Been wondering for a while about an issue that engines from our vintage vehicles tend to have... blow-by gasses coming out the breather cap and draft tube, generally looking gross and polluting the air at every stoplight and sign. Made it so I didn't even want to look at pretty girls as I pulled up alongside, in case they noticed the fumes making my van look like something out of a Cheech and Chong movie!

With the help of the users on the FordSix forum, I also learned that the accumulation of these fumes in the engine contribute to the build-up of sludge. The introduction of the PCV system to the engine allows these blow-by gasses to be reintroduced to the intake charge, and effectively evacuate the fumes from the crankcase. The intent is that the engine stays cleaner and the engine more completely burns it's fuel. The use of manifold vacuum is much more effective at getting rid of the fumes (that otherwise escape the engine) than the atmospheric vacuum created when air passes by the end of the draft tube while in motion. With their advice, I was successful in performing this conversion and virtually eliminating the need for me to hide my face when I stop at a light!

This conversion was on the van's 65 Ford 240 Big Six. I plan to upgrade my 62 Ford 170 Small Six in the same manner. Only difference is the draft tube location... front of block rather than back of valve cover... there is a way though!!! Hope this helps any of you that may be curious about this.



Removing the draft tube:



Removing draft tube hose bung, installing PCV valve and grommet.







PCV gasses enter the intake charge below the carburetor so gases do not gum up the carb. Removing manifold "plug" (coolant temp sensor?!?!?) and adding a bung. I've since wrapped these threads in teflon tape... just brass elbows the parts guy helped me size up.







Complete PCV system (includes original breather cap).



That's what I've been up to this week, in an effort to get my vehicle driveable again. I did notice initially that my carb neeeded tuning badly. The mixture screw was turned way out, which contributed to more visible fumes. If you perform this upgrade, expect that you will have to doublecheck your carb settings, though they should not change dramatically... the net result of the PCV system to the intake charge is like introducing a controlled vacuum leak.

On my conversion, I completed the job about 1am, as I was rushing to have my van available to some activity the next day. In my overtired stupor though, I reconnected the throttle cable wrong and it was binding. The next morning, after reattaching the throttle cable, the van is good to go!!!

Seems to me that would be a big old vacuum leak if you have an oil cap that is also a breather. If you could seal up the system I bet that really does reduce smoke, well done!

My guess would be that when the PCV signal is strong enough to open and draw fumes from the crank case, it would then breathe through the cap... it really isn't any different than a new vehicle that has the large hose running from the valve cover to the filter mounted on the inside wall of the air cleaner... I did read that it is in fact a "vacuum leak", but it's "controlled". To compensate, I think you would open your idle mixture screw just a little to accommodate the air and fumes coming from the PCV.

The difference is night and day with my engine. I recently got compression readings... two cylinders around 80 psi, two around 115 psi, two around 130 psi... tons of sludge was built up and blow-by was obvious. Now when idling at a light, there are no fumes at all. I assume that sludge is no longer accumulating either.

Back when I got the van, I dug into the engine to deal with lifter noise, and de-sludged all I could see. I'm no longer worried about the chunks of sludge. And I've since swapped on another oil pump in case it was the cause of my poor top-end oiling. Have done the Rislone treatments and engine flushes... that part's all good for now. But I definitely have to make rebuilding my other 240 a priority! Actually think I'll be getting the short block started in earnest next week... that's another topic.

Bottom line is that my current engine was filthy using the draft-tube configuration, and I am convinced that the PCV system would have done a world of good on this engine. My results today are night and day.

Wow, this is a great mod. I definitely plan on doing this to my van. A few questions.. (I know this is an old thread, sorry!) Do you remember what the pcv valve you used was out of? Also, I am a bit confused, did you keep the original breather cap, or replace it with a sealed one? Thanks!

Thanks for the info Rod! This will be a very big help.. One more question.. Do you guys keep the oil bath? I was thinking I could fit a round paper filter in there and get rid of the oil. Any suggestions as to which is better or if it will even work?

the only concern i would see with coreys set up is if the valve cover did not have a baffle where the pcv now lives, if the top end oiling is real strong oil could be pulled up through the pcv, i doubt it would happen but i guess it could.
ford also had a valve cover breather with the pcv in it, i think it was on some 300's but im not sure.

Wow... I haven't been around for a long time... wasn't feeling well and weather has sucked for the last year! Yes, valve cover has a baffle. Still use a breather cap, which I think is no problem because of the baffle... I like the look of them too. Still have the oil bath air cleaner. PCV routed to the intake manifold.

Parked the van not long after as snow flew! C'mon , SPRING!

Nice to see you back sasktrini

SoapDude wrote:Thanks for the info Rod! This will be a very big help.. One more question.. Do you guys keep the oil bath? I was thinking I could fit a round paper filter in there and get rid of the oil. Any suggestions as to which is better or if it will even work?

Hey Dude, I have an oil bath air cleaner assembly with a paper filter inside of it! I gutted all of the oil bath innards and installed a Wix #42055 paper filter. Simple to do, just takes a little time.