PCV Valve

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My last engine rebuild was pretty radical.  I built a home brew de-stroker using a 390 block and 343 crank and rods.  I used 13:1 pistons to get a static compression of 10:1.  The cam was pretty wild for a street car with about .548 lift and lots of duration and overlap.  My problem was I had such low vacuum, the PCV valve pretty much stayed open and suck a lot of oil into the intake and kept fouling one plug (No. 6, I think) nearest the valve.  Has anyone had any experience and have solution to this?  I'm getting ready for another rebuild, 390 this time but with lift of a little over .500.  I think I may have to design my on PCV valve because I see no cheap way of eliminating it.
Thanks for the help!
Joe
ps; it would rev to 7200 rpm in a heart beat!

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joelash1 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Dec/01/2010 Location: S. Alabama Status: Offline Points: 21	Post Options Post Reply Quote joelash1 Report Post Thanks(0) Quote Reply Topic: PCV Valve Posted: Jun/04/2018 at 8:45pm
	My last engine rebuild was pretty radical. I built a home brew de-stroker using a 390 block and 343 crank and rods. I used 13:1 pistons to get a static compression of 10:1. The cam was pretty wild for a street car with about .548 lift and lots of duration and overlap. My problem was I had such low vacuum, the PCV valve pretty much stayed open and suck a lot of oil into the intake and kept fouling one plug (No. 6, I think) nearest the valve. Has anyone had any experience and have solution to this? I'm getting ready for another rebuild, 390 this time but with lift of a little over .500. I think I may have to design my on PCV valve because I see no cheap way of eliminating it. Thanks for the help! Joe ps; it would rev to 7200 rpm in a heart beat!

mixed up Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jun/16/2015 Location: Monroe mich Status: Offline Points: 2178	Post Options Post Reply Quote mixed up Report Post Thanks(0) Quote Reply Posted: Jun/04/2018 at 11:58pm
	tha question is do the aftermarket intake you run have the baffle in place if not then you need to install them the baffle alone will solve your problem I run a 540 lift on my 290 with no issues
	69 amx 290 auto 65 220 290 4spd 80 ford fairmont

ccowx Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510	Post Options Post Reply Quote ccowx Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 2:37am
	I recently posted a thread on this very problem here. I have an old school group 19 cam, which is less radical than yours. Problem is that it has a lot of overlap and that is what gives a low vacuum. I also have had issues that I suspect are the PCV valve sucking oil. I assume you have the correct baffle and metal pan gasket in your engine? Without those you will probably always have oil loss issues. If you do, then possibly the PCV is hanging open. My solution was to use a dremel and take a stock pcv apart and then grind the spring inside to a smaller diameter. My precision instrument to measure my results was putting a small bottle of tobasco sauce on it and see how far it compressed after grinding. I have not done enough driving to have results yet. Another option is to get an adjustable pcv valve. I forget who makes it, but they are available. That way you can adjust it for proper function at whatever vacuum. Chris

jcisworthy Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805	Post Options Post Reply Quote jcisworthy Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 5:35am
	Install a 1" core plug in the PCV hole and forget about it
	Specializing in dyno services, engine building, and cylinder head porting rbjracing.com Phone Number 518-915-3203

Bandana Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Jul/26/2016 Location: NC Status: Offline Points: 473	Post Options Post Reply Quote Bandana Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 9:09am
	Was just going to post something on this when I saw this post. I’m kind of wondering the same - if my oil burning issues are PCV related. I just had a fellow check my compression and leak down and supposedly all was good.... (165 psi and even - 8% leak down) Rings have 1000 Miles or so on them so they should be seated by now? I have a new PCs in it and it’s not sticking. I don’t have a vacuum gauge - yet, but I suspect I’m running low vac as I have a .520 lift cam. I'm definitely getting a lot of oil into the PCV as its always pretty wet. Prior to letting someone try to "tune it up" I had installed a catch can on the PCV line and it was filling up fast. I may put it back on and at least keep the oil out of the intake until I can figure out why its pulling so much up ... Edited by Bandana - Jun/05/2018 at 9:21am

ccowx Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510	Post Options Post Reply Quote ccowx Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 10:06am
	JCIS,you can run without a pcv if you like. I would not(and I have in the past!), but you get dirty oil faster and you will lose a small amount of horsepower. As for cams and vacuum, again, it is not lift that does it, it is overlap. I have a friend with a cam in his 360 that is .528 lift and he is pulling around 17-18" of vacuum. Your wet pcv issues could be the valve or the baffling or the pan gasket. There is a chart in the TSM showing vacuum and what kind of flow the pcv is giving at a specific vacuum level. If you know your engine vacuum and take a look at the chart, you can get a fair idea of how your pcv system should be working. Thanks! Chris

Dirtydog Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Nov/20/2017 Location: Harleysville PA Status: Offline Points: 67	Post Options Post Reply Quote Dirtydog Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 11:32am
	I did a post it was called Low vacuum using oil it turned out that I had no baffle plate and I had no pan gasket Scott one of the members. help me out and said take a screwdriver and Stick It Down the PVC hole you will have to pull out the rubber grommet if you have more than 2 and 1/2 in you have no baffle plate also then if you get a longer screwdriver and rub it around down there it should feel smooth if you have a pan gasket if you feel roughness no pan gasket try that first haven't gotten mine on the street yet to see if I corrected the problem but I'm going in the right direction

jcisworthy Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805	Post Options Post Reply Quote jcisworthy Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 12:00pm
	CCOWX, I would rather not introduce dirty air in the intake charge and if there was any power loss it will be so negligable it will never be noticed. When the oil gets dirty it gets changed anyway. Oil and filters are cheap. When this next engine goes on the dyno I will make a pull with and without the PCV and see what happens.
	Specializing in dyno services, engine building, and cylinder head porting rbjracing.com Phone Number 518-915-3203

Greyhounds_AMX Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268	Post Options Post Reply Quote Greyhounds_AMX Report Post Thanks(0) Quote Reply Posted: Jun/05/2018 at 1:14pm
	I would challenge you to to run the engine for 50,000 miles on the street with out a PCV valve and show me that the rear main didn't leak. But more to the OP's questions, definitely keep the catch can. Any bit of oil in the intake charge will drop the effective octane rating of the fuel so whatever you can do to pull out the oil is worth the effort. We should all run a catch can.
	1968 AMX 390 w/T5

billd Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894	Post Options Post Reply Quote billd Report Post Thanks(1) Quote Reply Posted: Jun/05/2018 at 1:26pm
	You want VACUUM in the crankcase. It helps seals, and it helps seal rings and helps HP. Ever notice some guys run vacuum pumps for the crankcase? The PCV does more than just suck fumes out of the crankcase - you have less acids, the oil stays cleaner longer (I worked on engines when there were still a lot of cars around without the PCV and there's a huge difference in the engine life, life of the oil, how dirty it was, sludge buildup under the valve covers and in other areas and so on. Maybe Iowans just held onto cars longer but even I had to deal with the road draft tubes quite a few times when doing engine work.) They do make devices to trap the oil so you can run the PCV and not have the oil sucked into the intake. Chris - LSA, lobe separation angle - I had to keep mine to about 113 on the Eagle to keep the vacuum up for the MAP sensor and the factory injection.
	http://theamcpages.com http://antique-engines.com