Combat rocker shaft oiling

motorson · Jul 9, 2014

My rocker shafts came out badly worn on a low mileage Combat. (around 5000 total miles) I got a better set of rockers and shafts out of an RH4 head that I have. On assembly I was carefully checking to make sure the little oil holes from the central oiling point on the head lined up with the slots on the rocker shafts. I found that when I turned the rocker shafts enough to line up with the little rocker shaft locating protrusion on the rocker shaft cover the oil hole was completely blocked.
Combat head oil hole location.

RH4 head oil hole location.

Both heads side by side.

I just took my Dremil tool and carved the hole over to line up properly and began to wonder if any one else has found this problem. I actually found both of my Combat heads to have the same oil hole location.
Dan.

Hobot · Jul 9, 2014

The Commando heads are designed to restrict oil flow d/t higher flow pump fitted so oil holes and shaft slots barely over lap enough to let oil past. The oil drains out of head may not keep up if too much oil flow allowed. Main restriction is along the spindle with its oil paths and head feed installed opposite each other so may not do anything bad with your one in a row modification.

dynodave · Jul 10, 2014

hobot said:
The Commando heads are designed to restrict oil flow d/t higher flow pump fitted
SNIP

Steve
I am extremely skeptical of this. Why would this change be "COMMANDO"... IMO the only flow control change is going from scrolled shafts to plain shafts...when the change started around 1966 in the whole NHT range of that period. What's different between a 68 atlas and a 68 commando?
Could you please provide an authoritative source for this claim. Sounds like an urban legend in the make.
Sloppy machining of the heads should not be rationalized as purposeful.
The existing hole alignment when used with correct/good end plates and properly installed shafts are more than adequate for flow.
Unfortunately a "commando only" forum seems (to me) to treat its NHT (Norton Heavy Twin) roots as irrelevant.

auldblue · Jul 10, 2014

Hello

I'm glad it's you saying that dave I've only did about three heads all 750 and several oil holes have been off the square, I thought it was just me.

Bat head

Hobot · Jul 10, 2014

Yep Dave the scrolled spindles are put in to restrict head oil flow enough the mis match of the end feeds and slots is a non issue but to fit the spindle covers on to seal. Correct me in I'm wrong please so I'll know where to dremal on mine too.

L.A.B. · Jul 10, 2014

dynodave said:
hobot said:

The Commando heads are designed to restrict oil flow d/t higher flow pump fitted
SNIP

Click to expand...

Steve
I am extremely skeptical of this. Why would this change be "COMMANDO"... IMO the only flow control change is going from scrolled shafts to plain shafts...when the change started around 1966 in the whole NHT range of that period. What's different between a 68 atlas and a 68 commando?
Could you please provide an authoritative source for this claim. Sounds like an urban legend in the make.

We must take into account the fact that hobot only thinks in terms of the [Combat :roll:] Commando, I don't think he was suggesting or meant that it was ONLY Commando heads.

Hobot · Jul 10, 2014

Well set me straighter please, is there some reason to alter to 'correct' the varying mis aligning of spindle ends and head oil holes in Combats or lessor models? Reversed spindle fitting before Commandos means all Commando spindles assembled for restricted oil flow as I wrote - though had forgot what year pump speed uprated.

L.A.B. · Jul 10, 2014

If I remember correctly, I chamfered the edges on some of the spindle slots where they were partially covering the feed holes.

baz · Jul 10, 2014

i'm sure i read somewhere that Paul Dunstall went one stage further and restricted the oil feed to the Norton head! ?? ,,,,,,,,,,,baz

auldblue · Jul 10, 2014

baz said:
i'm sure i read somewhere that Paul Dunstall went one stage further and restricted the oil feed to the Norton head! ?? ,,,,,,,,,,,baz

This is what it says in his book.

comnoz · Jul 10, 2014

I don't think I have ever seen an oil hole that lined up with the slot in the spindle. But when you consider the tight clearance between the rocker and shaft you don't need much volume to lube it. If there is a passage .020 in diameter that will supply all the lube needed by the spindle.

What usually wears out the rocker spindles is running dirty oil without and oil filter. Jim

auldblue · Jul 10, 2014

I am not an expert , but the r/spindles I put in I try and get a happy medium and sometimes there is not much of the hole showing , first head I did it kind of panicked me a bit , but in the end I just said bugger it and stuck the head on it's done a few thou now , but hell knows what's happening in there. Everything looks ok when I did the tappets , I pulled them out a bit and had a look . Seemed fine , but what do I know!

