On the side of my y block there is a draft tube. Can thi be deleted? I have read a few posts saying I can. The posts say put in a POV valve routed to air cleaner or manifold. I also have oil filler with a breather. So if I have a breather on my oil fill tube do I need a PCs valve system? And how can I block off draft tube hole?
thanks
jerry

 

You can block it off, but you will need the PCV valve. I use a filler breather to the air cleaner and a PCV fitted to a valve cover. I'm running an Edelbrock carb which has the PCV port at the back. Later style valley covers have provision for a PCV valve at the back which would be the better way to go if you can find one. I had to experiment with several PCV' valves until I found one that had the correct flow. They are basically a controlled vacuum leak at idle,so it can't flow too much, but if you go too small, the flow is inadequate to purge the crankcase fumes. I can't advise you on how to block off the road draft tube. Haven't seen how they are arranged.

 

Yes, one quick way is cut a gasket with no hole and bolt the draft filter/tube back or cut a tin plate with gasket. PCV valve (a good thing) The draft tube only works when the
vehicle is moving and does nothing when stopped, PCV works all the time. Do some
research maybe Napa. This system came out in 1964 on small Y blocks because my
64 F350 with a 292 has it and also there is no hole in the block for draft tube/filter...What I would do is a closed system get a rubber plug for the oil fill pipe, drill a hole in driver side valve cover and rubber hose from valve cover to air cleaner. The PVC is located passenger side to engine vacuum. Also all engines went to PCV
on about 1964, exception I had a 1961 Lincoln 430 cid and that had one.. Maybe
check venders specializing in late Y Bocks its really a no brainer to do this...

 

Just drilling a hole in a valve cover, even for a breather cap is not the best method. There should be a oil baffle inside the valve cover under that hole. The baffle will stop oil from spraying up into the breather. If a hole in the valve cover is the only option, Moroso makes some rubber grommets that are also a baffle.

 

Yeah- I forgot to mention that I had to weld in a bit of metal under the valve cover to shroud where the valve pokes in. Otherwise you'll suck oil. Best would be to find the later style valley cover that has the provision for the PCV.

 

I learned this the hard way many, many years ago when I was a teenager. After drilling my chrome valve covers it was pointed out to me what was going to happen without baffles inside of them.

 

ok I understand making a gasket to block off hole. But a couple of questions popped up. If I have a breather on oil fill tube. Do I need a pvc valve.? And if I kept the draft tube can I just run a hose from draft tube to air cleaner? Just things rattling in my brain.
thanks
jerry

 

You could run with just the breather, and no draft tube or PCV. You will have a fog out of that breather many times, and your oil will end up with water in it from time to time.

If you run a hose from the draft tube to the air cleaner, you will probably make a pretty good mess inside the air cleaner, your carb, intake etc, and foul some plugs. There wouldn't be much control in that circumstance, although it would be better than just capping it off and using the breather only.

The idea of the PCV system is to pull blow-by, water vapor, fuel vapor etc out of the crankcase, and draw in clean air. The fumes go through the motor and are burned up, evaporated, and in later stuff ultimately dealt with by the cat if they get by the combustion process.

Diagram here will help to visualize the setup:

https://www.aa1car.com/library/pcv.htm

 

Short answer, no. Apparently you still don't have a clear understanding on how crankcase ventilation works, so I'll try to help with that. Air has to go in, and air has to come out. Typically, fresh air goes into the crankcase through the oil filler cap, either through the use of a vented cap, or in a closed system you'll have a hose connecting from the oil cap to the air cleaner, so any backflowing fumes will go back into the carburetor instead of the atmosphere.

Originally, air would exit the crankcase through the road draft tube when the vehicle is driven. Air passing under the open end of the tube draws a vacuum and pulls dirty air out the tube, and into the atmosphere. That was found to be the cause of a lot of air pollution, and a more self contained system was designed where the engine itself would draw the crankcase air back into the engine to be burned and exited through the exhaust. The control valve that regulates the amount of dirty air going through the engine is the PCV (Positive Crankcase Venitlation) valve.

This is a basic, 'in a nutshell' explanation, but as you can see, the bottom line is you need an air in and an air out situation for the engine to operate properly. Without proper crankcase ventilation, pressures inside the engine will blow out gaskets and oil from "somewhere". I hope this helps.

 

Thanks52 merc. I didn’t understand the process of PCv or draft tube. So air goes in thru vented oil filler cap and vented to atmosphere from draft tube. I hope that’s correct. So if I delete the draft tube I can have a pcv valve on valve cover. And then I can vent it into the intake manifold? If I put a pcv valve in valve cover any suggestions where to mount pcv valve ?
thanks
jerry

 

The most common place in valve covers on Ford V8 motors is towards the rear of the right side (passenger side) valve cover. Like was mentioned earlier, when installing a PCV valve or breather (especially a PCV valve) in a valve cover, an oil baffle must be installed on the inside of the valve cover below the PCV valve hole. If not, oil spray from the valve train will get sucked into the PCV valve and into the motor ending up with blue exhaust smoke and in severe cases, oil fouled spark plugs. If installing a baffle inside the valve cover is not feasible, a grommet with internal baffle like this should be installed. https://www.summitracing.com/parts/mor-68772



Ultimately, a PCV system is better for the motor than the road draft tube. With a PCV system, you'll have no or very little condensation build up inside the motor, reduced oil leaks because of less crankcase pressure, motor oil will stay cleaner longer, and no oil vapor buildup under the truck.

 

What carb are you running? If it's the old Ford/Holley two barrel with no PCV vacuum port provision, you are better off finding or making a spacer with a port under the carb as the vacuum source than using some available port in the intake manifold. The blow-by gasses that get sucked into the intake stream are better distributed and burned if they go in just under the carb vs into the back of the manifold someplace where said gasses may only get ingested by a couple of cylinders. This can cause rough idle.
The popular newer carbs are equipped with a vacuum port already.

 

I have a Holley 650 carb. It has a vacuum fitting on the rear of the carb. So I can drill a hole in the valve cover. I just have to be sure there is a baffle so direct oil doesn’t come thru the the pvc valve. Then connect this to the base of the carb?
thanks
jerry

 

That sounds correct to me. Make certain whatever is used for a baffle doesn't interfere with the rocker arms. Lastly, leave the breather cap on the oil fill tube. Fairly simple but much better setup.

 

Ok I think this is right. You need to vent the crankcase and vent it to manifold to be reborn Ed. My draft tube has a fitting on the side of it. Can I run a hose from the draft tube to the bottom base of my carburetor? The oil fill neck has a vent. That way the block gets vented and the unburdened gas goes to the carb.
thanks
jerry