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dazedduster

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Alright, I Was At My Friend And He Was Giving Me Crap For Driving A Mopar So When I Left His House I Decided To Give Him A Taste Of Why I Drive One, After A Brake Stand A A Hell Of A Burn Out I Drove The Mile Home I Got There And Noticed Oil Dripping Poped The Hood And My Engine Is Covered In Oil And I Can See The Dipstick Pushed Out Of The Tube And Its Obvios From The Pattern Thats Where The Problem Is. When I Get On It It Blows Oil Out Of It, I Did Not Notice The Problem Before I Switched Carbs Could I Have Plumed Something Wrong, Runs Awsome Plenty Of Power What Do You Guys Think.
 
ok, so your mopar has excessive crank case pressure. Answer Adam...hows your PCV system?
 
I had the same problem when I swapped the valve covers on a old 77 monaco. I had to drill holes for the PVC in one and the breather in the other.
 
At full throttle the PCV valve does not work, it only works in vacuum situations like cruising for example. You need good breathers to vent the crankcase pressure at wide open throttle. But if you motor is getting tired and you are starting to get excessive blow-by then you can't hardly have enough breathers. The comression rings control blow-by, they could either be getting worn or when you did your burn out if you rev'd your engine pretty hard you could have broke a ring or two. The correct way to find out whats wrong is to have a leak-down test performed on your motor it will tell right away whats wrong.

Chuck
 
i did not rev high, engine has 10,000 mi approx, although i did not rebuild myself. do have a breather, yes my spelling sucks along with my typing. i will preform the leekdown test next weekend.
 
hi, you commented, it didn't do this till after you changed carb. is this new carb bigger and jetted richer? some times, a very rich mixture will wash walls down, and create blowby. then again, rings could have gone away. leak and cranking compression test will tell you that.
 
well, upon inspecting the breather and pvc i noticed a milky substace in the valve covers, so yes water in the oil, what do you think blown head gasket, cracked head block either way im screwed. gess i'll have to pull it apart
 
If you rarely drive it, and it's parked outside, I wouldnt worry much about some goop under the breather. It's typical condensation stuff. the engine has to get hot enough regularly to evaporate the condesate out of the crank case. It happens a lot in the northeast. If the dipstick and waste oil drained look good (meaning not cloudy or light colored) then I would tear into it. Clean the stuff off, and drive the car a bit. Also, dont get int he habit of "warming it up" once in a while. Leave it shut off, or run it and warm it up well every time.

340, the PCV functions as long as the engine is turning on it's own. If it didnt, we'd have oil vapor all over every time the throttle was mashed and the rpms came up. It only seals off if the engine backfires out the carb. Otherwise, it's open.
 
Moper, at wide open throttle an engine has zero vacuum. Vapor can't be drawn into the intake without vacuum. When a pcv valve is at rest it is closed with a light spring and if the breather on the other valve cover can't handle the crankcase presssure it will push this spring open and send pressure thru the pcv valve. But it is not drawn in by the engine running it is pushed in by the pressure.


Chuck
 
Perhaps we are just looking at it diffrerently. If there is no vaccum reading at WOT, there is no pressure differential? More importanly, in a vaccum secondary carb...how do the secondaries ever open? There is always a pressure differential. Zero inches of vaccum on a gage indicates 14.7psi (at sea level) pushing down on the carb. In the PCV, like the vaccum secondary port, it is the motion of the airflowing past the port in the base plate, rather than the sucking of the pistons, that creates the lower pressure.The valve is set up to provide more air flow as the vaccum drops. So in situations where blow by is the worst (low vaccum, climbing hills, towing...basically under load) the valve will move the highest amount of gasses It always flows some at WOT. It's just not pulled in by the same force.
 
The vacuum secondaries open when the motor starts to pull vacuum. When the primaries are wide open the vacumm is zero as the rpm of the motor rises it will get to a point were it tries to draw more air than the two primary butterflies can supply, this starts to create a vaccum. Once the vacuum gets high enough to overcome the secondary diaphragm spring the secondaries start to open. They sell different secondary springs so you can tune at what vacuum you want your secondaries to open.

It is true about the atmospheric pressure at zero vacuum or zero psi but that atmospheric pressure is the same in both the intake and crankcase(as long as there is no crankcase pressure). The pcv port is just that a port, it is not a booster which works with air passing thru it. The only way vapor passes thru the pcv at zero intake vacuum is by positive pressure in the crankcase pushing it's way to the zero pressure environment of the intake manifold. Nothing that runs off of vacuum works at zero intake vacuum, vacuum advance, brake boosters, EGR valves, pcv valves, etc.

Chuck
 
hi, here is a story about no vacuum in a motor. four stock eliminator motors were built with the total seal gapless top rings. two were put on a dyno for break in. the motors were sealed and a blow by meter installed. when running motors, there was no blow by, yet they smoked out the exhaust profusely!
both were torn down, rings thrown out. another stocker had same results. same fix, throw out rings. last guy had no problems with oiling at all. the comman thing the 3 had was, a PVC valve installed. the rings created so much vacuum in motors, was pulling oil through motor. total seal says, to plug the PVC or have a .060 hole in line to prevent oiling. these motors pulled
oil at wide open throttle. the piston /ring does provide a vacuum. the last motor was tested and pulled 19" of vacuum at 1500 RPM. this is with a very long duration cam. when tested with regular rings was only 9"
 
This means the motors had vacuum in their intakes at wide open throttle which is possible. I was basing my explanation on the carburator being big enough that it would flow more air than the motor. If a motor tries to move more air than the carburator or throttlebody can supply this will create vacuum. A stock eliminator motor can easily move more air than the carburator because you are limited to stock carbs in that class. Nextel Cup cars when they run a restrictor late race have vacuum in the intake because the motor tries to use more air than the restrictor plate allows into the intake. I should have been more specific and not so general on the wide open throttle thing because you can have vacuum at WOT and just stuck with if a motor has zero vacuum in the intake.


Chuck
 
Well an update, I pulled the pcv out of the Breather and ran it semihard, no problems
however when i shook the pcv valve water ran out, so now i need to figure out where all the moisture is coming from
 
hi, well, these stocker motors all have 750 cfm carbs, which is more than enough carb flow! in fact ,one is a 780 holley, on a aluminum factory hi rise manifold on a 350 C.I. motor. plus the 3 motors had tricked up stocker carbs, which will flow more than rated flow is.
 
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