J

dynodave · Jul 10, 2014

hobot said:
Yep Dave the scrolled spindles are put in to restrict head oil flow enough the mis match of the end feeds and slots is a non issue but to fit the spindle covers on to seal. Correct me in I'm wrong please so I'll know where to dremal on mine too.

Wrong again Steve
Again Pre Commando...
Scrolled shafts as used on 1949 thru 66 are lubed by the oil returning to the tank. There is extremely low pressure and it is rumored (since I have not measured the hole size in the tank) that there is a restriction to cause a slight pressure to build so "some" oil will get to the scrolled shafts. Scrolled shafts offer very little restriction to flow.

67 and up NHT have a high pressure rocker feed and therfore is dead ended in the flat ground in the rocker shaft. It then leaks lube to the shaft and a bit gets around to the pushrod ball. The flat MUST face away from the rocker ball or is will open the flood gate through the rocker ball.

Every detail may not be exact but this is the general Idea
3 start/6 start/ long rockers/short rockers/ scrolled /plain shafts
I own at least one of every version of these engines 1949-1975

dynodave · Jul 10, 2014

auldblue said:
baz said:

i'm sure i read somewhere that Paul Dunstall went one stage further and restricted the oil feed to the Norton head! ?? ,,,,,,,,,,,baz

Click to expand...

SNIP page 6 of the dunstall booklet

This is what it says in his book.

Click to expand...

Actually there is nothing on page 6 particularly relevant to this subject.
Try page 14 which does refer to banjo bolts with a restricted flow to balance cam lube VS rocker lube. lubed cam is shown on page 17.

IMO...All in all not a big deal...The last year for "easily" doing this mod was 71

Dave
1968 Dunstall Atlas :
http://atlanticgreen.com/dunstall.htm

kerinorton · Jul 10, 2014

this is a new observation for me. in the past I have not looked at this because both my engines don't seem to wear in the valve area, hence not having to adjust my tappets. With that in mind, I presume all is working as it should and so I still go along with the principle [ if it aint broken, don't fix it ]
You seem to be copping it again Steve. Not to worry, its making people think. Keep up the good work.
Dereck

motorson · Jul 10, 2014

Dave, you mention "long rocker" and "short rocker." Are there different length exhaust rockers for Commandos? (Like the Combat vs an RH4 head)
Dan.

auldblue · Jul 10, 2014

dynodave said:
auldblue said:

baz said:

i'm sure i read somewhere that Paul Dunstall went one stage further and restricted the oil feed to the Norton head! ?? ,,,,,,,,,,,baz

Click to expand...

SNIP page 6 of the dunstall booklet

This is what it says in his book.

Click to expand...

Click to expand...

Actually there is nothing on page 6 particularly relevant to this subject.
Try page 14 which does refer to banjo bolts with a restricted flow to balance cam lube VS rocker lube. lubed cam is shown on page 17.

IMO...All in all not a big deal...The last year for "easily" doing this mod was 71

Dave
1968 Dunstall Atlas :

http://atlanticgreen.com/dunstall.htm

Cheers buddy for the heads up but we must be reading different books cos I cannot find the word restricted anywhere on page 14.

By the way you push rod oil seal work a treat.
J

L.A.B. · Jul 10, 2014

motorson said:
Dave, you mention "long rocker" and "short rocker." Are there different length exhaust rockers for Commandos? (Like the Combat vs an RH4 head)

I think perhaps he was referring to the width rather than rocker arm length? As the low-pressure feed rockers are wider.

Torontonian · Jul 10, 2014

The Norton C. head is over-oiled. Restrict oil to rockers. Follow manual.

motorson · Jul 10, 2014

Thanks LAB. I just cut my seats and lapped in the new black diamond valves with bronze guides on my Combat head. All the valves survive a leak test with brake-clean. On installing the exhaust rockers I noticed that they touch down on the edge of the valve rather than the flat surface. I researched this on the forum and found that some recommend shortening the valve and then using a lash cap. I obtained some 5/16 lash caps and did just that. Now the tappet should touch down just shy of the center of the valve. I will post some pictures later.
Dan.

Combat rocker shaft oiling

motorson

Hobot

dynodave

auldblue

Hobot

L.A.B.

Moderator

Hobot

L.A.B.

Moderator

baz

auldblue

comnoz

auldblue

dynodave

dynodave

kerinorton

motorson

auldblue

L.A.B.

Moderator

Torontonian

motorson

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