OK...here we go...I have been all over this site and the Ford Barn trying to figure this out. Here is what I've got 1937 21 stud engine (early model) internal vented Offenhauser 2 x 2 intake. (late model) external vented The early model engine has an internal draft tube that vents OUT the pan vent. The late model intake has an outlet for an external vent tube. I plan on installing a PCV where the external vent tube is supposed to go on the manifold (driver side front) and pipe it to a vacuum source at base of rear carb (existing 1/4" tapped outlet). Now remember....early model engine-late model manifold. Here is my question...Do I need to plug my internal draft tube (right under the intake manifold in the valve galley) or leave it as is and just add the PCV set-up in the manifold where the draft tube is supposed to go. I don't want to get rid of this manifold as I have mega bucks tied up in it and polishing. I can if needed machine a plug for the intake DT port, but would really like to use a PCV set up and this port is the most logical place. Having trouble visualizing all this. Thanks Crosseyed Ron
You do realize that the PCV will pull air in around the rear main bearing (and any other opening) into the crankcase.
^ that is not quite true. You need air in and out. But if you run the original oil filler on the fuel pump stand you should be fine. I would cap the road draft tube at the bottom or better yet run it back into the pan. Make sure the PCV valve sits vertical. It may not work correctly at the manifold angle. Dodge flattys in military vehicles run a steel rebuildable "Donaldson" valve. They attach with pipe threads and look nice and era correct, probably because they are.
I intend to make a blockoff plate for the fuel pump boss with a KN filter mounted on top then use a filler tube with a non vented cap up at the filler tube inlet next to the draft tube outlet. This way the fresh air flows the length of the engine.
http://www.jalopyjournal.com/forum/threads/59a-crankcase-ventilation.864615/page-2 I was wondering if you saw this thread. My manifold is different of course but you can see what I did at post 40 of this thread. The system seems to be working well. There is more detail on the system in my build thread .
Here is how I ran my PCV valve...have no idea if it will work correctly or not, but as soon as I do my motor swap I will report on how it works. If anyone sees an issue let me know, great thing is, nothing done here cannot be changed as needed. pic 1...I have an Offenhauser intake for later model engine with external draft tube while my engine is early model with internal draft tube so I drilled a hole in the bottom of the draft tube boss to help draw air from valve train cavity, as I was concerned the manifold would sit to close to the internal draft tube. This may or may not have been needed, but it couldnt hurt. pic 2 and 3...installed an expandable 1 1/8 - 1 1/4 rubber "freeze plug" in the internal draft tube to keep from just drawing fresh air in and right back out without evacuating the engine air. pic 4...A shopping list of the parts I used with part numbers...all parts bought from local NAPA parts house. pic 5 and 6...I wanted to utilize the draft tube port at front of manifold so I took a 1 1/4" cupped expansion plug, chucked it into my lathe and cut a 3/4" hole dead center and tapped into place with #2 Permatex, mostly to lubricate while installing instead of installing dry. pic 7, 8 and 9..Drilled plug installed and rubber grommet and PCV valve installed. pic 10...1/8" pt x 5/16" ****** installed at base of rear carb riser. This outlet was already in place...no drilling or tapping involved pic 11 and 12...hose connected at PCV valve and vacuum source pic 13... Finished side view, barely noticeable. I may tap into the p***enger side port and tee together to help balance carbs left to right if needed. After reading all the posts about how to do this I figured I may be able to save some guys some work trying to figure out what parts are needed, so this is mainly to show what parts I used with part numbers. We have a really sharp parts gal named Tammy at our local NAPA and she loves figuring out this hotrod stuff and she runs rings around the local Auto Zone high school drop outs that need to ask if you have air conditioning when trying to buy a wheel bearing. The PCV valve and grommet are Toyota Corolla 2002 items. I will be making a plate with breather to cover the fuel pump boss so the air travels completely thru the valve cavity. Finished up plug wires, looms and hookup to dizzy.....hot damn...getting close now!
Thanks for the detailed post! I hope it all works well and look forward to seeing your performance report.
That picture gallery is pretty much what I did to my 21 stud . Blocked draft tube, and ran PCV valve to manifold below carb. Also needs an air inlet - I ran a 1/2" hose from air cleaner to oil filler pipe above fuel pump. Oil filler cap was changed so only vent air is from air cleaner. Had to tinker with the idle mixture a wee bit to compensate. Has done many thousands of miles since valve installed back in the 70s - and still no drips from the rear main. Garpo
I am no expert but as you can see the PCV is a spring loaded gizmo. Since it is I don't think it matters if it is mounted at an angle.
Hmm must be Chevy ones. Ford and dodge run loose. If they don't rattle they are stuck open. There is no spring.
That rattle is a check valve that the carb va***e holds open, creating a va***e to the crank case, pulling the gases out. The sbc pcv valve is the same type, runs loose.
Exactly no spring. I have taken them apart to see what is inside. And the rebuildable vintage ones run a tapered seat and plug.
So I just pulled the engine out of my coupe........ My PCV plan seems to have failed..... Don't know what the cause is yet but the intake gasket had blown out at the back and the front of the gasket was delaminating and just about ready blow out the front. I had an oil film in the intake runners and the plugs were black from oil. The engine just has 2000 miles on it and did not smoke. We will get it on the engine stand and tear it down some more to see if we can find the source of the noise we were hearing(sounded like a rod in distress) and look for some reason for all of the oil. More later. This of course is not easy on the ego but hopefully some of you will have some ideas that will help me get it right this time.
Update: I never did find the cause for the intake gasket failure. When I re***embled the engine this time I did use some ( Hot Rod Primer) ultra black silicone between the manifold and the top side of the gasket and a better gasket. The system seems to be working fine after 600 miles. As mentioned before my system is similar to the system shown by Ron Brown in this thread. I came back to this thread because I have been following Danny's PCV thread the last couple of days. I noticed that some posters are showing the placement of the PCV valve in the road draft tube hole in the lifter valley. On my 59L block I think that road draft tube p***age goes directly through the block to the draft fitting on the oil pan. Is the 8BA block plumbed differently? Does the 8BA have a p***age in the crank case that would allow the PCV installed at the lifter valley to **** out the crank case g***es? It looks to me that it wold only be ****ing unfiltered atmospheric air to the manifold.
Below is a drawing of late 8BA flathead ventilation. Next is the '35-'48 ventilation, which flows very different than the later engines.
Thanks V8 Bob. That sort of answers my question. Do you have a larger version of those drawings that you could post?
At this time no, (because of Photobuckets new policy ) but you can enlarge them if you open the little box on the upper right of your screen and go for around 300%. They are also found on the internet-Google "flathead ford ventilation" or similar.
Thanks Bob! You know I don't even use photo bucket. I edit the pictures on my PC and post them from my files.
Just wanted to say thank you for posting this. Very concise, easy to follow, and solved the issue. Much appreciated.
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