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ZDreamin72

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That would be a huge help if you dont mind!

- Greg -

 

The cleanest pic I have is with the engine out. This thing sits just below the coil. That bottom nipple goes to the small nipple Y'd off the crankcase vent. The top one went I believe to the back of the stock air cleaner. But since I switched to the dual webers some 15 years ago that is coming from memory.

 

vent_switch.jpg

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The loose wire hanging next to your radiator on the passenger side is for the Factory "Trouble" Light

 

As far as the rest of the descriptions go, they were all spot on, however...forget about the switching valve...they are all corroded and non functioning by now (most of them). Cap off the nipple at the crankase breather and just run a line from the vent tube to the back of the air cleaner. DO NOT BLOCK THAT LINE. If you do, the fuel tank will not vent, therfore with a full fuel tank and hot weather you will see fuel seeping from the Fill cap.

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I use the "flow control valve"(FCV) as a vacume breaker for my superduper crankcase vent system...

 

I have Hooked the small nipple on the crackcase tube to the flowcontrol valve... I hooked the fuel tank vent tube to the flowcontrol valve.. and I used a small filter on the last remaining nipple on the FCV...

 

My PVC hose is routed normally... lol..to triple Webers...

I hooked the TOP valve cover vent to a check-valve, then a metal tube to an exhaust venturi welded into the collector...

 

Low speed:

At idle, cruise, or decel the PVC valve draws fumes into the intake... the exhaust venturi is only somewhat effective at idle(but not zero)

 

High speed:

At wide open throttle(WOT) the exhaust venturi draws a fairly steady low vac(with high volume) under a wide range of RPMs(with a freeflow exhaust system) The PCV valve stops functioning under low intake vac conditions...

 

Under all conditions:

The small nipple on the large crankcase vent tube runs to the flow control valve(FCV) port... The flow control valve will bleed air into the crankcase from 2 ports... the tank port opens and pretty much stays open under all conditions(both ways)... the second port originally ran to the aircleaner.. this opens to atmosphere in order to break high crankcase vacuum and allow tank ventillation..

 

The engine pulls a strong vac under a variety of conditions...

I have low oil consumption...

a positively vented tank(less fumes)..

a clean engine(even with the normally weapy metal headgasket)

and decent vac with an aggressive cam and triple DCOE 45 152 on a TWM manifold....

 

vrmm VROOOOOMMMM.....

 

WeberCAIrear.jpg

 

airbox.jpg

 

bafflerear.jpg

 

bafflefront.jpg

 

...

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Guest TeamNissan

I love the sweated copper line lol, no sarcasm intended lol.

 

I use the "flow control valve"(FCV) as a vacume breaker for my superduper crankcase vent system...

 

I have Hooked the small nipple on the crackcase tube to the flowcontrol valve... I hooked the fuel tank vent tube to the flowcontrol valve.. and I used a small filter on the last remaining nipple on the FCV...

 

My PVC hose is routed normally... lol..to triple Webers...

I hooked the TOP valve cover vent to a check-valve, then a metal tube to an exhaust venturi welded into the collector...

 

Low speed:

At idle, cruise, or decel the PVC valve draws fumes into the intake... the exhaust venturi is only somewhat effective at idle(but not zero)

 

High speed:

At wide open throttle(WOT) the exhaust venturi draws a fairly steady low vac(with high volume) under a wide range of RPMs(with a freeflow exhaust system) The PCV valve stops functioning under low intake vac conditions...

 

Under all conditions:

The small nipple on the large crankcase vent tube runs to the flow control valve(FCV) port... The flow control valve will bleed air into the crankcase from 2 ports... the tank port opens and pretty much stays open under all conditions(both ways)... the second port originally ran to the aircleaner.. this opens to atmosphere in order to break high crankcase vacuum and allow tank ventillation..

 

The engine pulls a strong vac under a variety of conditions...

I have low oil consumption...

a positively vented tank(less fumes)..

a clean engine(even with the normally weapy metal headgasket)

and decent vac with an aggressive cam and triple DCOE 45 152 on a TWM manifold....

