Crankcase Pressure

[xctasy]

I'm backtrackin'. Trust your engine builder, follow his advice.


That engine is sensational, well done.

Your engine is typical of the best aftermarket systems; it will be noisy as it has no effective silencing with that free flowing cotton strand air cleaner, and "fumey" (there is no means of managing blow by which will certainly be more than 2 cfm at 4000 rpm).


So you'll hear and smell everything.

I'd be looking at Option 4, DV's Evacusump as listed in the two book related posts above. Or one of the lower tier options 1-3.



Don't beat on it too much until its run in.


Your engine will be making one hang of a lot more mid-range, and the oil and blow by and soaking might be noticeable at high rev's, but the top end could be being drowned at as little as 3500 rpm depending on cam type....your rocker covers don't have baffles. And they won't stop a bath of that much blow by related oil....


All fresh, out of the ordinary builds like this have non standard parts that don't have the standard details of a production part. Noise suppression, silencing, oil control via a Federally approved PCV system, none of it is there, its all just pure, no holds barred performance engine. And I totally approve.

I've dealt with blow by problems on most new performance rebuilds....you fix it by going back to those basics. Factory style under hood snorkels, factory baffle under the PCV like most of the stock rock covers had, and a balanced PCV are a start.


One guy here has an Atomic EFI with a stock twin snorkel air cleaner with two variations. Stock twin snorkel drops out past 600 cfm, so his has larger pipes and two pancaked oval intake ports to the air cleaner....although it looses a little appeal, it aces the class for noise suppression and heat soak.

EFI engines really do produce the goods..a little more of everything. But you'll notice other stuff....

[xctasy]

For the noise suppression matter, I didn't have any luck with finding the guy with the Atomic EFI and custom dual snorkle. I think he used one of these.

Oh. See below, found it!


BMW Rider's re-use of the basic Guest 1985CapriGS air cleaner, the
Spectre air cleaner assembly.

Got a call this morning and my Spectre air cleaner was finally in. I'd ordered it back in early November, but it was on back-order. Thanks to Darran (82GTforME) I scored the two air tubes that fit under the fender to draw the cold air up in trade for my fender liners. The air cleaner has flanges that mounted to the skirts in the engine compartment and flex tubes to connect to the air cleaner. It's kind of like an aftermarket version of the HO dual snorkel air cleaner. I did have to add an extension ring to the base to raise it up high enough off the MSD EFI throttle body. That was a fairly simple job to cut a strip of tin form it into a ring and weld it up. The right tube just barely tucks under the MM strut brace, but it looks pretty good I think. The EFI cam with a nice decal that I applied to the lid. I'm not usually one to put decals on anything other than my toolbox, but I liked the way this one looked. Kind of like those sixties muscle cars. Also grabbed a nice Ford logo wing nut to hold it on.

Eliminating the air cleaner flow rate,


the 17" external 460 Truck / CFI/4BBL 4V 83-85 3" dual snokle air cleaner flows 535 cfm at the operating pressure drop.

It has a 14 inch element, up 1 inch on the taller 15 " external 82 2V GT's dual inlet housing.

The Ram Air Box by apparently flows a claimed 916 cfm, but it is a lot taller with a 4" tall element inside.

Figures are: http://www.ramairbox.com/flowtest.html




see http://www.ramairbox.com/models.html


Others have a 180 degree inlet angle. the above, 135 degrees.

http://vb.foureyedpride.com/showthre...el-Air-Cleaner

blue beast's



Guest 1985CapriGS




jaz50's

you mean this?
Emile's Mustang.

[erratic50]

I am certain some of those setups are nice and quiet while others moan like the hood is about to also get sucked in during the task of making horsepower.

I ran a Carter with an open element and no sound deadening "hood insulation" on my Galaxie - and guess which camp I'm in? Lol. Nothing like a good sounding loud induction setup paired with good sounding loud exhaust. Just my opinion. That's the main thing I miss about my pre-EFI days.

[erratic50]

Not uncommon for a such a long stroke in a short deck height block. Would be very bad news.

Good luck getting the problem solved.

[erratic50]

What ever became of this problem?

[Ethyl Cat]

Seconds blow-by, but PCV isn't part of the equation at all at WOT (I suppose unless it's stuck open). Leak-down or compression tests tell what's up with compression rings, but aren't going to indicate the health of the oil control rings. Take the spark plugs out and look at them for a dark/wet/oily appearance. Anything slapped on would just be addressing symptoms instead of fixing the problem. An oil control problem will need whatever is wrong with the oil control rings corrected.

The PCV valve is a variable orifice calibrated to increase flow as the engine is generating more blow by.

It flows the most at WOT and the least at Idle due to a calibrated internal spring. It seals against reverse flow in the case of boost and backfire.

It is VERY important NOT to get a universal PCV valve. Get a PCV that is calibrated as closely to your engine as possible.

Make sure that your valve covers have a baffle in them under to fill and PCV openings.

[Walking-Tall]

The PCV valve is a variable orifice calibrated to increase flow as the engine is generating more blow by.

It flows the most at WOT and the least at Idle due to a calibrated internal spring. It seals against reverse flow in the case of boost and backfire.

It is VERY important NOT to get a universal PCV valve. Get a PCV that is calibrated as closely to your engine as possible.

Make sure that your valve covers have a baffle in them under to fill and PCV openings.

