Hey guys I just got my roller 351 in my 86 f150 and was wanting to do some cleaning up under the hood. I was wondering if it would hurt to delete the pcv valve and lines and just use some of those push in breathers in the valve covers. Had a fella tell me once that without the pcv it will blow the seals in the engine but if both valve covers have breathers I don't see how it could blow seals. I always thought the pcv was more of an emissions thing isn't it? I remember the old chevy 283 and 327 never ran a pcv but just had breathers in the valve covers or one in the front of the intake. What do you guys think?

 

Keep your PCV. It helps evacuate water vapor as well as blow by. This will help reduce any sludge build up in the engine.

 

I didn't think of that. I will probably just keep it then. So is there any truth to the blowing seals thing or is that just BS?

 

crankcase pressure can cause seal blow out under high RPM as well as cause oil to be pushed out around the seals.


You could remove the PCV valve, all it does is help reduce crank case pressure as well as evacuate blow by gasses.


As far as removal of water vapor, that's a new one for me. If there is any moisture in the crankcase it will boil and the PCV would remove this from the crank case.


Now as far as the seals blowing out goes, honestly you would see that with a engine that has serious blow by. A good engine with moderate blow by probably wouldn't blow the seals. Look at the old engines before the PCV came out in the late 50`s. They had a road draft tube that really didn't help pull anything out of the crankcase until you were moving along at about 40+ mph. They didn't have a problem with blowing out seals but then again they also used a rope seal which had their own problems.


In the end if you want to dress up your engine bay they do sell polished and billet PCVs that you could install, a '69 Camaro we installed a race engine in it has a bullet style billet PCV valve with black nylon braded hose connecting it to the carb.

 

I have a 1965 G.M.C. 1 ton, 1966 Pontiac, 1967 G.M.C. 1/2 ton and another motor on a stand , all 283's. The pcv valve screws into the back of the carb and goes to a hose adapter at the back of the block, by the oil sending switch. The oil filler spout has a breather, pushed on at the front of the intake. The valve covers are closed ( no holes). I know the 283 came out in 1957 to 1967. I don't know if the 283's earlier then 1965 came without a pcv valve.


My 327 came out of a 1968 Impala, it's pcv valve goes from the back of the carb to a valve cover hole on one side, and the other valve cover hole goes to the air cleaner. The oil filler spout is a twist on cap.


I would definitely run with a pcv valve.

 

Keep the PCV, "clean it up" by making the PCV symmetrical and well done with molded hose elbows connecting stainless steel tubing.

 

the PCV dates back to 1957 on the 283, my '63 283 has a PCV valve that screws into the intake manifold. Then it hooks to a pipe that plugs into the back side of the block which sucks the air through a can baffle located on the driver side rear of the lifter valley.


The 283 block was never changed from 1957 and you can install a 1967 283 - 327 even a 350 small block in a 57 as they all have the mounting points for the front mount engine mounts used in '57.


The PCV came out in the late 50s and Chevrolet copied as well. Ford came out with them around '57/'58 but it was a California option. Chevrolet how ever had them installed in all vehicles though considering how it pulls the air through the block.


Heres a picture of mine, lower right you can see the OEM style PCV valve that is installed in my aftermarket manifold and the black grommet to the left of the dist opening is where a metal pipe plugs into and curves around to the PCV with a small piece of rubber connecting the two.





This one you can see the can baffle that Chevrolet used to prevent the PCV from sucking oil from the lifter valley.

 

Wow! that's neat, never seen a pcv in the block on a sbc engine. Never knew they did that.

 

Thanks for the pictures, I was trying to picture it in my head. Is the rubber grommet from the factory. That's where my hose adapter goes, then to the pcv valve (just like yours, but to the back of the carb). Check out www.mortec.com, there are approximately 20 different 283 block casting numbers. I'm not sure what the differences are, but there must be something.


You are right about interchangeability with small block chevy's, apparently putting 305 heads on 283's is amazing results. I have the same heads as you, and I'm quite happy with them.

 

I have been thinking of pulling that engine apart again and going through it. There were some things I was not happy with during assembly and I just let it ride to see how it runs.


But as far as I know the grommet was always there. All that was done was I reused what was there and modified it to work with the aftermarket intake.

 

x2.

PCV do systems help emissions, but their original purpose was to clear the crankcase & oil of moisture, fuel, acids etc.
GM began using them on GMC engines during WW2; but stayed with draft tubes on civilian vehicles for a long time.

http://www.curbsideclassic.com/wp-co...19-085-950.jpg

 

I was going to mention my dad's '52ish GMC M135s had PCV valves. I was always under the impression that they did this to keep the engine sealed up for fording streams. They had a snorkel set up that had an air intake in the cab. With an extension tube, you could drive it submerged. Hard to fit behind the wheel in scuba gear....

A bit off topic......

NOTES

 

Yes the grommet is from the factory, I have a shop manual for my 1965 G.M. truck, which starts at 1963. I looked up pcv ,and it shows the picture with that same rubber grommet and metal elbow, and it pipes into the back of the carb. Thanks again for your pictures.