 

vrmm VROOOOOMMMM.....

 

WeberCAIrear.jpg

 

airbox.jpg

 

bafflerear.jpg

 

bafflefront.jpg

 

...

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if i were to cap the crankcase vent would that be a bad thing? could it hurt the egnine eventually? if so should i screen it somehow? or would jsut capping it be okay? thanx guys, how about just putting a straight tee with all three connected and let the vacuum needs handle themselves? could that harm either the tank or the crankcase in some way? with foreign fumes?

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Guest TeamNissan
if i were to cap the crankcase vent would that be a bad thing? could it hurt the egnine eventually? if so should i screen it somehow? or would jsut capping it be okay? thanx guys, how about just putting a straight tee with all three connected and let the vacuum needs handle themselves? could that harm either the tank or the crankcase in some way? with foreign fumes?

 

The crankcase NEEDS a vent lol. I would just run it to the intake.

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if i were to cap the crankcase vent would that be a bad thing? could it hurt the egnine eventually? if so should i screen it somehow? or would jsut capping it be okay? thanx guys, how about just putting a straight tee with all three connected and let the vacuum needs handle themselves? could that harm either the tank or the crankcase in some way? with foreign fumes?

You can run it to a catch can if you don't want to run it back to the intake, but it HAS to have a vent, otherwise you'll pressurize the crankcase and leak oil from every seal in the engine. This happens immediately, not over a period of time.

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The crankcase NEEDS a vent lol. I would just run it to the intake.

 

Just running it to the intake is a bad idea... You need the variable flow restriction properties of the PCV valve... Run the bottom crankcase vent tube to the factory PCV valve(just like stock)...

 

The top vent can be vented to a catch can(originally it went to the aircleaner)... I originally stuck a breather filter on my top vent.. It made a mess... my metal headgasket also seeped oil badly...

 

This complete evac system eliminated blowby-gas contamination in my intake(under power)... The engine always gets a clean-unadulterated supply of fresh air through the cabys when I stomp it to the floor... There is no blow-by contamination of my mixture from the PCV valve or the top vent dumping into the aircleaner...

 

I also insulated all the fuel lines, I also used a return line to avoid dead ending the fuel flow... this keeps a constant supply of cool fuel to the float bowls...

 

constant unrelenting vacume on the crankcase from the top and bottom vents has eliminated my engine mess... and ensured the best possible and cleanest F/A mixture...

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I must say... something that has not been addressed in this thread...

 

All of the manuals available for the S-30 cars contain all of the emissions diagrams and routing... they also have a cut away veiw of the FCV... and a full explanation of how the system and it's individual parts operate... You should hook everything up as it was designed...

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The cleanest pic I have is with the engine out. This thing sits just below the coil. That bottom nipple goes to the small nipple Y'd off the crankcase vent. The top one went I believe to the back of the stock air cleaner. But since I switched to the dual webers some 15 years ago that is coming from memory.

 

vent_switch.jpg

 

thats where it goes. but what is it for?

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I must say... something that has not been addressed in this thread...

 

All of the manuals available for the S-30 cars contain all of the emissions diagrams and routing... they also have a cut away veiw of the FCV... and a full explanation of how the system and it's individual parts operate... You should hook everything up as it was designed...

 

Ive got the Factory Service Manual for my 74 260Z, but honestly Nissan has come a long way over the years in writing service manuals. This one is really hard to locate information, the diagrams arent nearly as detailed, and I couldnt find a very clear diagram of the PCV system that mentioned the fuel vent.

 

Oh well... thats what you guys are for, right? :)

 

 

- Greg -

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Guest TeamNissan
Ive got the Factory Service Manual for my 74 260Z, but honestly Nissan has come a long way over the years in writing service manuals. This one is really hard to locate information, the diagrams arent nearly as detailed, and I couldnt find a very clear diagram of the PCV system that mentioned the fuel vent.

 

Oh well... thats what you guys are for, right? :)

 

 

- Greg -

I have the body and engine service manuals and I've found them to be a life saver so far lol.

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