The PCV valve? Variable (there are fixed-orifice and adjustable valves too) is a good word to use for this subject, generally. Variation is another, like no two identically-built vehicle combinations will normally ever generate the same amount of idle manifold vacuum, vacuum levels in all varieties of load in the rpm range, or vacuum (or complete absence of vacuum) at WOT, produce the same amount of blow by, or the (wide) tolerances on mass-produced orifice sizes and installed spring heights and pressures in even purported calibrated-for-your-engine valves, etc. So, in an honest effort to skip generalities, the question becomes which valve, on which engine and vehicle combination, with what PCV function, and with how much blow by?

... and if WOT vacuum happens to be at or near zero? I wonder which evacuates more blow by (if much or much of any exists) from, or very generally, air movement through the crankcase, manifold vacuum to the intake manifold, or airflow through the filter/breather & crankcase & PCV valve & hose to the intake manifold? Along the lines of what I think I just read: if I add more PCV valves, I gain WOT CFM? I know for certain I'd gain increased idle airflow...

I think it's safe to say that if you do not get an adjustable valve that you tailor to your combination, all you can have is a mass-produced universal valve.

[JACook]

There is a popular misconception that a PCV system has no draw at WOT. And this is often the case with
many aftermarket implementations, because of the misconception. Lather, rinse, repeat.

A properly implemented PCV system will have it's connecting passages perpendicular to the main airflow
stream (after the throttle valve(s) of course), such that at WOT, the air stream will induce a low pressure
in the PCV passages. Combined with the properly calibrated PCV valve mentioned above, and a filtered,
low-restriction source of make-up air, crankcase purge happens in all operating modes, except boost.

A PCV valve that is plumbed into a single manifold runner, or the vacuum tree, will not provide the same
benefit. Likewise, using the secondary-side PCV nipple provided on many generic Holley carbs, will only
provide full benefit when the secondaries are open.

Like so many seemingly simple things, you need to take a total system approach to PCV implementation.

[Ethyl Cat]

... and if WOT vacuum happens to be at or near zero? I wonder which evacuates more blow by (if much or much of any exists) from, or very generally, air movement through the crankcase, manifold vacuum to the intake manifold, or airflow through the filter/breather & crankcase & PCV valve & hose to the intake manifold? Along the lines of what I think I just read: if I add more PCV valves, I gain WOT CFM? I know for certain I'd gain increased idle airflow...

It seems to me that you are under the impression that the crankcase has no pressure in it until blow by fills it up. It has access to atmospheric pressure at all times.

Atmospheric pressure is going to be forced into a cylinders low pressure during the intake stroke whether its thru an open throttle or a pcv hose.

"Along the lines of what I think I just read: if I add more PCV valves, I gain WOT CFM? I know for certain I'd gain increased idle airflow..."

I think you answered your own question there.

[xctasy]

Blow by is at a maximum at maximum Volumetric efficency with a wide open throttle, when stitching up that corvette in the outer lane on the highway, not always at maximum rpm. Its a very complicated matter which EFI fixede by its two methods of upstream control. For carbs, it is a really complex matter. I think I've gotten most of it worked out, but get wrong with no baffels and the wrong PCV valve, and you can literally feed oil into your carb system not even at wide open throttle.

It was the 1980, 81 nand 82 California emissions that forced carb markers to do some seriously wired crap to simple 1, 2-bbl and 4-bbl carb bowl vents and PCV systems Ford started in 1979 with optimized PCV systems that weren't even listed as so on the VECI diagrams. from 79 to the last year a carb was legal, Ford were forced to balance the Postive Crankcase Ventilation systems, and carb cars had to get a whole layer of extra crud to even operate.

The CFI V8's, port EFI 5.0 got a different PCV system to the carb 4-bbl HO engines ....and effectively except for I think, Chrysler's Omini, every Holley Weber 2-bbl system became illegal over night.


Couldn't understand how a 1981 European emissions 2 liter Ford wolud have one kind of Weber with no bowel vent hookup and bleedback fuel supply,




and for the same 1981 US Ford had to have all this.




All due to the PCV blow by issues, and how they influenced the air fuel ratio of carbs.

[Walking-Tall]

It seems to me that you are under the impression that the crankcase has no pressure in it until blow by fills it up. It has access to atmospheric pressure at all times.

Atmospheric pressure is going to be forced into a cylinders low pressure during the intake stroke whether its thru an open throttle or a pcv hose.

"Along the lines of what I think I just read: if I add more PCV valves, I gain WOT CFM? I know for certain I'd gain increased idle airflow..."

I think you answered your own question there.

Not at all... and the crankcase has access to highest intake manifold vacuum at idle, and/or at "cruise", metered thru PCV. If the common size 3/8" PCV plumbing and the supposed 90-degree-to-induction-airflow signal "orifice" were smaller, and jutted out into the air stream with a 45-degree slash cut signal tube like the ones that signal the bigger vacuum secondary carburetors to open with airflow (best-practice-theory-in-stone, prior to bean-counters as opposed to scientists/engineers dictating manufacture) used to be manufactured correctly, and very effective, then I'd agree that PCV airflow at WOT would have sensitivity and might approach crankcase blow by evacuation of significance.

Hmmm... loaded guns, these generalized statements, lol

My question? No, my question, based on your statements, remains unanswered. WOT CFM airflow and idle CFM airflow... two very different things. Your statements about how much and when (most at WOT and least at idle) THE PCV flows... that if multiple PCV valves would increase (divide would be a better word, since adding potential induction CFM, like installing a bigger carburetor, does not directly add engine airflow capability, but a smaller carburetor certainly will reduce the airflow an engine's capable of moving) the engine's WOT airflow CFM, therefore lowering WOT vacuum, etc... was my question.