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Catch Can


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#1 _rorym_

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Posted 11 October 2008 - 02:53 PM

Just noticed after Speed on Tweed I have about 1 litre of oil in the catch can. I revved it pretty high during the last runs and it was over full about 500ml. No strange things happened and oil presuure was always up there where it should be. I am guessing the hi volume pump is just pushing it up to the heads and the extra is running out. Anyone similiar?
R

Edited by rorym, 11 October 2008 - 02:53 PM.


#2 Litre8

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Posted 11 October 2008 - 02:58 PM

Not just the revs and a high volume pump but I think the high corner forces will fill up the outer rocker cover too as the oil flows back up the drain holes.

#3 _rorym_

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Posted 11 October 2008 - 05:56 PM

Pretty much what I was thinking to Howard.
R

#4 _rorym_

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Posted 12 October 2008 - 01:55 PM

Wonder if a thinner oil would solve a bit of the problem?..Maybe its too thick to flow...I am using Edge 25W50. Wonder what VN V8s are supposed to use?
R

#5 _The Baron_

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Posted 12 October 2008 - 02:25 PM

Rory, I am getting some KC rocker covers modified that I hope to pick up tomorrow.

The Kilkenny cast rocker covers have the PVC holes low in the ends of the covers (crap), these I am having welded up. New holes are machined into the top and baffles are welded full length under the covers.

Interested is some pictures?

#6 _rorym_

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Posted 12 October 2008 - 03:08 PM

Please..
R

#7 _waz355_

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Posted 12 October 2008 - 06:41 PM

Hey Rory,

I modified my rocker covers for the same reason. Is one of your outlets for the catch can at the rear of the tappet covers?

I modified mine so they are both at the front. I found that under hard excelleration the rear of the tappet covers fill up with oil and would get quite a bit of oil in the catch can. By just moving the outlet to the front fixed the problem and almost get no oil at all now.

Here is a photo of my set up.

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#8 _rorym_

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Posted 12 October 2008 - 09:04 PM

Std VN ones at the front Waz but the height may play a part.
R

Posted Image

Edited by rorym, 12 October 2008 - 09:10 PM.


#9 ozyozyozy

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Posted 12 October 2008 - 09:07 PM

gday. mine see`s lots of rpm and alot of track work too. after a hard day i get prob half a litre or so. from talking to alot of people, its more of a holden issue. i improved it when i used 25/50 oil and made fittings that attach to the top of the rocker cover and use a hose thats 3/4 inch inside diameter. i also use to large breathers on the catch can eg. 1 1/2 inch sizes. if you have ever seen some old pics of larry perkins engines he had fittings on the inside of the rocker covers.

#10 _82911_

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Posted 12 October 2008 - 09:23 PM

Rory, I can help you out with a set of covers modified with An-12 fittings on the top, not the front or back.
Freshly powder coated in red....
ALTHOUGH, this is how I solved the problem.
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#11 _rorym_

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Posted 12 October 2008 - 09:30 PM

Think I need the breathers on the top like yours Greg and Wazzers...I had to already mod the drivers one to clear the hyd clutch master cylinder.
R

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Edited by rorym, 12 October 2008 - 09:35 PM.


#12 _82911_

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Posted 12 October 2008 - 09:33 PM

Let me know. They are on the shelf.

#13 GML-31

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Posted 12 October 2008 - 10:02 PM

rory those fittings are just on a taper by memory can you point them up instead of down?

#14 micklx

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Posted 12 October 2008 - 10:38 PM

I had this happen but much worse.
At my first outing at Phillip Island in the Commodore I did 3 laps and the oil light came on. The catch tank had like 2 litres in it.
I got some advice from a multi Commodore Cup title winner about how to fix this.
Modified lifters and rocker covers.
Its all in my racecar thread.

Edited by micklx, 12 October 2008 - 10:38 PM.


#15 _waz355_

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Posted 12 October 2008 - 11:04 PM

Aparentley back in the day of the 308 racers this was a very common problem as they supply too much oil to the top end.

A lot of engine builders used to modify the push rods or lifters so they would not flow as much oil to the top end.

I have read they used to braze or solder the holes in the push rods then redrill them smaller.

#16 rodomo

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Posted 12 October 2008 - 11:24 PM

I'm pretty sure I've read here somewhere about drilling the drain holes in the head bigger too.
Long time ago and not an option at the moment I would imagine.

#17 TerrA LX

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Posted 12 October 2008 - 11:36 PM

You can buy push rods with a smaller hole for this reason.

#18 _rorym_

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Posted 13 October 2008 - 07:02 AM

Evident it has mainly come from the passengers side cover...figures...Speed is mainly right hand track.
R

#19 _rorym_

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Posted 13 October 2008 - 01:52 PM

The movement of the breathers to the top of the tappet covers has won out...after looking at all my old race photos from late 70s..early 80s....seems a mandatory mod of the time...plus I will go 10W40 oil. Still want to see those pics Baron.
R

Edited by rorym, 13 October 2008 - 01:53 PM.


#20 enderwigginau

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Posted 13 October 2008 - 02:02 PM

Rory,.
lighter oil is less viscous so will flow more and faster - just keep that in mind.
You need to strike a balance. Once you have moved the breathers, it may not matter anyway.

Grant..

#21 _rorym_

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Posted 13 October 2008 - 03:07 PM

Good point.
R

#22 enderwigginau

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Posted 14 October 2008 - 12:49 PM

I'll clarify more for some of the younguns - once the oil is up top a lighter grade SHOULD drain quicker, BUT under hard cornering/acceleration, it will float about on top more.

Now I don't need to explain when we're asked again later eh Rory?

Grant..

#23 RIM-010

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Posted 14 October 2008 - 01:48 PM

I get it Grant :spoton:

Keeping a bit of an eye on the Circuit threads, I'll be building a circuit car in the next couple of years...

Tim

#24 _The Baron_

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Posted 14 October 2008 - 09:48 PM

I hope this works.

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How's that?

#25 76lxhatch

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Posted 15 October 2008 - 07:22 AM

That looks great! Is there still enough height in the covers to clear a good set of roller rockers? I'd love to know how it works out, would have to be heaps better than the pitiful attempt at baffle plates that come with those sort of covers!




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