You'd think then that he'd have more intelligent things to say.


My apologize for trying to help.

 

Gentlemen,

Many years ago, I had the privilege of working for one of the largest oil companies in the world. They were and still are very progressive. One of the reasons for the company's success was how they valued input from each and every employee. They practiced what was termed "brain storming" sessions. In such as session, a particular topic was discussed and all present had the opportunity to verbalize their thoughts [contributions]. In a particular session, personnel might be made up of process operators, technicians, professionals [PhDs, etc.], supervisors and even the CEO on site. ALL were treated equally and allowed the same time for sharing their ideas. It was accepted by the company that pooling of ideas was better than any individual idea. What happened many times was that what one individual offered caused another to have yet another [better] idea and by the end of the session, the group was closer to solving the problem. Also, what was accepted was that if any one individual belittled or in any way made fun of or questioned the validity of what someone said, then the employee who had just spoken might "cross their arms" [body language] and drop out of the conversation. The one who "dropped out" might be just the person who would have offered what needed to be heard by the group in order to come up with the best overall solution. In essence, the whole group [our forum] would have suffered a loss.


I believe we have just witnessed what has been described above.


The Frenchtown Flyer, as has already been mentioned, is a retired Mechanical Engineer who was employed by Ford. He was responsible for the development of engines and is a wealth of legitimate proven knowledge. He has a love for the six cylinder engines and has had tremendous success racing at a very high level. Not only is he well educated and highly experienced with what we as forum members dream about, but he is more than willing to share this knowledge with us at no charge. We are blessed to have him as a fellow forum member and I for one have been helped many times by his insight.


I would suggest that any and all let him know that his presence is valued, highly.


Now, let's get back to the original topic.

 

X2 1986F150six, I can't agree more.
I have been fooling with these old trucks sense the mid 60's and I still learn something new just about every day.
One thing I have learned over the years is insight from knowledgeable people is priceless.

 

X3 1986F150six. When it comes to knowledge, experience and sharing same about our engines, FTF is a national treasure.

 

Okay, 1986F150six, is this the sort of sharing of opinions you want? "I might read the other posts, maybe, if the rest of you are real lucky." He gives us attitude from his first sentence, and puts his ignorance on display in the second sentence. Why argue with attitude and ignorance?

All opinions don't carry the same weight. I have opinions on this subject, and could say, "Here is my understanding of PCV systems, and these were my personal experiences and impressions." But why do that, when I can listen to the ideas of someone who knows far more than I. Someone with access to instrumented testing instead of anecdotes. Opinions have no place in discussions of established facts. Do you need a room full of people each expressing his "opinion" on the existence of gravity, or whether two plus two equals four?

Let everybody express his opinion on something like politics; Brute could assert his views with a big dose of attitude and tell us we're all idiots to disagree, I could come back with equal certitude and belligerence, you could say we're both fools, and then we could all go off and get drunk and agree that women are all crazy.

The ideal situation here would be for Flyer to invite a fellow Ford engineer who has spent years as a PCV system specialist to come here.

 

I will attempt to retrieve two charts provided by Purolator showing the differences between two PCV valves, both for the 300/4.9L engine.


PV736 is what was specified for a 1970 F350 300 engine w/o EGR. The scale is in feet/min.


PV118 is what was specified for a 1986 F150 4.9L engine w/EGR. The scale is in feet/hour.


[note: 300 feet/hour is the same as 5 feet/minute.]


My thanks to AbandonedBronco for his assistance with adding the charts. These two PCV valves were chosen due to the fact that I drive a 1986 F150 w/4.9L engine which has been modified with Duraspark/MSD ignition, no EGR and a carburetor from a 1970 F350.






PV118



PV736

 

I to have an impressive resume of automotive experience, however I do not use it to prove my points on forums like this. Why, cause it doesn't matter, either I'm right or I'm wrong. Whether I spent 40 years working with performance engines or just picked up a wrench for the first time yesterday does not matter. Either 1+1 is 2, or it isn't, posting that I have a degree in advanced mathematics wouldn't allow me to say that 1+1 is 3. Nor does being nice make 1+1 equal 3, no matter how it's said 1+1 is still 2.


It does not matter if The Frenchtown Flyer has spent 40 years working on PCV systems. Or if he comes over to your home and personally kisses your ****. It still does not make much of what he asserted correct.

I know what I said is not the common line of thought, but at one time so was the assertion that the earth is round and not the center of the universe. I'm more then willing to discuss the merits of what I asserted but this whole jerk, grammar **** thing is ridiculous. It drops the discussion to the level of personal insults, status, and popularity over actual facts.


I'm not going to apologize for putting forth an unpopular line of thought, as it is correct. Nor am I going to kiss your **** to try and make you believe me. The OP wanted a better PCV to "set up the engine for the best economy." I volunteered my time to provide one. My time is mine to do with as I please. It's not your place to demand that I read and respect every word posted, I've read it all before, why read it again.

 

I very much appreciate this.

One thing that I have always valued about this site and others is the willingness of others to share their knowledge, expertise, experiences, etc. This alone is what has brought me from the guy who, ten years ago, barely had enough mechanical know-how to do my own oil changes to someone who has repaired/replaced nearly every part of my vehicle, done engine swaps, performance upgrades and custom tuning, diagnostics on my own and friend's vehicles, and can name about every part and explain how it works. Every single bit of it has been garnered from asking questions on forums and reading what other people have to say in response. I can't even imagine how much of my time and money it has saved me. All due to the selfless willingness of others to share.

I never want to discourage anyone from sharing what they know, or fail to let them know they are appreciated for sharing it. They certainly don't have to.

