Camshaft Conundrum

I am doing pre-assembly checks for end play and clearance on a 20M3S/1511XX engine. Fitting the cam through the timing side bush (with the beveled washer and the "modified" tab washer) and snugging the central nut binds the cam. The cam is marked SS, or possibly 3S (the stamp/etch is poor) the TS has an 06-3020 non-scrolled bush and came with an 06-1086 beveled thrust washer as well as an 06-2601 tab washer with the tab removed; the DS bush is also non-scrolled. The cam is not scrolled. With the cam in the bolted up cases and without the thrust washers the cam rotates freely and has no apparent radial play.

I got the engine completely disassembled, but the PO (the person my client purchased the Norton from) was organized enough to have bagged associated parts. The TS case has an 06-1517 part number the DS is 06-1360, both have a 503 stamped on the inside leading me to believe that they were machined together; the "3" is questionable, it is a very poor stamping on both cases; my eyes aren't much better and the super cutie that works next door isn't around today.

Subtracting the measurement taken from the base circle to the lobe peak and the base circle yields the following: the intakes appear the have an (approximate) .381" lift, the exhausts, .305".

With the beveled thrust washer there is way too much end play, so much that I didn't bother measuring, with the beveled washer and the "modified" tab washer the cam binds.

I'd appreciate any wisdom/suggestions for a solution.

Best

RoadScholar said:

the TS has an 06-3020 non-scrolled bush and came with an 06-1086 beveled thrust washer as well as an 06-2601 tab washer with the tab removed

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RoadScholar said:

With the beveled thrust washer there is way too much end play, so much that I didn't bother measuring, with the beveled washer and the "modified" tab washer the cam binds.

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https://www.accessnorton.com/NortonCommando/camshaft-end-float.10512/#post-143609

LAB, thanks for your response, but it does not offer a solution that I could glean for the end play I can see using the beveled washer only.

Best.

RoadScholar said:

With the beveled thrust washer there is way too much end play, so much that I didn't bother measuring, with the beveled washer and the "modified" tab washer the cam binds.

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It would because the drive sprocket in place pulls the cam to the TS setting the clearance.
(IIRC in the early AM)

RoadScholar said:

TS has an 06-3020 non-scrolled bush

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You are guessing wrong!

RoadScholar said:

20M3S/1511XX

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All NHT since 1949 up to and INCLUDING 20M3S USES thick wall cam bushes

RoadScholar said:

06-2601

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belong in the trash

06-3020 is a thin wall bush, will fit and is used in 200000/300000/325000+ engines

TW pix would be the same with EITHER NMT 2036 thick wall bush OR 06-3020 thinwall bush. In either case only the tapered steel washer is used.

The later bushes will not fit a 20M3S but that matters not.
The T/S bushes are the same width and the camshaft sprocket comes up against the cam shafts stepped shoulder as per the photo I posted.
Install the bevelled washer, tighten the sprocket nut and you will have around 0.012" end float.

With the bevel washer in place the cam will have massive end float until pinned by the sprocket shoulder, the D/S end floats.

https://andover-norton.co.uk/en/sho...-connecting-rods-pistons-camshaft-timing-gear

dynodave said:

TW pix would be the same with EITHER NMT 2036 thick wall bush OR 06-3020 thinwall bush. In either case only the tapered steel washer is used.

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I missed this, yes that is a 850 bush in the pic but as you say no real difference as far as installed width.
I have two 20M3S bushes here marked 06-7538 T/S and 06-7539 D/S on the sealed bags but they must be the older numbers or cross over... checking I see AN use both numbers.

https://andover-norton.co.uk/en/shop-drawing/241/engine-crankcases-crankcase-filter-tachometer-drive

Use the bevel washer only on the inner side for a happy ending.

Edit.
I would add that the 20M3S has smaller oil feed holes to both cam bushes as are the holes in the bushes themselves than the later 850 version.
Should they be drilled slightly larger with a upward bevel/countersink at the entrance might be an option.

The bush oil feed holes are not countersunk on the OD so work very well in cutting a furrow into the case at installation as they did at the factory.
A small bevel to break the edge stops that.

Time Warp said:

I missed this, yes that is a 850 bush in the pic but as you say no real difference as far as installed width.
I have two 20M3S bushes here marked 06-7538 T/S and 06-7539 D/S on the sealed bags but they must be the older numbers or cross over... checking I see AN use both numbers.

https://andover-norton.co.uk/en/shop-drawing/241/engine-crankcases-crankcase-filter-tachometer-drive

Use the bevel washer only on the inner side for a happy ending.

Edit.
I would add that the 20M3S has smaller oil feed holes to both cam bushes as are the holes in the bushes themselves than the later 850 version.
Should they be drilled slightly larger with a upward bevel/countersink at the entrance might be an option.

The bush oil feed holes are not countersunk on the OD so work very well in cutting a furrow into the case at installation as they did at the factory.
A small bevel to break the edge stops that.

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The 20M3S thick wall cam bushes T2036 and T2037 have the oiling distributed by the annular groove so no hole alignment is required like the later thin wall bushes. If there is a burr on the thick wall OD, unless very extreme it would not touch the case. I have never seen this burr defect...
Thin wall bush hole MUST align with the case oiling hole.
remark deleted since it is was not correct

I wrote: TS has an 06-3020 non-scrolled bush

Dynodave responded: You are guessing wrong!

