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Discussion Starter · #1 ·
I have a 26 T that has a 1975 Datsun L20B engine.It has a 1" breather pipe coming from the crankcase and an open air breather on the valve cover.So Its like an old car without any pollution controls. I'm tired of the fumes so I would like to at least install a PCV valve.I'm not sure where goes what. I think a hose should go from the crankcase breather to the big vacumn port on the bottom of the carb (holley 4 barrel)and the PVC valve should be in that hose then another hose from the valve cover to the air cleaner .Is that correct? I would appreciate any advice on this subject.
thanks
Gary
 

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You have the right idea for your pvc and breather routing.I am running a 350 chevy in my 48 chevy that I am building and I am going to run the pvc pipe from the right valve cover to the closest vacuum port on the carb and/or intake manifold.The left valve cover will have a breather pipe running to the air breather.I hope that this cures your fume problem. Chevy Mikee
 

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You need to plug your crankcase vent pipe and vent out the passenger side valve cover through a pcv valve to the port under your carb on your intake. The drivers side valve cover needs a breather on it.
 

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Ok First off it's PCV Isnt it ? Positive Crank Case ventilation ? PVC I think is plastic Pipe !
But hey I have my dyslexic moment's Too .
Can tell ya how we do it on Vw engine's . We use a Breather Box . On Vw's typically a vent Hose runn's from a small breather box too air cleaner , then a drip tube runn's straight down, from breather box .
Now what we do is remove breather box /drip tube assembly . Close it off with, a sealed Oil Filler cap, spout that has a 1/2 inch hose nipple screwed intoo the side of it .
The hose nipple, is oil recovery line . Then we drill Both Valve covers , for 1/2 in Hose nipples . ( in Your case 1 Valve cover )
But in Short 2 Line's runn from the Valve covers up too the Beather Box .
breather Box has 3 Hoses commin out of it . 2 from the Valve covers , then the 3rd one runn's back down intoo oil filler spout as a recovery .
The breather Box itself , is typically sqaure , about 5 inches by 2 1/2 in wide 3 inches deep . Has a Baffle plate in top , then Styrofoam breather filter on top of the baffle plate .
These are fairly cheap sett up's sold by Empi , and Bug Pack . Simple .
Does have it's draw Back's . Gett's oily , has too be wiped down , regularly .
But there cool lookin Polished aluminum . Eliminates the drip tube ?
As too installin PCV valve . Vw's also have a system for this ? But I know of no one that runn's one .
But thought I would bring it up . Breather Box System runn's like 20 Buck's , or less .
Much simpler than trying too port a manifold etc. for PCV valve ?
What year is the Datsun Motor ? I Have Bunch of Old Smogg Book's . A Coupla Big Book Chilton's on Older Japp Car's and Truck's .
Could look up Closest year motor, that rann a PCV . See where and how it was ported intoo the Intake ?
But Im thinkin A Oil recovery Breather Box . << Be the Simplest way. Block All the Smogg Port's and Holes off, with Fabricated plates ? 20 buck's at your local Vw Shop
20 Minute's too hook it up ? You will need a Uni Bit , Screw driver , Coupla Feet of Hose and a screw driver ? Or just make one out of a steel cannister ?

Sean
 

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Discussion Starter · #7 ·
Pcv

The engine is a 76 L20B out of a 620 pickup,or out of a 79 200sx,I,m not sure,but they run the same motor. This engine has no smog stuff left on it ,It has a header, and an offenhauser intake.the valve cover has a sealed oil filler cap and another baffeled hole that has a piece of hose screwed into it and running down to the bottom of the block & out into the open air.Then it has a pipe that comes out near the bottom of the block which originates from the crankcase,it is about 1" in

diameter or maybe a little larger,It too just vents into the open air.These are the two things I want to route so I don't get fumes.(let all the fumes go out the tailpipe)
thanks
Gary
 

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So I take it theres no place where it had a PCV valve in it originally ?

I would definately try too figure out how the Crank case was Originally Vented on that year model motor .

But at the Same time Im thinkin a Vw style breather Box . Probably would work out for you . <<, There simple , Easy too install, cheap .

Im goofin off Today will have Look in my Manual's See what it had Originally ? Gett back too you in few Hour's .

Sean
 

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Discussion Starter · #9 ·
They list a PCV valve for it in parts stores.There i a hole with a pipe plug in it on my intake where the PCV valve could possibly go,also there is a place on the base of the carb. When I got this engine it had 2 sidedrafts which were strictly competition and there was no place on the carbs or intake for anything.
 

