Camshaft running in procedure confusion

Good morning,

My 1974 Commando has reached 102,000 mi.
New +.020’’ oversized lifters have been ordered and a new camshaft as well. I include a copy of the camshaft running procedure provided.(Norvil)



I have 2 main questions that I pointed at by yellow arrows.
Q1: Do they actually ask us to put back the cylinder block + cylinder head (with pushrods of course) to dry test the contact between lifters and cam?
Q2: What are they meaning? : Norton cylinder blocks radially out of position..? What is the cure if so?

Frankly I’m confused about those precautions. I need your lights.

Thank you.

Interesting! Sounds like the procedure per the cam company IF the the lifters aren't making full contact with the cam is essentially..."too bad, you are S O L." They don't indicate there are any options other than a new cylinder block.

FWIW, I never heard of such a test with other engines. New lifters have a convex mating surface to ensure they bed properly with a camshaft. Don't see why this concern exists - the new (at the time) factory cam/lifters wore-in just fine. So what's the difference? Only thing I can think of is a poorly designed lifter or camshaft...

Sergio said:

Good morning,

My 1974 Commando has reached 102,000 mi.
New +.020’’ oversized lifters have been ordered and a new camshaft as well. I include a copy of the camshaft running procedure provided.(Norvil)

I have 2 main questions that I pointed at by yellow arrows.
Q1: Do they actually ask us to put back the cylinder block + cylinder head (with pushrods of course) to dry test the contact between lifters and cam?
Q2: What are they meaning? : Norton cylinder blocks radially out of position..? What is the cure if so?

Frankly I’m confused about those precautions. I need your lights.

Thank you.

Click to expand...

I believe they mean to use Dykem blue to be on the cam, then with the cylinder and lifters in you will see if the lobes are getting full contact with the lifers. I have seen that OEM the cam lobes do not make full contact, So it is best to check it with just the cam in bolted together engine cases and just the lifters in the cylinder. I suppose you could use a magic marker or a light coat of grease to coat the lobes to show the alignment of the lobes to the lifters. Or you could do some measurements to get a feel for what is going on.. Carl H.

'Micrometer Blue' is known to most of us and 'Engineers Blue' Dykem may well be a trade name, never heard it called that. It is simply a dye you put on metal parts for marking out ( coat a surface in it and make scribe marks as required for the part you are making, and you will be able to see them easily 'in negative' as the Blue is removed by the scribe.

Or it can be used for checking surface contact as in the case you are looking at, i.e. you put it on one part and check it is evenly transferred to the other when assembled and rotated. Carl is right to suggest that even if you do this test you may not see 200 contact between the tappet and the lobe, the contact track may reduce in width around the cam lobe, this can sometimes be seen in the wear patterns, most of us can ignore it as long as contact does not stop at some point because if it is the tappet is being held away from the cam! I have only seen this happen when the tappets are too tight in the tunnels or against the retainers (ref the fettling I mention later to correct this condition). But you don't need to do any trial assembly beyond tappets and barrels to confirm correct fit here, just make sure the tappets free fall to the point they are stopped by the retainers.

102,000 miles, quite something, but, what you haven't said is:

Is the motor now stripped and inspected?

Did the motor cover all of those miles with no impact between cam and tunnels etc? If so why suspect a problem now?

Is the cam you are fitting to the same spec as the one you are removing? If it will be a standard cam, why suspect a problem?

(Of course if it is high lift it is your responsibility to make sure there is no impact now, and if it is say a PW3 or 4S, or similar, expect a problem. You will need to create clearance at the mouth of the tappet tunnels through grinding. But this is nothing to do with the barrels meeting spec, it is due to modification from standard spec.)

Are you having the barrels rebored and fitting new pistons? Does the measured wear actually demand that? If not done yet, can the borer check the 'radial' position of the bores? Before and after boring!

(As an aside, why does 'radially out of position' sound like bullshit? Particularly without a drawing to indicate which radial we are talking about!! Which surface has been machined wrong?)

Have you confirmed the need for +0.020" tappets/followers through inspection and measurement?

(The last standard size ones I had from AN were actually several thou oversize and might well fit without the fettling I had to do on them to put them into the barrels, there have been discussions on here about that. AN will surely tell you exactly what they are supplying as a standard follower now, check out the discussions!!)