From the Old Britts website:

06-7538 -- NORTON, Bush, Camshaft, Pre 72 R.H. ( $35.75 each). This bushing is only used on Atlas and Commando motors with the tachometer drive on the timing cover.

06-3020 -- NORTON, Bush, Cam, 1973/74 850 R.H. ( $13.20 each). This bushing can be used with any scrolled cam in any crank case with the tachometer drive mounted in the timing side crank case.

Based on what I read on Old Britts I wrote what I thought were facts, as this engine does not drive its' tachometer from a drive mounted on the timing cover. 06-7538 appears to be longer than 06-3020, but I don't have one I can measure.

Again folks believe what is on the internet rather than what is in their face. I often find fault with Fred's advice but I am usually chastised for saying so, when even facts are provided and of course no one bothers to tell him.

06-3020 started with the 200000 engine tach drive style is NOT a consideration
I read you are working on a 20M3S and is what you use to select the bush PN not Freds article

dynodave said:

06-3020 started with the 200000 engine tach drive style is NOT a consideration
I read you are working on a 20M3S and is what you use to select the bush PN not Freds article

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Advice on how to decrease cam end play is what my original question was; I may have provided too much information, but wanted to give as complete a set of facts as I could.

The cam bushes that are in the engine look and feel good; I have no desire to replace them. What threw me was the boxes of engine parts I got from my client included a tab thrust washer (tab removed). I believed that the tab washer came out of a running engine, but now think the guy my client purchased the basket case from either gave him the wrong cam hardware bag or just threw one (tab washer) in; one of the oldest practical jokes mechanics play on each other, not to say mischievousness was his intention. Ironically, I discovered that the same guy sold my son a similar (1973 750) basket case 2 years earlier, with 2 tab washers in the cam hardware bag. When my son and me get started on the '73 we won't be wasting time wrestling with this particular conundrum.

Best.

thick bush, 3 piece combat, thin bush, or 2 piece MKIII dimensionally I have always found them to be reasonably consistant though I would never use the 06-2600/01 system.
The length of all 4 styles of cam bushes are incredibly similar .986-.990". And regardless if early twin chain cam or later 20M3S+ single chain cams, the bare shaft is very close to 1.000"or a little more, so you end up with an adequate clearance. Both cams are mechanically urged to thrust toward the timing side so actual clearance is not a big deal.

I did not want to come back to this now way off topic thread but being an idiot went and checked two 20M3S T/S cases and one 20M3 T/S case along with multiple cam shafts.

All fit perfect with acceptable end float (no binding)
That is the cam shaft, the thrust washer in place, in the engine case, sprocket installed.
THERE IS NO TABBED WASHER.
The beveled washer is a thrust washer that bares against the thrust face of the cam bush flange.

There is around one inch outer face of the beveled washer to the back of the drive sprocket seated on the journal shoulder that the bush rides on.

End float around 0.015".

The end.

Note to self, do not leave Honder parts on bench while working on Norton.

Time Warp said:

I did not want to come back to this now way off topic thread but being an idiot went and checked two 20M3S T/S cases and one 20M3 T/S case along with multiple cam shafts.

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I saw your earlier post before you deleted it, you have my sympathies, no need to beat yourself up; most responses told me what should be there, not how to solve or investigate the issue of excessive cam end play. I did figure it out.

The sprocket had a divot in the key way cut caused by key; I had snugged the fixing nut, not torqued it. I did gently tap the sprocket using a deep socket with the DS case off; the DS of the cam was set on a piece of 2x4, tap, tap, tap. I ended up removing the key, cleaning up the shoulder that the sprocket fits on, cleaned up the keyway cut and cleaned up the sprocket bore until the sprocket and cam, with no key, would completely mate. Putting the cam through the TS bushing with the sprocket properly seated on the cam produced an end play ess than .013, problem solved.

I do appreciate the time that members spent on their responses, thank you; I suspect that I must have asked the wrong question, but take heart, this is a Norton which prevolks the proverbial question: What came first the Norton or the chicken...

Best.

Here is the same cam with a 20M3S bush, the other is a later bush but glad you got it sorted.
Who knows what was going on in 1972 with the tabbed washer as a service part (but have no interest in that year)
The Internet is not always an easy or straightforward communication medium.

20M3S bush on the cam... later bush to the side but can not believe the picture I posted as the first reply did not clearly answer the question.
To solve the problem was posted, push the cam sprocket against the shoulder which had not been done as per the picture.


20M3S bush lower, 850 etc upper showing the OD difference.

Time Warp said:

20M3S bush on the cam... later bush to the side but can not believe the picture I posted as the first reply did not clearly answer the question.
To solve the problem was posted, push the cam sprocket against the shoulder which had not been done as per the picture.

Click to expand...

The picture you posted answered the question of what parts go where and that the tab washer I had was an extraneous wild card. The issue with excessive end play was part my fault for not looking closer sooner, but was, yet, another example of the bigger-hammer-syndrome, which I detailed in my last post.

Your picture gave me a better way to understand the "system" and ultimately lead me to find the problem. Many thanks!

Best.