Imminent Catastrophe?

[Mick D]

Hi

I see you're from sunny Florida - are you using oil with a suitable viscosity for your location? too 'light' an oil will reduce the cushioning on all surfaces, (especially the hotter running ones), and increased noise.

Regards Mick

[Pharisee]

As I mentioned, it's not the carb slide, (new carb with duct to remote, oem filter), or camshaft end float,(just shimmed them as they were clacking, not the same rattle I'm hearing now), don't think it's tappets as adjusting them makes no difference.

Steve

How do you measure the end float on the camshafts? I guess that the camshaft that drives the magneto (exhaust on my M18) isn't too difficult as you would be able to feel it by pulling / pushing on the sprocket. The other camshaft is not accessible when installed so how is the end float measured on that?
John

[Janet]

on riding I can hear a rattle just as the revs build and it's gear change time.

I know nothing but if everyone is allowed to try putting on the glass slipper/pulling the sword from the stone, I'll offer my quess. Well, more an enquiry really. If all other possibilities has been exhausted, could it be valve bounce? I've been told that sounds like a football rattle. Not a rattling football. This post should make Braap realise why he's better off without friendly chat being offered by riders without the specific answer.

I know, I'll get my coat and close the door on my way out.

[SPRIDDLER]

How do you measure the end float on the camshafts? The other camshaft is not accessible when installed so how is the end float measured on that?

You over-shim the 'blind' axle so that the casing will not close up. Measure the gap. Adjust end float either by moving the inner axle bush or by removing shims from the axle to obtain the desired end float.

[Expat]

How do you measure the end float on the camshafts? The other camshaft is not accessible when installed so how is the end float measured on that?

You over-shim the 'blind' axle so that the casing will not close up. Measure the gap. Adjust end float either by moving the inner axle bush or by removing shims from the axle to obtain the desired end float.

Prezactly. Thanks for saving my typing digit SPRIDS.

Mine doesn't have a mag but float of the inlet cam operating the cb points can be measured as you describe Pharisee. Float could be seen with the cover off as the cam lifted and rotated the tappet. While in there, replaced the ex cam oilseal too.

All knowledge garnered from this place of wisdom.

Thanks Janet, hadn't considered that one.

Mick, yes I settled on Valvoline VR 50 racing oil apparently formulated for big old V8 pushrod engines with lots of zinc and other yummy stuff in it. 20/50 bike oil in the chaincase and 75/90 gear oil I think in the ‘transmission'.

I'll see about doing a Hero video of sights and sounds if I can work out how to post it here. Any advice?

Thanks again All

Steve


Edited to add if I'm thinking right, when the engine is built up, the inner bush can't be moved out to reduce end float, so shims are the only answer.

[clive]

Another possibility as well as valve bounce suggested by Janet is that the hairpin valve springs are rocking as they operate. I have had this problem with the spring lifting at higher revs, it then taps on the underside of the rockerbox cover before settling back down, each time the valve opens. If this is the problem there will be witness marks on the inside of the rockerbox cover. I think old stock springs made for the first models with hairsprings had slightly shorter tangs. These fitted into drilled holes in the seat for the valve spring part number 010017 (see 1949 parts list) this required a special c tool to extract and was a fairly lengthy process. By 52 the seat for the valve spring had changed to an open tray 018275 and the part numbers for the springs had changed as well, I believe because the tangs were longer. Even the illustrations in the parts list appears to show longer tangs. The later system allowed the springs to be installed, again with a special tool, in one movement. My experience was I could fit the spring without the tool. I sorted it by fitting the early trays as I had those but not the later springs.

[SPRIDDLER]

Edited to add if I'm thinking right, when the engine is built up, the inner bush can't be moved out to reduce end float, so shims are the only answer.

Correct, the bush must be a tight fit in the c/case half or it would/could move and change the end float.
I suppose one could try making up a sort of impact puller by expanding a Rawlbolt inside the bush and tapping/pulling it outwards but the expanded Rawlbolt would probably mark/score the inside of the bush. There's very little clearance between the inner end of the bush and the flywheel so probably not enough to use a 'hooked' probe to insert through the bush and ease the bush out. Either way it would loosen the grip of the bush and lead to it moving at some point.
As you said, shims are the easiest and most practical way to go.

[Pharisee]

Does anyone know if shims are available? I've checked the AMOC Spares and the two numbers I have (016847 and 016848) don't bring up any results.

[Expat]

Does anyone know if shims are available? I've checked the AMOC Spares and the two numbers I have (016847 and 016848) don't bring up any results.

Got some from AMC Classic Spares in a range of thicknesses.

Steve

[Braaap]

Sprid with a good tip re cam shimming. We should never stop learning!
Relevant or not.... all knowledge is a step forward.

All suggestions are good i would say Janet?
The poster may be no further ahead... but at least they feel they have company ☺

Two heads are better than one