Are you in any way boring the tappet tunnels to suit the new tappets?

Rumour has it that at some point in the past, a certain supplier has allegedly provided customers with barrels that were scrapped by the manufacturer for not meeting spec. Guess which supplier that was? Don't be surprised if it is the one that is telling you that barrels can be out of spec!

Rest assured, again rumour has it, allegedly, whatever happens, in that supplier's opinion, it will be your fault!!

SteveA said:

102,000 miles, quite something, but, what you haven't said is:

Is the motor now stripped and inspected?

Did the motor cover all of those miles with no impact between cam and tunnels etc? If so why suspect a problem now?

Is the cam you are fitting to the same spec as the one you are removing? If it will be a standard cam, why suspect a problem?

(Of course if it is high lift it is your responsibility to make sure there is no impact now, and if it is say a PW3 or 4S, or similar, expect a problem. You will need to create clearance at the mouth of the tappet tunnels through grinding. But this is nothing to do with the barrels meeting spec, it is due to modification from standard spec.)

Are you having the barrels rebored and fitting new pistons? Does the measured wear actually demand that? If not done yet, can the borer check the 'radial' position of the bores? Before and after boring! (as an aside, why does that sound like bullshit?)

Have you confirmed the need for +0.020" tappets/followers through inspection and measurement?

(The last standard size ones I had from AN were actually several thou oversize and might well fit without the fettling I had to do on them to put them into the barrels, there have been discussions on here about that. AN will surely tell you exactly what they are supplying as a standard follower now, check out the discussions!!)

Are you in any way boring the tappet tunnels to suit the new tappets?

Rumour has it that at some point in the past, a certain supplier has allegedly provided customers with barrels that were scrapped by the manufacturer for not meeting spec. Guess which supplier that was? Don't be surprised if it is the one that is telling you that barrels can be out of spec!

Rest assured, again rumour has it, allegedly, whatever happens, in that supplier's opinion, it will be your fault!!

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Lots of good points raised.

If by Norvil you mean Fair Spares Led Emery then be aware that 15 years ago both Dynodave and myself measured camshafts supplied by him that were poorly machined. The base circles varied in height and the lobes had differences in lobe centres and quietening curves.

In NZ we would call the blue paste machinist blue and you use a very fine smear to determine what parts are touching and what is not. This is good practice but you will need a good workshop engineer and facilities to fit your oversized followers and he can check this. Just put the barrels on. Do not fit the head.

As Steve says do you need oversized followers ?

I also support Steve's advice about checking all clearances in the cases and barrels if you are fitting higher lift cams. Also lateral clearance for the pushrod including the head gasket area.

johnm said:

Lots of good points raised.

If by Norvil you mean Fair Spares Led Emery then be aware that 15 years ago both Dynodave and myself measured camshafts supplied by him that were poorly machined. The base circles varied in height and the lobes had differences in lobe centres and quietening curves.

In NZ we would call the blue paste machinist blue and you use a very fine smear to determine what parts are touching and what is not. This is good practice but you will need a good workshop engineer and facilities to fit your oversized followers and he can check this. Just put the barrels on. Do not fit the head.

As Steve says do you need oversized followers ?

I also support Steve's advice about checking all clearances in the cases and barrels if you are fitting higher lift cams. Also lateral clearance for the pushrod including the head gasket area.

Click to expand...

I edited and added some more stuff...good or bad

johnm said:

....... Also lateral clearance for the pushrod including the head gasket area.

Click to expand...

Yep, had that problem too! Fixed with a burr, but in that case it was real tricky to find, engineers blue on the pushrods and assemble everything!! Part of the issue was non standard steel pushrods in a set of barrels that were probably at the edge of spec and would have been OK with standard pushrods. Initially I found it was the copper head gasket getting marked, but when that was relieved I found it was the pushrod tunnel too!

This is what your want to check and prevent, My MK3 with an aftermarket cam that came with a parts bike. IT was new when installed and after about 8,000 miles , it was toast. I believe it was UK made. This is the second cam that went sour in 17,000 miles.

