Rocker Spindles Too Short

And what do you think holds your valve seats and guides in place , grubscrews??
Speedway, biggest butchers of engines I've ever seen although that is changing as it to is becoming cheque book racing
As you say a remedy for a problem you didn't have is readily available , main point, rocker shaft rotate no oil supply to said rocker shaft unlike what was being posted

Wes and I faced what MexicoMike has, on factory Combat Trixie, we were barely able to suck shafts out w/o shearing threads and about impossible to re install even with about alu melting head heat w/o beating the end apart and once in deep enough almost over damaged the slots trying to get cover tab alignment right.

When Norton switched from 3 start to 6 start oil pump drives in early 750 the oil drains were not adequate so oil built up in rockers to leak through guides to smoke exhaust and mess out side rocker covers so they flipped the spindles to mostly block oil flow to fix. If oil drain could keep up with full flow it would help cool top of head components and hopefully raise bulk oil temps to ideal water boil level.

I opened up the lifter drain notches some and made holes in their bottoms and side plates to assist oil flow down. Intake drain increase would need external tap as done when big bores take out stock path. Exht could be ext tapped too but never heard of it done. This on back of mind for boost blasts extending. Beyond over oiling smoke if oil lingers in head too long its cooks/chokes. Exhaust vac sucker might work w/o more drain area.

What damage did M.M do? Just next time around should work slick as service manual implies? Considering same relief next time in Trixie head.

hobot said:

we were barely able to suck shafts out w/o shearing threads and about impossible to re install even with about alu melting head heat w/o beating the end apart and once in deep enough almost over damaged the slots trying to get cover tab alignment right.

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Hobot your description in Paragraph 1 of your reply is the exact same situation that I was in. I had extreme trouble getting them out even after heating the head to 200deg. When trying to refit them initially with head heated and spindles had been in freezer overnight they would only go in halfway before they jammed solid. Got them back out eventually. I tried to get hold of a reamer that was a couple of thou under the 1/2" bore size required, but alas all I could find was the 1/2" size. Contrary to popular belief by some the spindle is not a sloppy fit in the spindle bore.

Thanks to those who made constructive comments on my situation. The most valuable one being from SteveBorland who suggested I go back to RGM and ask for advice. It didn't actually get to that as I found the solution on RGM's website with a full explanation of modified setup.

Cheers
Don

thunderbolt said:

Hobot your description in Paragraph 1 of your reply is the exact same situation that I was in. I had extreme trouble getting them out even after heating the head to 200deg. When trying to refit them initially with head heated and spindles had been in freezer overnight they would only go in halfway before they jammed solid. Got them back out eventually. I tried to get hold of a reamer that was a couple of thou under the 1/2" bore size required, but alas all I could find was the 1/2" size. Contrary to popular belief by some the spindle is not a sloppy fit in the spindle bore.

Thanks to those who made constructive comments on my situation. The most valuable one being from SteveBorland who suggested I go back to RGM and ask for advice. It didn't actually get to that as I found the solution on RGM's website with a full explanation of modified setup.

Cheers
Don

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I seem to remember from another thread (credit to Comnoz?) that you should only heat one part and freeze another when shrink fitting similar materials. If you do this with dissimilar metals such as aluminium and steel, the heat will be quickly drawn out of the aluminium part by the cold steel part. The steel part does not change a lot dimensionally between hot and cold, but the aluminium part does causing the part to freeze solid. This could have been your problem. Better to heat the aluminium part to specified temperature and the steel part just a little bit to minimise its tendency to draw heat away from the aluminium. Hopefully this tip helps for next time.

Merry Christmas.

I was a newbie back then before this forum existed and basically got told it was my incompetence. If ever need done again I'll send to comnoz for further back up of our extremes hang ups few encounter and how experts deal with it or repair removal/insertion damage. Had to come from factory this way. Seriously I had my late buddy Wesley there who'd done this before also flustered while helping to stabilize head and add torque and hammering while inserting avoiding burning too bad from super heated head. Some lasting Commando memories are ride delights others painful miserable tasks.

So if the slots in the spindle do not align with the drilling coming from the banjo, the path of oil can become blocked? I can understand that. But still don't dig how there could be too much drain oil in the head. Seems like the pathway and supply would be the same as long as the slots aligned with the drilling regardless of the orientation of the flats.

MexicoMike said:

FROM PERSONAL EXPERIENCE - If the spindles are installed in the wrong orientation, you will have too much oil in the rocker boxes which will result in oil pooling in the boxes, above the level of the oil seals because the oil cannot drain from the box as fast as it comes in until it overflows the box.

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Still don't understand why there would suddenly be more oil supplied to the rockers (and draining down) because the spindle flats face one way or the other. I accept that it happens because so many here have learned about it the hard way. It just doesn't make sense unless some other factor is involved. Is the oil actually directed by the location of the flats? Does proper orientation merely spray the oil in the direction of the drain?

Danno said:

Still don't understand why there would suddenly be more oil supplied to the rockers (and draining down) because the spindle flats face one way or the other.

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With the spindle oil holes on the opposite side to the rocker ball-end drillings (so spindle holes/flats facing away from the head) the oil has to pass around the spindle to reach the rocker drilling.
As it's a high pressure rocker feed, without that restriction to flow, (if the spindle holes/flats and rocker drillings were to be lined up) the head would swamp with oil.