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PVC%breather routeing

Yeah my 2 book's covering it 1980's Clymer and big book Chilton's 1973 thru 1979. show that the Pcv , valve plug's in right under the Carb intoo the manifold . << Might be the rubber grommett is Missin ? That PCV valve plugg's intoo ? But needs too be Sealed .

Then the hose from PCV, valve Runns down the side of the Block under the , intake manifold intoo A oil seperator block . << Also say's >> Steel net,,<< Probably a closed breather box , with a steel nett baffle , or filter ? << as in your's maybe Missing ? Or Part of it Missing.
? But Hose Goes from PCV valve straight intoo it some how it connect's too this breather box/ AKA oil seperator box , on side of the crank case .

Then Up top It show's the hole in the Valve cover , has hose that goes from Valve cover too a Inline Flame Arestor << Look's too be like an inline 1 way Valve ? But from Valve cover too inline Flame arrestor intoo the Air Cleaner where it is attached too a Filter .

The in Line flame aresstor is probably a 1 Way valve .Made of Flame retardant or Steel . << Too keep A back fireing Carb From Causeing a Crank case Explosion . << as in Probably good Idea too hunt one down . I would think it's needed , Good idea too runn it . Other wise leave the hose unattached from air cleaner , probably ?

Bone yard, it, if it comes up as Obsolete part , at Part's house or the Dealer ?
Hope this help's ?


Sean
 

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Discussion Starter · #11 ·
Thanks a lot!.I dont know if I will need the oil seperator block no iol comes out of the bresther pipe but if u put your hand over it air is coming out of it.I will have to recherch that flame arrestor,never heard of one,but I'll check it out.w When the weather gets better I'm going to go to a U-pull it junkyard thats not too far from me they might still have some of these old cars and trucks (if they haven't crushed them yet) but it's cool because they let you roam around the yard at your leasure,who knows maybe I'll find everything I need,but probably not.
Thanks again
Gary
P.S heres a couple pics
 

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I like that . Cool Car . Yeah I had a Crossley as a Kidd Never got it Road worthy , My Uncle Traded my Dad out of My Car <<, Mean's 2 brothers Convinced me, the young Son/AKA nephew I couldnt Live with out a 350 All Aluminum Block V8 Buick Motor in a Crate . Made By Buick For Sports car's over Sea's ??

But then again I wouldnt really know about that Either Cause All I ever saw of this motor was the Crate it Came in . Due too Some more tradeing went on between my Dad and my Uncle . ETC ETC . << Scandalous :D

But we had Pinto 2000 cc Motor set up in it . << Lighter ETC

On your Weiland Manifold I cant see a Plugg in for the PCV valve <<, It being Aftermarket , Might Not have one .

Best bett Here Im guessin is Check Weiland Manifold Application's <<< see if one came with a PCV Valve and Possibly another Version Your Version with out the Orfice ?

Meaning Im not Sure About drillin an Aftermarket manifold for PCV valve orfice ? But my Book show's the PCV valve pluggin straight intoo the Gas Chamber / AKA Plenum Chamber on the Manifold . Directly under the Carb .

Either that or Back too Vw style breather Box IDEa ?

As too the Oil Seperator Or Closed PCV Breather Box on side of the block <<, Just a Breather Box Stuffed with steel netting Im assumeing ? Lil Round Pipe with Steel Nett in it or a Baffle ?

As too the 1 Way Spark Arrestor Valve <<< This most likely a small round steel valve . <<, What it Doe's is If Carb Popp's back <<, Prevent's the Flash Etc From Goin intoo the top of the valve cover where it Could Possibly sett Of Crank Case explosion .

Not sure if your Famaliar , with crank case explosion's . But Im first cousin's with Jethro ??? Ive Runn few Motor's with this kinda action goin on ? Lott's of Funn !

But Good Luck Cool Car .

Sean
 

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Discussion Starter · #13 · (Edited)
The manifold has 3 plugs,2 of them go into cooling chamber the other one goes directly into the air/gas chamber under the carb,I guess thats where the PCV valve wood go.Now I'm wondering how it would be if I hooked up the crankcase vent to the intake with a PCV valve in it and instead of running a hose from the valve cover to the air cleaner what if I just had a breather on the valve cover? I'm wondering if the suction that the intake would be pulling from the crankcase would cause the breather on the valve cover to pull fresh air in instead of fumes out?(it would also look nicer with a chrome breather than a hose).I'm not sure just what the PVC valve does,does it open and close at certain times or what? If it closes then I guess my valve cover breather idea is out,Oh well I guess (with help) I'll figure it out someday.LOL
Gary
Oh and by the way that crankcase breather pipe is at least 1" round I'll probably have to reduce it down somehow,unless the PCV valve is that big
 
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