Rocker spindle to Rocker clearance

Old Bloke · May 16, 2014

I am busy replacing the Inlet Valve seals at the moment, using "the Ludwig" method, which is all going well.

I wonder if anyone has a feeling about acceptable "slop" on the rocker arms, that is clearance between the spindle od and the rocker id? I have heard this cited as one cause of head over-oiling, and thought to check this whilst the rockers are out?

Mines feel a bit sloppy, but that's a bit subjective as I've never seen inside another Norton head.

Peter

Bernhard · May 16, 2014

The rocker spindles should be a sliding fit on the spindles, any more than that, it is worn.

Old Bloke · May 16, 2014

You mean absolutely no play?
If there is play, which is liable to be worn, the Spindle or rocker? Without dimensions, it is hard to say I suppose......

lcrken · May 16, 2014

The factory spec allows .0013 to .0018" of clearance between rocker and shaft. That's enough to allow you to feel a very slight amount of play between them, but only VERY slight. I used to have the spindles hard chromed, which reduced the clearance by a few tenths, and they still rotated freely and worked fine in the race engines.

Ken

Old Bloke · May 16, 2014

Cool, I can check that. When you hard chromed the spindles, did you have to ream the holes in the head to match that?

Hobot · May 16, 2014

What about the rockers shifting against the factory spring spacers laterally?

Old Bloke · May 17, 2014

After removing the Inlet valve springs, I noticed that there were no heat insulating washers fitted. I know that's been covered extensively elsewhere so I will skip that question, however can anyone please tell me the dimension of a heat insulating washer, Diameter, hole diameter and thickness. I am asking as I would like to see what a spacer that size would compact the spring? I'd measure one but I don't have any!

Peter

pete.v · May 17, 2014

Old Bloke said:
After removing the Inlet valve springs, I noticed that there were no heat insulating washers fitted. I know that's been covered extensively elsewhere so I will skip that question, however can anyone please tell me the dimension of a heat insulating washer, Diameter, hole diameter and thickness. I am asking as I would like to see what a spacer that size would compact the spring? I'd measure one but I don't have any!

Peter

OD = 1.115" ID = .745" Thickness = .060" I measured 4 of them and this thickness is the average, give or take .002".

Old Bloke · May 17, 2014

Thanks Pete, much appreciated.

lcrken · May 17, 2014

Old Bloke said:
Cool, I can check that. When you hard chromed the spindles, did you have to ream the holes in the head to match that?

No. It was still easy to remove and install the spindles by heating the head and using the regular extractor tool. I have noticed that on race engines where the spindles have been removed and installed repeatedly, the fit loosens up a bit, even when the correct procedures are followed. I've also found a lot of heads where the spindle fit in the head has become so loose that the spindles can be removed and installed easily without heating the head. I'm not sure if that is from previous owners removing and replacing them without heat, or if the fit just loosens up over time.

Ken

lcrken · May 17, 2014

hobot said:
What about the rockers shifting against the factory spring spacers laterally?

I replace the springs with bronze spacers and shim the rockers to center them on the valve stems. On the other hand, I've done a lot of race and street miles on engines with the stock spring spacers with never a problem. For me this mod falls into the category of changes that seem like a good idea, even if I have never experienced a problem with the item. But not in the "must do" category. I did have one of the stock spring spacers break once, but the two pieces stayed on the spindle, the engine still ran fine, and I only found it when I tore the engine down for routine maintenance.

Ken

Rocker spindle to Rocker clearance

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