Converting Road Draft Tube to PCV on a 170

[Anonymous]

Hi all.

I've got a 62 Comet S22 with a 170 in it. I've replaced the trans with a rebuilt C4, upgraded the radiator to a 3 row core, put in a dual master cylinder, installed a dual exhaust header, and replaced all the ingition parts. I won't be able to have the engine rebuilt for a while and the blow by is terrible -- especially at stop lights. I'd like to ditch the road draft tube for a PCV to address this problem.

Has anyone done this on a 170? I'm guessing I remove the tube, put some kind of gromet in the hole, attach the PCV to that, and then run some hose into a vacuum sorce on the carb. But does anyone know or have a part number for which PCV and gromet will work?

Any help is much appreciated!

Thanks.

Adam

 

[BIGREDRASA]

Does the tube go into the valve cover? If so, get a grommet and a Pcve valve for a 200. The only this is you need to hook it into vacuum at the base of the carb. A large vacuum port. Do you have one of those?

 

[jamyers]

Hmmm. On my '62 170, there was a metal fitting that went into the hole, and a hose went to a PCV valve that threaded into the carb adapter plate. Here's a pic of the old engine with that fitting - Junkyard is only place I know of to get one.

I've heard of people plugging the hole with a freeze-plug, and swapping to a later valvecover with the hole...but I don't know of anybody putting a grommet in the draft-tube hole, that'd be a decent idea.

And I'd be sure to get a '62 PCV valve from the parts store, the wrong one can screw up your carb settings. Ask for one for a '62 Ranchero 170.

 

[BIGREDRASA]

The hole in the block is covered with a fuel pump block-off plate. That's the easy part. Connecting to the manifold is the tough part. James, do you have pics of the other side?

The hard line out of the manifold is for the tranny. The rubber hose at the base of the carb is for the PCV.

 

[BIGREDRASA]

On the issue of PCV valves, James posted elsewhere:

Today I got the right PCV valve for my engine to replace the one with a 90-degree elbow on it that I had on there, and it actually changed the AFR's to for the richer - apparently the one I had let too much air in (whodathunkit?

If you run an elbow, make sure you stick it onto the correct valve. Pics from the Motorbooks Restoration Manual. (I'll bet they got them from Ford.)

 

[jamyers]

The hole in the block is covered with a fuel pump block-off plate. That's the easy part. Connecting to the manifold is the tough part. James, do you have pics of the other side?
...

No, and I wish I'd taken more "before" pics.
Mine originally was like in your pic, the PCV was a small-diameter one that threaded directly into the carb adapter, and something like a 1/2" or 5/8" hose went from it over to the 90-degree block fitting.

 

[Anonymous]

Right now the set up is what I believe to be stock: there is a hole on the driver's side of the block which the tube is attached to, and the tube just points down, allowing the crank case to ventilate -- or really billow -- into the atmosphere. There is also a fitting on the valve cover with a tube that connects to the air cleaner. My understanding is that the road draft tube will vent at idle, and the valve cover tube will vent when the throttle is engaged.

What I want to do is convert it to a closed PCV system, where I replace the road draft tube with a PCV, and run some line from there into a vacuum port at the base of the carb. I will keep the valve cover fitting plumbed into the air cleaner. That way all the crud from the crank case gets burned -- or at least it goes out the tail pipe instead of into my face when I'm at a stop light with the window down!

I've seen articles on how to do this on a Y-block (with Napa part numbers and everything) and someone sells a kit to do it for Chevy 6s. But I haven't seen anything for Ford 6s. And I'd rather not do the trial and error thing and make 10 trips to the parts store if I can help it!

 

[Bort62]

You've got the right idea, but I think you are going to have to be a little creative on what parts to make it work.

The line running into the air cleaner is actually an inlet. the idea w/ a road draft tube is that the air flowing past the end of the tube while the car is traveling down the road creates a slightly lower pressure zone (venturi effect) and pulls gasses out of the crank case. In an engine with good rings, you won't actually have much blowby gas so you need some sort of inlet to supply fresh air to the crank case. That's the reason for the line to your airfilter. The reason it is behind the airfilter is so that it is filtered air.

Doesn't work very well in practice. replace the RDT w/ a PCV valve, and leave the rest alone. Run the PCV valve to manifold vacuum.

 

[BIGREDRASA]

One probelm you'll run into very quickly is aplugged up PCV. The smoke congeals into gummy oil deposits on the PCV valve plunger. At that point the PCV valve gets plugged, and you'll start bathing your air cleaner and/or carb with oil.

It might be more practical to cobble up a road draft tube extension so it vents on the passenger side.

