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By PWH42 - 18 Years Ago
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I recently installed a PCV setup from a 64 truck on my 56 272 and removed the draft tube breather and used the block-off plate from the truck.Since doing this,the engine is blowing oil out of the filler cap.This is a low mileage engine that has never used oil and does not show signs of blow-by when running.The PCV is installed the same as it was on the truck and includes a new valve.Anyone have any suggestions about the cause of the oil out of the filler???? Thanks
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By Canadian Hot Rodder - 18 Years Ago
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You say the PCV is new, could it possibly be stuck? Also make sure it is pointing in the right direction of flow, I know I almost put mine in backwards. Where did you tie in the PCV, the base of the carb? If so do you have a good vacume draw there? Just some thoughts. Rob
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By MoonShadow - 18 Years Ago
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If you can, reverse the PCV and see what happens! They can go in in reverse. Let us know what you find. Chuck
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By DANIEL TINDER - 18 Years Ago
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Paul,
Just curious, but what kind of filler cap are you running? When I was using a K&N with a tight rubber seal, it dripped oil constantly. After I switched to an original style repro with open-cell foam, it stopped.
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By PWH42 - 18 Years Ago
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I have the valve threaded into the intake manifold,as it was on the donor truck.These valves can't be reversed as the later model one can.They are threaded on the end that goes into the vacuum source.As far as being stuck,I don't think so.I have taken it all back apart three times and checked.The filler cap is a chrome aftermarket one that I found on a parts car I bought a few years ago.It's got a cork gasket and is filled with coarse steel wool.My vacuum guage shows a good strong vacuum where I put the valve. Thanks,everyone, for all the suggestions.I'll go back and recheck everything,maybe try a different filler cap.
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By Glen Henderson - 18 Years Ago
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I am using the same setup on my 292 and have had no problems, works great. I did use the valley pan from the 64 engine too. The only thing that I can think of that would keep it from working properly is that the long tube going to the valley pan or the tube from the valley pan is clogged. I know that when I installed my unit I had to take a welding rod and dig the gunk out of it.
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By PWH42 - 18 Years Ago
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Thanks Glen, I also used the truck valley pan,but I made up all new lines as I am using the port in the rear of the manifold for vacuum instead of the one in front of the carburetor like the original on the truck.
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By pcmenten - 18 Years Ago
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...as I am using the port in the rear of the manifold for vacuum...
Is that manifold the ECZ-B 4bbl intake? One or both of the little holes drilled into that port (one hole goes to one side of the intake, the other to the other side) might be plugged up. How much manifold vacuum do you have? Did you enrich the idle mixture screw (and turn down the idle speed) when you plumbed the PCV? I'm thinking that adding PCV would lean out the mixture. And I'd check to make sure that the PCV valve itself doesn't cover those little holes when it is seated in the port.
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By Glen Henderson - 18 Years Ago
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pcmenten brought up a good point and it got me too thinking, so I just got back from the barn digging out my stash of B intakes. The setup that I am using is on a two barrel intake and is in the stock location and works great, but the B intake does not have the port in the top of the intake like the two barrel intake does. I looked at three different B intakes and all three off them had the two little holes in the rear. They all had at least one of the holes plugged up with carbon. I then pulled a B intake that I have had hot tanked for a engine that I am getting ready to build and while the holes looked open from the outside, when I ran a welding rod down them I knocked out carbon. They are not very big and could be plugged. Also as he suggested the fitting that you used could very easily be blocking the ports.
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By PWH42 - 18 Years Ago
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I have not physically checked the holes(incidentally this is a 4 barrel B intake),but I just put a vacuum guage on the port I'm using.It shows 19 inches at idle and recovers to that point after revving up.I am tempted to run this car without the valve,that is just run the vacuum line from the intake directly to the valley pan.Anyone know what will happen in this case?????
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By Hoosier Hurricane - 18 Years Ago
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Those little holes could be closed down to very small holes and still give a vacuum reading, but would not flow enough volume of air to scavenge the crankcase. John
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By GREENBIRD56 - 18 Years Ago
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I've been thinking the same thing as John - you guys are putting vacuum on there - but no flow capacity. Look at the size of the PCV port on the Holley 4160 carbs - must be 5/16 - 3/8 opening? You end up compensating for this big hole with your idle and fuel jetng too. The PCV valve is a reverse "check valve" that prevents pressurizing the crankcase with a backfire (at least that's what I was taught).
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By MoonShadow - 18 Years Ago
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Basicly you shouldn't be able to blow through it in the direction of the crankcase. As I learned the hard way! Chuck
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By Glen Henderson - 18 Years Ago
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I agree with you guys, after looking at my intakes, I don't think that this is a good place for a PVC valve. Those ports are just too small, could they be opened up some without affecting the flow on the rear runners, don't know, but I think that a carb spacer with the proper sized nipple might be a better solution.
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By M_S - 18 Years Ago
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I have been following this thread as I have the same problem with my engine. I put the PCV on in place of the road draft to hopefully cure the dribble of oil from the breather on to the valve cover. It helped but I do still get oil dripping on the front of the VC. I am using the 5/16" port on the base plate of the Demon to a PCV that I mounted in the stock valley with a plastic elbow. Just wanted to add this due to the conversation about PSI v. flow.
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By GREENBIRD56 - 18 Years Ago
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I think Holun put a little more modern PCV on his set-up at one time. The breather port cap at the front of the engine (where we are running the open style) is closed and piped to the air cleaner. If the engine doesn't get enough vent from the vacuum port - it feeds it down the venturi. Could be thats the only way we'll get a completely clean system.
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By PWH42 - 18 Years Ago
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After a little thought,I must agree with all of you about the lack of flow volume.For now I think I'll just re-install the draft tube and leave the PCV as is.Maybe the two together will stop the slight drip I used to get from the tube.This winter I'll figure out a proper solution.It's too hot now for strenuous brain activity. Thanks for all the help.
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By miker - 18 Years Ago
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Just one added thought. After several years of running a PCV system on a stock motor, I moved it to a larger motor with a high flow oil pump. The duck bill style baffle I had on the valley pan (PCV side) didn't control the oil splash off the dist. gear, and I picked up enough oil to send the engine into detonation and blew the left side head gasket twice. I welded a better baffle under the valley pan, and have not had the problem since, so I think that was it.
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