Hello All.

65 352 FE, having some issues with the PCV or.....Cobbled up system my motor has on it.

What was existing, was a breather on both valve covers when i got the truck.
The engine has an Older 352 INTAKE with the oil fill on the front ( This has an open ended breather cap on it ). it ALSO has a road draft tube on the back, which is very much loose in the back of the intake.

Its worth mentioning that this manifold is being replaced with an edelbrock performer i picked up.

Here is the issue:

I installed a new breather on the driver side VC. I then installed a PCV breather cap on the passenger side, which is connected to my carburator vacuum port at the base. All seemed OK for a bit. Then, i noticed the truck was getting louder, running terrible. In digging around, i pulled the line off that PCV and plugged it with my finger. the manifold exhaust leak quieted down. Idle dropped nicely to about 600 and motor smoothed out. Last night i replaced that PCV breather figuring it was bad, and now the motor with the new PCV runs like it did when i plugged it with my finger. Only issue is. Upon doing this my oil pressure dropped from around 55 to about 30. The old PCV i noticed alot of oil in it.

Is my issue the two " systems " original / new combating each other in some way and not allowing the case to breathe properly? Im trying to figure this out, so i know what the proper steps to take are when i install the new intake manifold.

 

Sounds like you had a bad pcv valve and replacing it fixed the problem.
The lower oil pressure is most likely because of the slower idle, reset the idle to around 800 rpm.

 

Thank-you!! So you dont think i could be having an issue like i've read on here many times now.............with the exhaust crossover in the intake over-pressurizing the intake due to bad seal?

 

1958/64 FE engines were only installed in cars. Have rounded valve covers without holes in them for smog valve/oil cap, have an engine oil fill tube at the right front.

1961/64: Smog valve (PCV introduced in 1961) threads into a boss of the intake manifold, in front of the carb.
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1965/76 FE engines (1965/71 cars; 1965/76 F100/350) have pent roof shaped valve covers.

Smog valve fits into a rubber grommet at the rear of the right valve cover. Oil cap located at the front of the left valve cover.

1965/67's use a different grommet (it's not reproduced, but it's available NOS) for the smog valve than 1968/76.

1965/67's use a different oil cap with PCV than 1968/76.

 

Thankyou!! - While my engine is a 65 block, according to the engine tag, others here have identified my intake as being from an old version of the 352 in a car. Why the intake was swapped i dont know, but along with the intake came the oil fill tube / road draft tube out back.

 

1965/66 FE engines without PCV: The road draft tube fits into a grommet at the rear of the right valve cover (where the smog valve would be located with PCV).

 

Actually I've never heard about that happening, but if it did you'd have more blow by out the road draft tube or the oil fill cap.
PCV valve is designed for a controlled vacuum leak, it only allows so much blow by into the intake no matter how much the engine produces.
The fact that you regained idle control and a smoother running engine tells me the old pcv was bad.

FE engines are well known to drop 20+ psi oil pressure at low idle, I've seen several run 60 psi driving and 20 psi idle, but your engine should be set at 750-800 rpm for manual trans, 900 rpm for auto trans, 600 rpm is to low.

 

600 rpm with an auto is ideal when in gear at a stop.

 

Yes, In gear
Torque convertor will pull the rpm's down 2-300, in park they should be set around 850-900.