Increasing oil flow to head

Status
Not open for further replies.
Fast Eddie

Fast Eddie

VIP MEMBER
Joined
Oct 4, 2013
Messages
20,659
Country flag
Following on from an earlier thread, I’ve been looking at the head and rockers again.

As we know, rotating the rocker spindles 180 degrees so the flats line up with the oil feed is all that’s needed to increase flow to the point whereby the inlet guides will be submerged and oil consumption increased.

But... what about the exhaust side? Surely, any excess oil there is just gonna exit down the pushrod tunnels and aid cam / follower lubrication?

Is this right?

If so, it would seem a good way of flushing more cooling oil over the hottest part of the head AND splashing more of it down to the cam.

Another question this would raise is; would there be any negative effect on oil pressure or flow to the bottom end?

As I run Carrillo rods, I already run without the oil holes in the con rods, which should, in theory at least, aid oil pressure.

Thoughts please gents: is rotating the exhaust rocker spindles in order to increase oil flow over the exhaust side of the head a good idea or not??
 
Cam and camfollower lubrication will certainly benefit from inreased flow, but we have to bear in mind that this will be at the expense of oil flow to the bottom end which is not good imo.
 
Peter R said:
Cam and camfollower lubrication will certainly benefit from inreased flow, but we have to bear in mind that this will be at the expense of oil flow to the bottom end which is not good imo.
Click to expand...

That’s my main question Peter. Is this really the case? Or is it simply a case of the OPR valve opening a bit less?

I certainly would not proceed with this idea at the expense of bottom end feed if that is the case.
 
Correct me if I am wrong, but I think that when the oil has gone thru the warm-up cycle, the OPR valve is fully closed.
 
I can’t correct you, cos I don’t know! My gut feel is that you’re right though.

I’m hoping someone out there may have studied this in the past and will chime in with their findings / experience...
 
As long as the OPR valve is open due to excess pressure then feeding extra oil to the rockers works, so maybe find a way to divert the excess oil to the rockers instead of as per the std setup.
 
I think that’s a good idea Kommando, but it’s not the kind of plumbing exercise I wish to embark upon myself.
 
"Gents":rolleyes:

You could fit an oil pressure gauge to the crank feed cavity in the timing cover, get the motor up to operating temperature take pressure reading, then rotate you rocker spindles and check the pressure.
the spindles should rotate with a hot motor.
 
On a B44, with a roller big end so no pressure generated, I removed the OPV and take some of the oil up to the rockers, there is a natural restriction of the rocker shafts so flow is unchanged from std, but the oil is cooler as its straight from the oil tank and not the hot returned oil normally used. I took the OPV valve body, removed the spring and ball,drilled & tapped it 1/8 BSP for a 1/8 BSP quick release fitting and blocked the overflow route to sump.
 
Kommando - you've described what you did to the B44 and the rationale for doing it but not the effect.
What was your assessment of the success, or otherwise, of your experiment?
Cheers
Rob
 
Bike runs well and the top end is quieter than a normal unit single, not pulled it apart to see any effect on part wear but nothing is showing as wrong to need it pulling apart. PES do a similar mod commercially and add an oil filter, no reported issues here either, my B44 cases are too old for that mod.
 
Thanks - sounds like a good idea.
I'm wondering how we might gauge the success of a similar exercise on a Norton heavy twin, Commando included.
 
Esmerela said:
"Gents":rolleyes:

You could fit an oil pressure gauge to the crank feed cavity in the timing cover, get the motor up to operating temperature take pressure reading, then rotate you rocker spindles and check the pressure.
the spindles should rotate with a hot motor.
Click to expand...

Apologies Ma’am!

Indeed, your suggested experiment sounds exactly what’s required. Currently however my steed is already in the early stages of disembowelment, so I’m unable to conduct it myself.

I was rather hoping that some industrious person (gender neutral label) might have already done this, or similar, and could share with us...
 
It's not directly achievable on an engine with shell big ends as I and PES remove the ball and spring.
 
[QUOTE="Fast Eddie, post: 400827, member: 541 Currently however my steed is already in the early stages of disembowelment ...[/QUOTE]

"You mad impetuous fool"

No doubt one of the seasoned track hounds, will have carried out a similar test.
 
Dead simple, you do not have to turn the rocker spindles round 180 degrees, the 3 bolts that secure your oil pipe to the cyl head act as oil restrictors, therefore all you have to do is open up the small hole in each one to increase oil flow, but it beats me why you want to do this, as the oil will as it is direct from the oil pump, be coming out at up to 60PSI when engine is revving along!!!! (assuming you have a 6 start worm on your oil pump)
 
We’re not discussing increasing pressure Bernhard, but flow. And the idea is that increasing the flow of oil will increase the oils cooling of the head.

We know that increasing the flow is easy to do. The question now is simply, can the pump cope, or would doing so starve the crank of pressure or flow to detrimental effect?
 
Eddy :
I feel there is a certain contradiction between your concern about hot oil ( cooler thread ) and your desire to use oil for cooling .
The cylinder head can reach temperatures way higher than the oil can handle .
Even with some extra flow , I believe it will be more a case of the head heating up the oil than vica versa .
Overheating the oil first , and than send it trough a cooler doesn' sound right to me .
Putting burned toast in the freezer isn't going to make it edible .
Personally , I try to restict oil flow to the head to preserve oil pressure .
To improve cooling , you could drill a hole trough the 3 lower fins between the pushrod tunnels to create airflow in that critical area .
Don’t know how to mesure it , but I am pretty sure it removes more calories from the head than that little oil flowing down the pushrod tunnels .
( I also cut the cooling fins 2 mm deeper around the plug and combustion chamber )
Still , I'm affraid we have to live with the fact that our air cooled engines are thermically unstable an adapt our riding accordigly .
If you do want to increase flow , maybe you could drill small holes in the rockers towards the spindle ?
Turning the spindles 180° seems rather drastic ..

Increasing oil flow to head

 
Ludwig,

I’ve already added the “Ludwig hole”. Likewise, I’ve not measured it’s impact, but the logic is sound IMHO.

I don’t see the contradiction to be honest Ludwig. Cooler oil entering the head will create a greater heat differential between the head and the oil, and a greater heat differential would provide greater heat transfer and therefore heat removal.

Increasing the quantity of said oil, would further increase its heat absorbing capacity.

I think the theory is fairly straightforward. In practice however, precisely how much difference it would make I do not know.

Furthermore, it’s all a moot point if there is to be any risk posed to the bottom end!

Another question Ludwig: what’s that other extra hole on the inlet side of your head?
 
Last edited:
Status
Not open for further replies.
Back
Top