 

[jamyers]

Yup, the hardware on the valvecover/aircleaner are to filter the air going into the crankcase. Like Bort said, just need to figure out some way to connect to the RDT's old hole in the block, and then to the intake manifold with a pcv somewhere in between. Seriously, if there's a junkyard with old cars nearby, I'd go looking for the Ford part.

OR, you could block off the RDT hole completely, and I think they make oil-fill-caps that seal to the valvecover and have a tube for a pcv hose.

(Road-Draft tubes only work while you're moving, unless you're sitting still with a 30mph+ headwind.)

 

[jamyers]

One probelm you'll run into very quickly is aplugged up PCV. The smoke congeals into gummy oil deposits on the PCV valve plunger. At that point the PCV valve gets plugged, and you'll start bathing your air cleaner and/or carb with oil.

It might be more practical to cobble up a road draft tube extension so it vents on the passenger side.

Well yeah, but with weekly cleanings you can go a looooooooonnnnnnng time. (don't ask how I know that)

 

['61 Draggin Wagon]

Like was said before, get a pcv elbow from the block of a '62 Falcon. Then get some pcv hose(not heater hose) & the pcv valve that threads into the carb spacer. I have one of those elbows somewhere. But haven't seen it in about 10 years. It was a junkyard find......
On my '61 Falcon, when I first got it(about 33 years ago), it had the road draft tube. Back then, My dad bought a kit from AC that had the breather hose, fill cap with a hose nipple & the fittings to attach to the aircleaner. It also had all of the parts & directions to install a pcv valve, by turning the road draft tube upside down, sawing it off about 5 inches from where it mounts to the block & installing an expanding rubber fitting into the RDT. Then a brass fitting screws onto the exposed threads from the rubber fitting & the pcv hose attaches to that & then the pcv valve screws into the carb spacer. No, I don't have the part number. But its the only one I've ever seen & it works fairly well.
Darryl

 

[jamyers]

...turning the road draft tube upside down, sawing it off about 5 inches from where it mounts to the block
...

Awesome idea! Clamp some hose onto the tube, get a hose reducer, and you're on your way.

 

[LaGrasta]

there are other post on this from awhile ago. I did mine in reverse flow because it made more sense and has been successful for years now.
I have a crankcase filter attached to the original road draft tube connection in the block. Then I added a PCV in the valve cover and ran that to the intake manifold. Hot air rises so now it sucks the air at the highest point in the engine and draws in cool air in the block.

 

[69.5Mav]

greaser56

I have a 69.5 and a 72 MAV both are 170's, both have PCV's. All you need is to block off the road tube and get the carb spacer and valve cover from any early 170 MAV's and put them on. Then rout the PCV from the valve cover to the carb spacer and supply filtered air to the other side of the valve cover and you are done. I use a big fuel filter to supply filtered air to the inlet side of the valve cover. Find a 70's vintage MAV in a junk yard with a 170 and take what you need.

Good Luck

 

[BIGREDRASA]

Hot air rises so now it sucks the air at the highest point in the engine and draws in cool air in the block.

Problem comes with blowby, which is the presenting problem. The crankcase is pressurized by the gases blowing past the pistons.

Adam, I can send you my old valve cover, then you just buy the grommet & PCV valve. However, on the '66, the PCV valve goes into the the rear of the valve cover, and the front is the breather, which can go to the air cleaner or not. Check out the pics in my earlier post. That is not a PCV into the manifold. The PCV Valve is a common one for Fords.

Check out: http://www.power-21.com/honeywellpower2 ... x?b=F&vt=1

Although the PCV valve is a simple device, it is designed to reduce the air pressure inside the engine and redirect it to the air intake system. Since the air is contaminated with oil, gasoline and engine metal residue, this in time will affect the operation of the valve assembly. The valve can plug up over time, which will result in a poor running engine that delivers less power and reduced fuel economy. It is good maintenance to check and even replace the PCV valve in your vehicle every 30,000 miles (50,000 kms). It is a simple and inexpensive repair that will help contribute to a fuel-efficient and smooth running engine.

 

[jamyers]

Problem comes with blowby, which is the presenting problem. The crankcase is pressurized by the gases blowing past the pistons.

No problem, the crankcase and valvecover are interconnected via the pushrod passages. Pull from one or the other, same/same.

 

[LaGrasta]

Problem comes with blowby, which is the presenting problem. The crankcase is pressurized by the gases blowing past the pistons.

No problem, the crankcase and valvecover are interconnected via the pushrod passages. Pull from one or the other, same/same.

My thoughts exactly.