That said, I learned early on that it's best to simply share your opinion/thoughts/experiences on the matter and let others decide for themselves whether or not they want to take it. State the facts, why you believe them to be such, and let them sort it out for themselves. Too many times early on did I outright state how something was, only to find my foot in my mouth way too many times when someone called me out on it or proved me wrong.

I learned I gained nothing from being "right", but only by helping the person who's in need get the right information.

 

well put AB

 

So what's your interpretation of those two charts, F150, and what decisions can you make from them? Were those two valves made to flow differently because one is for an engine with EGR and one isn't? Or because something new was learned about how to do it over 16 years? Or because emissions regs got tighter? What's in the charts that says that if you modify a 300-six you should choose only from among valves that were made for factory 300-sixes? I see data, but no answers jump out of it.

Brute's attitude really rubbed me the wrong way, but since I don't know him, I suppose I could be seeing more attitude than he really intended. Some guys are like that. I will readily grant his assertion that a simple answer is to bypass the whole recalibration problem by going back in the direction of a road-draft tube but re-routing it to a venturi that pulls out the blowby. And I'm all for KISS. But in a street vehicle (as opposed to a race car), I'd personally rather not do too much polluting if I can easily avoid it, and one of the good things about the PCV system is that it cut total vehicle emissions by about a third all by itself, while being mechanically simple and compact.

 

Please re-read what I said though. I in no way asserted that a road draft tube is a better way to go, it's going backwards. Road draft tubes have there place, a gas pickup isn't one.

I assert that the use of a PCV valve to control flow through the PCV system is harmful. That an open high flowing connection between intake vacuum and the crankcase is better. As long as it is accompanied by the removal or plugging of the vent portion of the stock PCV system. I assert that a worth while and very simple modification that is much better then trying to find a better PCV valve. Is to simply remove the valve itself from the equation and plug the vent.

Why, with a vent and a restricted flow between intake and crankcase several undesirable things occur that would be improved by such a modification. With a restricted PCV, during high throttle conditions the PCV can't flow enough to pull out all the blow-by gasses. Thus the gasses are pushed out through the vent. This has two undesirable consequences. First a slight pressure is created in the crankcase leading to oil leaks, oil consumption, and poor ring seals. Secondly the gasses are vented into the intake up stream of the throttle. This gunks up the intake and often the filter as well as has a similar effect as having the EGR open. All of this of course gets worse as the engine wears out.

Secondly during low throttle conditions the PCV flows more then the engine blows-by. This is good, except that there is a vent, with a vent two undesirable things occur. First a vacuum is prevented from forming, a vacuum being allowed within the crankcase would help seal the rings and would all but eliminate the possibility of oil leaks and consumption. Secondly an undesirable thing is pulled into the crankcase via the vent, outside air. Outside air contains oxygen, water, and depending on the vent often dust.

This balance of too little flow and too much flow through the PCV is what modern PCV valves try to solve. However it just can't be done, the conditions and variables vary too much, nor are easily measured. More to the point I assert that there is no need to even try.

If I've explained myself well to this point you might be saying, what happens if I plug the vent. Well yes, removing the vent would remove the consequences I put forth that occur under low throttle conditions. But the high throttle consequences would be amplified. With no vent to relieve the pressure when the PCV can't flow enough the blow-by gasses would create a pressure in the crankcase. Thus the next step is to remove the restriction, thus remove the valve in order to increase PCV flow to the point that it can flow enough under high throttle conditions.

OK so overall what happens when the vent is plugged and the restriction removed. Essentially during all throttle conditions if the PCV flows enough crankcase pressure will always be a little above manifold pressure. That is vacuum in the crankcase will be a little below manifold vacuum. Flow through the PCV will always be equal to the amount of blow-by + leaks. And the vacuum present in the crankcase during most running conditions will make leaking and consuming oil near impossible while helping the rings seal.

The only time in which the crankcase will not have vacuum is during WOT. At WOT vacuum is near zero and blow-by the highest. It's also the most important running condition in which you do not want blow-by gasses in the intake stream. Blow by gasses in the intake stream is similar to having the EGR open. This is a problem all PCV systems that use the intake have. The solution is to add a second removal pathway. This would be where exhaust evacuation comes into play. More on that if you ask.


Hope this helps.

 

That's what I read. Which is why I said this:

Moroso P/N 25900

 

Yes that is in part what I was referring to from Moroso but it isn't a road draft system http://www.summitracing.com/parts/mor-25900
http://moroso.com/eb/web/instructions/25900_inst.pdf
Second link is instructions.

It could be called an exhaust draft tube I guess. Road draft tubes use the air flow under the vehicle, this uses the exhaust flow. Road draft tubes only have any benefit at speed, this works at any speed. Road draft tubes vent smoke under the engine, this blends it with the exhaust so it leaves out the tailpipe. Road draft tubes don't create much suction, I've seen these setups keep the oil in a pan with a quarter size hole due to all the suction. More important at WOT when the PCV system is useless, exhaust evacuation is at it's best no matter the speed of the vehicle.

 

I was reading this thread with great interest, then I read the Summit description on the Moroso item. Drag racing only, cannot be used with mufflers, OK that's not for me. I will just start with the PCV that is for the early (1970) engine. PV 736. I'm going to write that down now.

 

They have to say that, it's a legal thing, they are not CARB/EPA legal. I've put plenty up stream of mufflers. You can't however put one up stream of a catalytic converter, the oily gasses will likely plug the converter. In that case though you just put it down stream of the converter.


EDIT..
To be fair though they should not be put up stream of a highly restrictive muffler. The backpressure would defeat the purpose of it. Again though just put it down stream of the muffler, it wouldn't work as well but would work.