richo

pumba

not sure if its a must, but its a big of insurance. it saves an blow-by getting blown into the throttle/carby. i have just had one fitted up to my SS. you be disgusted by the amount of oil that actualy goes thru those things lol

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'55 OVP'... VP SS... 152rwkw unopened 304ci


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pvk308

holden engines are notorious for throwing oil up into the rockers and covers. the oil catch can helps alleviate this by allowing the gas pressure inside the engine to escape or help the engine breathe no they arent a must unless running a big cam with high revs

Smitty2

catch cans on the road are illegal (in Vic) as they do not allow the
vehicle to comply with ADR and EPA regs...and the cops do check.

A sealed catch can is a fire hazard as they fill with oil fumes
..and where do the fumes go? At least a PCV valve re-circulates
the oil fumes back into the inlet manifold...when it least affects
performance


An unsealed or vented catch can is just another receptable (same as your rocker covers)
to hold oil fumes before they are vented to atmosphere ...which is illegal on road cars since
the mid 70s. Vented catch cans are seen on race cars...as they don't need to comply with EPA regs
and and they do provide EXTRA room for engine gases and fumes.

Catch cans on CAMS registered vehicles or vehicles used in CAMS sanctioned events
must be at LEAST 3 litre capacity (on V8 vehicles)



hth

Smitty

Crunchy_NuT

interesting info there - and here i thought I was behind the times with my VY

PRO-GMH

You'll see them alot on turbo cars too. I remember at easternats seeing a certain VL turbo emptying the full can back into the engine... it died shortly after.

richo

if their purpose is to bypass the oil vapour from going back into the carbi, then once caught is obviously no good to return to the motor, if it's no good for reusing then why do the holden plumb their motors to use it again? or is it all just an enviromental emmission crap.

Jimma

I know there are allowances, EPA wise, for cars on straight gas. Can you run a catch can or not?

400HPONLPG

Sure can , all my conversions do ,it all comes down to how the circuit is piped up ,and what were the end objectives for it .

The Can is mounted on the Firewall , 1 feed from each VN rocker cover straight into PCV's then back to can, then to PCV port in carb base , with a 1/8 " restrictor in PCV line . (No restrictor and on a good engine you will lose oil pressure due to the excessive vacuum in sump)

CalaisRider

.
Great info mate, thanks .

.

GTR308

i do it a little different, i run my breather lines from the intake manifold in the valley area. i will tell you why. i look at it like this, you have oil thats trying to drain back in a hurry back down through the drain holes and pushrod holes in the head, meanwhile you have crankcase pressure coming up through the same holes, if you let it breathe from the valley area then it doesent try and come up through the heads allowing the oil to drain back quicker as well as no oil being push out the breathers, as there is plenty of breathing space up through the cam area in a holden. you need to use 2 dash 10 or 12 lines to do it properly, also you want to run the tightest ring gaps and least amount of piston rock that you can get away with for your application to limit blowby.

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308 performance centre, perth

GTR308

how does a big cam effect crankcase pressure?

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308 performance centre, perth

GTR308

on mild engines theres absolutley nothing wrong with using a pcv valve on a streeter, i connected a pcv up on a engine i was dynoing there was absolutley no loss in power

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308 performance centre, perth

400HPONLPG

Ay GTR308 , you are doing exactly what allports does , check out those -12 s on the Lancer engine thread .

GTR308

ok kool i will check it out.

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308 performance centre, perth