Braided s/steel for valve-cover breather hose

[Shane]

Hi All,

I've seem some photos of bikes that use a small-diameter stainless-steel
braided hose for the valve-cover breather lines on older round-head
and square-head big blocks. I guess the size is AN-3, much like a
brake hose. Would be nice if the braid was coated, like the Fentubo
brake lines (otherwise it scratches everything).

I've not been able to find the parts to make this fit on my round head.
Has anyone done this and can give a source for parts?

Thanks - Shane.

 

[john zibell]

Shane,

Are you sure the line you are talking about isn't the oil supply line? Such as these: http://www.mgcycle.com/product_info.php?products_id=487

The vent lines are 8mm in size. Something like this may work for you: http://www.sfxperformance.com/parts/SPT29398.htm

 

[Shane]

John, thanks for writing.

I already have the braided oil supply lines. I was hoping to find something similar for the vent lines.

I tried the route of DIY braided hose (like the spectre link you gave), but the end connectors and tubing itsself is just way too bulky and hideous. Think of all the hotrods you've seen done on the cheap where the builders wrap fake braided hose around existing rubber hose. Yechh, it looks that bad. :X

The oil-supply lines are neat and inconspicuous, which is what I am trying to achieve, and still allow the valve covers to breath.

Thanks again.

Shane

 

[Penis Rotor]

If you are looking for clean lines why not just ditch them all together? The rocker vent lines were a constant vexation to the engineers over the years, their purpose is to (Supposedly) help preent the forming of mayonaise in the top end in cool conditions. Thing is they don't work.:laugh:

Over the years the V7's didn't have breathers, then with the advent of the 'T' series bikes they got breathers, then with the LeMAns III and T5 they disappeared again and then on the later Tonti LeMans and Calis spigots came back but were for oil return from the frame as much as venting the rockerboxes.

I've pissed off all the vents on my Roundfin top ends as they essentially were useless. If you want to use smaller hose? that's fine. Just get some 8mm banjos with speedflow fittings and make some up, you can get some clear pipe to go over the braid or perhaps there is a clear shrinkwrap. I dunno.

Pete

 

[Daniel Kalal]

pete roper wrote:

Over the years the V7's didn't have breathers, then with the advent of the 'T' series bikes they got breathers, then with the LeMAns III and T5 they disappeared again and then on the later Tonti LeMans and Calis spigots came back

just to add another data point: The California II does not have the valve cover breather/drain hose (even though the Lemans of the same years did)

 

[mtiberio]

the lemans III was the same as all the loop frame bikes with the exception that it used the backbone as the breather box (ok, one other distinction, it had a ball bearing check valve rather than a flapper in the box). Unlike earlier tontis, it had NO hoses running to the valve cover area from the breather box (which made it like the loops).

the lemans IV ditched the return from the backbone/breather box to the oil pan, and had 2 returns from the backbone to the valve cover areas (thru the head actually, not thru the valve cover).

the california IIs had 2 different configurations I believe. early ones had a breather system like lemans IIIs
later cali IIs had a breather system like the lemans IV...

I'm with pete on this one. I cap all valve cover vents (my current ride is a convert drivetrain in a loop frame). I run my bikes fairly hard, and never have mayo under the valve covers (and I run all winter). I also run oil some consider on the thin side.

I have no strong opinion on flapper/check valves, and leave the flapper valves in the breather boxes if so equipped, but tend to remove the ball bearing check valves in bikes so equipped. My belief is if the motor can push oil into the box, why not let it suck it back as well.

 

[Shane]

Guys,

Thanks for the tips. I'm going hoseless.

 

[Morizzi]

mtiberio wrote:

I have no strong opinion on flapper/check valves, and leave the flapper valves in the breather boxes if so equipped, but tend to remove the ball bearing check valves in bikes so equipped. My belief is if the motor can push oil into the box, why not let it suck it back as well.

Good point.

It is my belief that the big block breather system works the wrong way round. The ball valve forces the flow out of the crankcase and then back down the rocker breathers if so fitted. The small block system works the other way round, the same as a Morini.

The hot air with oil mist rises up to the rockers naturally plus assisted by pressure. It is actually designed to assist in valve gear lubrication like a Morini. The oil mist condenses on the inside of the rockers and runs down to a ridge on the inside. This ridge has 2 fangs directly above the rockers and the oil runs down to these fangs and drips off onto them. Next time you remove small block rocker have a look inside. B)

The rocker breathers go to a breather box which has 2 outlets. The lowest one is the sump oil return. This returns beneath the oil level stopping pressure from coming up this hose and assisting in breather direction. The other is the vent. This used to go to the clean, negative pressure area of the filter box. This ensured that any air being sucked into the crankcase caused by the pistons raising at low revs was clean and the negative pressure aided in sucking the air through the breather system. Just one of the disadvantages of pod filters.

The big block system with the ball valve doesn't seem to make any sense to me. It is trying to force air down into the crankcase from the rockers against thermal flow. A bit like trying to push sh*t uphill.

Just my theory on it.

cheers