Advice on keeping it above 2500 for first 30 minutes is important, checking contact area is a simple procedure, just get a tube of engineer's blue. With the cases, cam and block assembled (no crank), you can also peek up through the sump plug to visually confirm lateral contact (and avoid Carl H's scenario)

Camshaft run-in appears to be a series of conflicting techniques. Virtually all builders will tell you to fire up the new engine, let it get just short of hot, about 10 minutes, I'd guess, let it cool, retorque all fasteners, check valve clearances. yada, yada.

Point is that it isn't 20 minutes of 2500+ RPM. I haven't had any issues with stock or slightly more aggressive cams, but is always makes me wonder.

Best.

Just to be clear 20 minutes at 2500 rpm doesn't mean letting the bike just sit there running. No air cooled motor is going to survive that. Maybe with a huge fan, maybe. The advice originates with water cooled car engines which are better able to withstand no airflow. It's still good advice but the best thing to do is get the bike on the road right away and keep the revs up. Also that is the best way to seat rings. I'm sure most of the old hands on here know this already but there may be a newby out there.

Re; the picture of the shot cam & followers - checking the pol pump pressure wouldn't go amiss while the engine is running to check that all is well. Pouring oil down the exhaust tappets cover prior to start up to lube the cam lobes wouldn't either.

Most new cams come with a small cube of cam lube to apply when fitting, well the 2S cam that I brought for my Manxman project bike did, as for running it in just ride the bike like you do to run in any new motor, don't over rev it and never labor the motor, once the oil pump has been primed and kick the bike over without the plugs in till oil is reaching the head and when assembling the motor you should be lubing everything as you put things back together.

Ashley

When I re work my Nortons, I always have resurfaced lifters that are finished nicely, Good cam lube and oil flooded into the head to provide good oil. the bikes are fully primed and brought up to full oil pressure with my priming procedure.

But UK cams used in MK3s and the Combats, to me, are all suspect as to quality and there is cam to lifter alignment problems that need to be checked and solved. My latest project using 73 or 74 850 cases needed some adjustments to align.

I have a early 2S cam that has similar problem that most of my MK3s and my MK2A I've owned.

Last 2 bikes I did were run in for a while with Gibb's Driven zinc break in oil and then changed out to Valvoline VR1 zinc oil at about 100 miles.

The first bad cam from my current MK3... I sent it to Web to be reworked, They said they never saw a cam lobe that was so badly worn ,1/2 of a lobe was worn off. But I told them the lifters had to be surfaced only a few thou to make them right (Oddly) . But this time the pictures show the timing side had 2 bad lobes and 2 lifters that are scrap. .

My Web hardweld cams do not suffer the same fate after many racing miles.

You can destroy a cam in 500 miles or less with improper break in. 2500+ RPM for 20-30 minutes is pretty much a standard cam break-in procedure - start the engine and IMMEDIATELY take it up to that RPM AND KEEP IT THERE for the time period.

How you do it is not important - but the RPM/time is important. IOW, whether you start an engine and, in neutral, run it for the RPM/time necessary or drive/ride the vehicle to do so doesn't matter. The point is to maintain the RPM for the time required, not to vary it. It is NOT the same as "breaking in" an engine. Engine break in is done after cam break in. Obviously the air cooled Norton won't like sitting there in neutral at 2500 RPM for 20-30 minutes so that pretty much means riding it. Unless you do the break in on a track or have the large fan previously mentioned, it most likely means riding means around the neighborhood for 20-30 minutes in 1st gear!

In my experience, the vast majority of cam failures are caused by improper break in. The use of old lifters with a new cam can also rapidly destroy the cam.

Floor fans work well to cool the engine during initial break in

Carl H said:

But UK cams used in MK3s and the Combats, to me, are all suspect as to quality and there is cam to lifter alignment problems that need to be checked and solved. My latest project using 73 or 74 850 cases needed some adjustments to align.

I have a early 2S cam that has similar problem that most of my MK3s and my MK2A I've owned.

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Yes, but I am guessing that any motor that has one of those cams in hasn't just completed 102,000Miles?

Those cams were around over 40 years ago, if you have one it will have been sitting in a low mileage bike just waiting to bite someone.

