Anybody old enough to remember this ad? That's what happens in engines run infrequently that still use an original crankcase vent tube instead of a modern PCV system. A properly operating PCV system creates a vacuum in the crankcase and draws the airborne contaminants into the engine to be burned and expelled along with the exhaust. Without a PCV system, water vapor and combustion byproducts remain in the crankcase, mix with the oil and form a thick, lumpy tar-like crud that is almost impossible to remove without dropping the pan and s****ing it out. Modern engines deal with this problem with a PCV system, but what about older engines, especially Y-blocks and flatheads where modern components cannot be easily retrofitted as they can on some other engines? So... Let's see what our members have come up with to overcome this filthy problem.
I was wondering how to retrofit my stock 8ba setup to accomidate a pvc system. I have only seen it done when a aftermartket carbuerator (4bbl) is in place. Looking forward to seeing some solutions.
Y Blocks are easily retrofitted with a PCV system. Ask Raceron for some pics of his Vicky's 292. So is any other engine using a road draft tube.
There is a guy in Canada that sells a PCV retrofit for the flathead. He sells them on eBay ... I'd post a link, but there are no active (or recently active). I picked up one of his kits for $30. Basically, you remove the draft tube and he has machined an aluminum insert that presses into the hole with a PCV valve attached to it. Then a hose that routes to a T-fitting that plugs into the vacuum port at the base of the carb. It essentially uses the same drafting path as the draft tube but only it forces it via vacuum.
streetdreams Y Blocks are easily retrofitted with a PCV system. Ask Raceron for some pics of his Vicky's 292. So is any other engine using a road draft tube. I snuk into Ron's album and looked at every photo of his engine and I couldn't see a PCV setup. How does it work and how did you conceal it?
All you do is block off the original draft tube. Then you can drill a hole in the valley cover, or it should work in the top cover(rocker cover), install a rubber gromet, and put a PCV valve in the gromet. Get some rubber hose and take it to a vacuum port at the base of the carb, or in the intake. What this does is causes a vacuum in the crankcase, ****ing up the fumes.
Sorry I don't have better pics, but this gives an idea of how John set up the PCV on my 292. Before - this is the '55 Mercury 292 as I got it (draft tube still in place): After John blocked of the port (behind fuel pump) & rerouted the vent using PCV valve: Back of engine, showing routing from carb base plate to valley pan: Eric I remember that old Purolator ad, yours with Donald O'Connor. I posted one awhile ago with Joe E. Brown; I think Puro ran it using various other celebrities as well.
The TBird parts suppliers hava PCV kit that includes a plate that goes between the carb and intake which has a ****** on it, hose, valve and grommet. You have to drill a hole in the valley cover if you don't have the TBird valley cover. Units for both the early 4bbl and the later (57) 4bbl.
It's best to fabricate something to hold some steel or aluminum wool to serve as an oil vapor catch. Otherwise, you may pull enough vapors into the intake system to get a puff of blue smoke now and then, especially on a tired engine. When I built Ron's 292, I fabricated a strainer out of 1 3/4 inch thin wall steel tubing, with multiple holes drilled throughout it, including the bottom floor of it. That got welded to the underside of the valley cover, in the rear where the road draft tube would attach on a TBird, or where there is just a flat spot on p*** car units. With a drilled hole sized for a grommet to install the PCV valve, you're all set. This also allows for removing and replacing the strainer material in the future if required. You need to install the PCV in the back, not the valve covers, because the cover has a divider plate centered internal in the lifter valley. This somewhat divides the crankcase in two, which forces the air going in through the filter breather/filler cap to circulate throughout ther engine and come up through the rear half of the crankcase, then out the draft tube, now a PCV system. ON a p*** car, it circulates and then exits front left of block. You should also try and use a PCV valve sized and designed for something close to your engines' crankcase volume, or you may over/under draw the crankcase. Neither is good.
Yeah the back of the valley cover is the obvious way to run a pcv. I've got mine going intro my intake directly, and it works well. I'm using a pcv for a SBC on a couple of cars, and they seem to work okay. I've played the game of road draft tubes and I'll never do it again!
...speaking of crankcase vent tubes...is it normal for a small amount of oil to seep out of it after the engine has been run awhile?
No. There should be some strainer material to capture the oil so's it doesn't drip out. You may also be pushing the vapor out with too much crankcase blowby pressure. Check your oil fill cap. It should be the vented type and should be clean to let air flow. If you run the engine with the cap off and get a lot of smoke coming out of it, you've got a tired motor with most likely worn rings.
John I think you're talking about that mesh-type filter that goes in the top of the draft tube? Most people don't know they're there. I took it out of the original engine, it looked like that one in Eric's Purolator ad.
Mr. Tomato Head ...speaking of crankcase vent tubes...is it normal for a small amount of oil to seep out of it after the engine has been run awhile? What you are actually seeing is probably a mixture of oil and condensed water vapor - the two elements of crank case contamination. It can be anywhere from black to a tan color. This fluid drips out of the road draft tube as the engine cools and the vapor condenses in the tube. A small amount is normal for a car with a road draft tube. The more worn the engine, the more crank case contamination (blow-by) it will produce. The more contamination produced, the more smoke and condensation will issue from the road draft tube...and collect on the ground after the engine is shut off. The fluid which escapes is nothing compared to what remains in the crank case and turns into the black or gray gunk I spoke of earlier...the stuff in the filter adverti*****t. The Positive Crankcase Ventilation system ****s this byproduct vapor out of the crank case and introduces it into the intake where it goes into the engine and is burned. This keeps the inside of the engine much, much cleaner and extends the life of the oil and filter as well. Adding a PCV system is a really good idea for both stock and modified engines. Hope this helps.
If you run the engine enough, all the wates vapor is burned off and you don't have to worry - especially now with the better oils.
Thanks guys. This 272 was just rebuilt a year ago. It's got less than 500 miles on it. That puts my mind at ease...
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