was to tie a shop rag around the oil filler tube just below the cap.
I have a 1970 LT-1 short block in my 61.. but it's not FI.
I use an open oil filler. I drilled a hole in the rear of the intake. I fabricated an "oil separator" (length of copper tubing with small holes drilled into it). Hose to in-line PCV, to full-vacuum on the Carter WCFB.
The system works well. No oil or vapor ever comes out the filler. The oil stays clean for extended time. I have minor oil consumption (1/2 Q every 3000 miles), which I am convinced is happening at MAX vacuum (deceleration with throttle closed).. Likely my 'simple' oil separator is allowing some oil through.
I was using the setup the factory used for 61/62 Corvettes shown in my original entry , however I like the idea of going into the air cleaner rather than the Fuel injection plenum but that reduces vacuum. I don't really understand why factory went back and forth on this. Does someone on the forum have a better understanding of the engineering here?
For a pvc to work you need manifold vacuum, you have air flow in the air filter but very little vacuum. The system you show would be fine getting its vacuum from the plenum., however if you replaced the vented cap with a sealed cap and put a hose from the filler to the air filter for the systems free air that would work too.
You need manifold vacuum to make the PCV valve (or the fixed orfice) work correctly.
The only real flip flop was the source of clean air. The early models pulled in fresh air through the oil fill cap. The only air filtering you have there is whatever the oiled mesh will catch. Pulling the fresh air through the air cleaner gives much cleaner air and less dirt going into the crankcase.
Pulling crancase vapors out with manifold vacuum and letting fresh air in through the air cleaner has another benefit. It keeps a constant vacuum on the crankcase which will stop oil vapor discharge on the engine, decrease oil leaks. It will do this as long as blowby doesn't exceed the capacity of the PVC system.
You can read about it here. The closed systems became mostly universal in 1963, not 1968 as listed in the article.
I think you'll be fine with this set-up. It is similar to many, many, factory installs over the years. I'm running a '67 383 stroker in my '61, and have the PCV plugged into the road draft hole with a grommet and going directly to the rear of the rear carburetor. Works just fine. I used a generic GM PCV Valve from a Pontiac 400.
04-18-2017, 06:12 PM
C1 pvc