Not saying you can't have bad cams today, but cam problems I and most others have had since 2015 are not down to these cams, something else is at play!

SteveA said:

Yes, but I am guessing that any motor that has one of those cams in hasn't just completed 102,000Miles?

Those cams were around over 40 years ago, if you have one it will have been sitting in a low mileage bike just waiting to bite someone.

Not saying you can't have bad cams today, but cam problems I and most others have had since 2015 are not down to these cams, something else is at play!

Click to expand...

I never had problems with stock OEM Commando cams pre 1975, it is the others I mentioned . The cam are toast in less than 8,000 miles and probably wearing from day one.

Very few bikes of any brand were broken in by owners using cam break in methods. So I don't use that as a reason in most cases

Oils did change, (older SD oils had better stuff in them) The formulas changed for Cat convertors.

The late 1975 cams with the wide intake lobes were the ones that failed in 4 of my bikes always on the Primary (left) side. There are issues that need some thought and care when assembling an engine for a rebuild. The more I look at things, the more time and thought I put in to solve all issues and make them work on the track and street. Right now I am exploring cam and lifter alignment and checking thing twice to make sure they are not naughty but nice.

Thank you all of you for your comments. Frankly it was very very strange to me, as mentionned in my yellow arrow/question 1, to reassemble the cylinder head to check the contact between camshaft and tappets/lifters. So should I : 1- put some machinist blue on the cam lobes or lifter, 2- reassemble crankcases without crankshaft, 3-put back cylinder barrels, 4-turn the camshaft (with some slight pressure on each lifters???), 5-check that full contact between cam and lifters. The pictures provided by Carl H (thank you Carl) show the extreme opposite of full contact. I understand. Should I understand that Carl's photos show what I asked in my yellow arrow/question 2 about cylinder block radially out of position? If so, I can't see how to align cam and lifters, as they both have fixed position, except may be a small cam end float, that would certainly not compensate for the alignment needed on Carl's photos.

Now, to be more precise about Steve A questions:

Yes, my Norton is over 102,000 miles with the factory installed cam in 1974. The reason of my engine overhaul is that lower compression warned me that 55,000 miles rings set needed some attention. BTW I wanted to check the noisy lifters I could hear especially when starting the engine. After inspection, rings gap showed out of tolerance. Barrels measurements showed no significant wear; the pistons less than .0015''. Total cleareance between barrels and pistons .0065, .007''. So, I have decided to put new pistons and after the cylinder honing, the clearance is .005'' that I consider perfect. Am I right?

No impact observed at the lifter's tunnel as this is a standanrd cam. BTW the new cam (Norvil/Les Emery) ordered is standard too. Is there any measurements to do on the cam? If so what are the specs(the values) to check? The cling-cling heared from lifters area comes from the ovalised worn tunnels in the block. So I ordered .020'' oversized lifters(Andover new old stock) and a machine shop took a whole day of work (not an amateur's task) to achieve a perfect round rebored and honed tunnels with a finished clearance of .002'' between lifters and tunnels.

Another observation/surprise came after opening the crankcases. Both outer race's Superblend dropped right away from the cases!!! No heat applied to the cases, nothing!! Upon inspection, I can't confirm a lot of bearing spinning in the case. May be a little bit, but no big shinning surface in the case. Is this situation common? Also I would fear shimming the crankshaft end float at the outer race end if some spinning occurs and destroy the shims through out the bearing rollers...ouch!!! Am I right?

Again, thank you all of you, to take time to give precious advices from your experience. I'm eager to read you.

Sergio

Sergio

Sergio said:

So, I have decided to put new pistons and after the cylinder honing, the clearance is .005'' that I consider perfect. Am I right?

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Yes

Another observation/surprise came after opening the crankcases. Both outer race's Superblend dropped right away from the cases!!! No heat applied to the cases, nothing!! Upon inspection, I can't confirm a lot of bearing spinning in the case. May be a little bit, but no big shinning surface in the case. Is this situation common?

Must be a function of the mileage, either fit custom rings to the housings say made from bronze or have the OD of the new bearings copper plated so the fit of bearing to housing is a 1.5 thou interference fit. The new bearings would need to be C3 internal clearance.