1972 Combat Interstate Camshaft

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snowdr

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Hello

I am currently stripping down the engine on my 1972 Combat Interstate, which I have owned from new, to investigate the cause of low oil pressure when hot. The bottom end has never been apart before, so when I split the crankcases yesterday, I was surprised to find that a standard cam was fitted rather than a 2S. All this time, I’ve never understood descriptions of the power characteristics of the 2S cam, and now I know why! I have never ridden another Commando for comparison. The engine is number 2083**, and the ID plate shows a build date of September 72. Did they start fitting the standard cam to Combats, in the wake of all the problems? The cylinder head and the carburettors are standard Combat.

Anyway, the cam runs in the 72 standard scrolled bushes, with the thrust washers both sides of the timing side bush, but they both lack the fragile tags, which reportedly get broken off, but I cannot see any indication of a breakage. So have I got two tags stuck somewhere, or were the thrust washers ever produced without tags? The thrust washers have clearly been spinning against the cases for some time.

I would be grateful for any comments or help that you can give.

Thanks

Ray

1972 Combat Interstate Camshaft

1972 Combat Interstate Camshaft
 
L.A.B. said:
September '72 seems late for a '208'.



The Combat series ended from 211110 and any unsold Combats supposedly had their camshafts changed.
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When they changed the camshafts, did they change the head as well?
Which camshaft did the later RH6 head 750s have?
 
marshg246 said:
When they changed the camshafts, did they change the head as well?
Which camshaft did the later RH6 head 750s have?
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Greg
I had a ‘73 750 with RH6 head and standard camshaft. This was the high compression version….sometimes called combat. It was not a combat.
Serial number will be 220xxx.
As to snowdr with 208xxx Sept 72 as already mentioned it would be late production and likely already detuned at Norton Villiers. My first Norton was 201123 a combat with double S cam built Oct 71. Both ends of the production year.
 
snowdr said:
Hello

I am currently stripping down the engine on my 1972 Combat Interstate, which I have owned from new, to investigate the cause of low oil pressure when hot. The bottom end has never been apart before, so when I split the crankcases yesterday, I was surprised to find that a standard cam was fitted rather than a 2S. All this time, I’ve never understood descriptions of the power characteristics of the 2S cam, and now I know why! I have never ridden another Commando for comparison. The engine is number 2083**, and the ID plate shows a build date of September 72. Did they start fitting the standard cam to Combats, in the wake of all the problems? The cylinder head and the carburettors are standard Combat.

Anyway, the cam runs in the 72 standard scrolled bushes, with the thrust washers both sides of the timing side bush, but they both lack the fragile tags, which reportedly get broken off, but I cannot see any indication of a breakage. So have I got two tags stuck somewhere, or were the thrust washers ever produced without tags? The thrust washers have clearly been spinning against the cases for some time.

I would be grateful for any comments or help that you can give.

Thanks

Ray

View attachment 112705
View attachment 112706
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Normally, there's no thrust washer on the outside. The beveled thrust washer thin side goes towards the tach drive gear. The thrust washer goes between it and the case. I replace the bushing with the MK3 style (06.5428) - one on the outside and one on the inside - they have built-in thrust surfaces. The beveled washed is still used the same.
 
L.A.B. said:
The parts book lists two but under the wrong (bevelled steel washer) part number.
1972 Combat Interstate Camshaft
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Ya, I've seen that. I haven't seen a Combat with two 062601 thrust washers. Also, as far as I can tell, the parts book pictures don't show two. The AN drawings don't. The 062601 sticks into the timing chest and does provide some thrust surface, but once worn down, the sprocket can run against the aluminum. When building Combat engines, I replace the bushing and 062601 with dual bushing setup (065428). Much easier than replacing the standard Combat bushing and since there is then a s[ace between the two bushings, no scrolled/non-scrolled issue.
 
So have I got two tags stuck somewhere, or were the thrust washers ever produced without tags?
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Inspection of the edge of the thrust washer should tell you if it is a ' Tag Broken Off ' one , or was untagged .

If the rims machined for the full circumferance , there wernt no tag . If theres a quarter inch of messed up edge ,
youre Doomed .

Or wanna throw a welding rod through the oilways , perhaps . To see theres NO OBSTRUCTION .
Like you normally do ANYWAY ! .
 
marshg246 said:
Ya, I've seen that. I haven't seen a Combat with two 062601 thrust washers. Also, as far as I can tell, the parts book pictures don't show two. The AN drawings don't.
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But, as he is the original owner if he didn't fit it then it must have been done at the factory.
 
Thanks for the comments. Just to confirm, the bottom end has never been apart before, so it is as it left the factory. It has a combat head marked 'C', the carbs were 932 19/20. It had a copper head gasket fitted originally (which leaked!).

The timing side camshaft bush is scrolled, and there is a flat thrust washer each side (06.2601?) as well as the bevelled thrust washer (06.1086) against the rev counter drive. Replacing the bush with the Mk3 style bushing sounds like good idea, but is it a simple swap? The factory workshop seems to suggest it is difficult, and I do not have any machining or reaming facilities. However, I don't like the idea of the standard flat thrust washers spinning away against the case.

Regarding those flat thrust washers, I've now examined them and there may be evidence that there were originally tags on them. In any case, I will be looking at the passageways for those missing tags very closely.
 
L.A.B. said:
But, as he is the original owner if he didn't fit it then it must have been done at the factory.
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No doubt, but I've done a lot of Combats and it's the first I've heard of with no tab and two of them. I' never opened one where someone had removed the tab or one has broken off either - all have been intact. So, like many Norton things, a mystery.
 
Greg
I rode the cr*p out of my early combat and never needed to go into the engine. Sold it in 1974 with 5000 miles then bought a ‘69 Pontiac Firebird 400…..the need for speed.
 
cording to N.O.C. service notes . BREAK THEM OFF . I think THIS was the Initial Factory Response .
therefore just because they aint there , dont mean that they ever were .

The Odd COMBAT , New , would run to 8.000 . About six times . if that . Then they were run in . in 200 miles !
( yes , well , school kids ) Early 500 kwackers too . ring ding dingle . go about the same . If they stayed on them .

So , a COMBAT build Spec. is Not to be sneezed at . if youre a press on type . And not a towney . Unless you like stop lights . Green is ' GO ' .
 
I’ve just been checking out the camshaft, and it looks reasonable to me, except all the lobes have this strange dark triangular area at the edge, where the followers appear to have not been rubbing. I’ve taken photos, but they are not too clear. It maybe looks like a manufacturing defect. Has anyone got an opinion? Should I be concerned?

Thanks for any help.

1972 Combat Interstate Camshaft

1972 Combat Interstate Camshaft
 
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