L.A.B. said:

With the spindle oil holes on the opposite side to the rocker ball-end drillings (so spindle holes/flats facing away from the head) the oil has to pass around the spindle to reach the rocker drilling.
As it's a high pressure rocker feed, without that restriction to flow, (if the spindle holes/flats and rocker drillings were to be lined up) the head would swamp with oil.

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Ok I guess I wasn't aware of pressurized supply to the ball ends. That makes sense.

Yep, the boxes will definitely fill with oil. I ran the engine with the spindles both ways using a rocker box cover with the top inch removed so I could see into the box with the engine running and I watched the boxes fill, totally submerging the guides/seals. Flip the spindles around - doesn't happen. FWIW, the oil drain holes in the rocker boxes and the drillings through the cylinder are very small diameter - a pipe cleaner is a tight fit - and when replacing cylinder barrels, if you are not careful, you can easily obstruct the oil hole with gasket sealer or just a bit of swarf from a gasket. If there is the slightest obstruction to this very small drain system, the oil will not drain properly even with the spindles properly oriented.

MM. You mention that the head's oil drain hole is small, I agree., I have an engine in pieces on my bench and 'am tempted to drill it out, yet in the 9 years I've been reading this forum I've not read anything about someone doing this. I have seen a few Commando engines with exterior oil drains. Is there any reason NOT to open of the OE drain hole?

Sometimes the valve bottom collar hides the drain hole , by a tiny amount , we used to make a "v" in that collar to offer a better passage for the oil to drain, so if you open that hole it could be more masked than before unless doing that , however if you open in the head , you must go on in the barrel , then in the crank ....

Consensus of decades of experts is there is more than plenty oil for lube purposes with spindles in flow resisting nil smoke position, so main purpose of flow beyond a mere drip is cooling springs. Head can operate fine a good interval w/o any oil flow as long as springs don't heat too much, such as antiques suggestion to pump oil feed at least once every 50 power line posts passed.

So I pulled out a bare Commando head to give it a close inspection. I will guess that the problem area is the intake side. The exhaust has very good drainage to the pushrod tunnel. There is even a 3/16" hole drilled under each valve spring seat to further give good drainage. It needs it because the motor is leaning forward and the oil will pool on the down hill side. The inlet is another story. On a vertical motor like the Atlas, the drainage hole is in a good position at the rear of the valve spring pocket, on the downhill side. However, there is only ONE drain hole when the exhaust has two. Now lean the head forward commando style and the oil has a much better chance of pooling. If anything blocks that hole like a bit of gasket or sealer then the valves will submerge. So when the oil is pumped through the rocker spindle it will flow out more through the Thackeray washer in the center of the head perhaps directing half the flow forewords to the pushrod tunnels.
What I do not understand is the importance of positioning the rocker spindle spit hole away from the center of the head.
Also, I've noticed that when the spindle plates are positioned so the tabs lock into the spindle, then quite often the oil way in the head is partially blocked. Intentional regulation of oil or clumsy engineering?

RoadScholar said:

MM. You mention that the head's oil drain hole is small, I agree., I have an engine in pieces on my bench and 'am tempted to drill it out, yet in the 9 years I've been reading this forum I've not read anything about someone doing this. I have seen a few Commando engines with exterior oil drains. Is there any reason NOT to open of the OE drain hole?

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I had exactly the same thought when I installed new rings/valves/guides/seals a few years back. I considered enlarging the hole but decided not to do that that since as long as the stock hole is clear/clean and the spindles are oriented correctly it will drain the oil properly. Also, and maybe the main reason, I didn't really have any drill that was long enough to do the job in the cylinders and I was a bit concerned about possibly weakening the cylinder in some way. It seemed to me that the factory could have easily made the hole in the cylinders much larger so I thought maybe they didn't for some structural reason. But I'm just speculating; I have no idea re that.

thunderbolt said:

GULP!!!!!!!!!!!!!!

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GULP !

A chainsaw file in drill would work w/o much risk of fracturing a cast iron snagging bowing drill bit stuck in long narrow hole. Properly would take a few series of drills/reamers I'd think. Intake rocker over flow goes down lifter tunnels so that's better area to open drainage if not external intake drain, usually down in front of carb manifold to TS chest.

Another way of course is lowering crankcase pressure. Head oil cooks if lingers long.

The RGM kit was designed to rectify this spindle turning issue and works on my 99 head which had the same problem . The orriginal bolts are now too short though, I bought some 1" stainless camera mount whitworth bolts off e bay and trimmed to length, 3/4" were not long enough (the orriginals are around 1/2") . Your motor may have a different thread form? .

After the Titanic's motor was assembled, I discovered I had left one of the thrust washers off one of the spindles. Funny how one comes to recognize random parts after a while, but I knew what it was as soon as I saw it on the bench next to the engine. I pulled the covers and found the shaft with the missing washer. Then I heated the bosses at both ends of the shaft bore with a propane torch, pulled the shaft out far enough to insert the washer and tapped the shaft back in after applying a little more heat. Never had a problem pulling and reinserting rocker shafts on Norton heads. I always assembled according to the manual, and now I know why one should.