cam adjustment

I want to advance my cam about 4 degrees. The engine has the head on and it
is in the frame. Since the cam is under the load of the valve springs, is there any
easy way to pull the chain wheels off and get them back on in their new positions
within the chain and not have the cam move from pressure of the valve springs?

Have mushrooms so they wont screw up much to gain some slack. :-(
Once the chainwheel is off the cam it may well be tough to get it
back on properly aligned.

I have never had an issue with the lobes being under load, it is just a simple matter (ya, right) of keeping track of all 4 marks.

FWIW, There are markings on the cam chain sprockets as well as the crank gear to intermediate gear. The cam sprocket marking is in relationship to the keyway on the cam, as is the crank gear to the crank keyway
.
To get 4 degrees rather than the default 5 degree increments, you will have to do some rational thinking and camshaft woodruff key filing. Are you sure you wouldn't be satisfied with the simple 5 degree advancement? Why 4 degrees?

Anyhow, here is a link to a cam timing information
http://victorylibrary.com/brit/norton-c.htm

Also,
From the Norvil Tech Tips

"To adjust the camshaft timing you will need a dial gauge and a timing disk. Don't attempt it without the proper tools.
Altering Camshaft Timing

Ideally you will replace the camshaft sprocket with a vernier adjustable one. This allows very fine adjustment of the timing by simply turning the camshaft to the correct position and inserting a locking peg into aligning holes in the sprocket and boss.

In the absence of a vernier sprocket, it is possible to alter the timing by filing a step on the camshaft key ...

The camshaft timing can be advanced or retarded in 5 degree steps by remeshing the pinions and sprockets (one tooth on the camshaft sprocket equates to 40 crankshaft degrees and one tooth on the intermediate gear equates to 15 crankshaft degrees).
For example, to make advance the camshaft timing 3 degrees, turn the camshaft sprocket in the chain 1 tooth clockwise and then rotate the intermediate gear 3 teeth anti-clockwise to advance the timing by 5 degrees. Then reduce this to 3 degrees by filing a step on the camshaft key; this will be a small step and remember that 1 degree on the camshaft is 2 degrees on the crankshaft.
Always advance the camshaft beyond the desired position and then retard it by filing a step on the load side of the key so that it is pulled into location by the running engine."

Thanks Pete. Im pretty up to speed on the procedure it was just that Ive never done it with the
head on all buttoned up. No desire to pull the head off. When I put this engine together I had
just finished when I saw Wolfie had a quick change setup for the cam. Too late! Should also
have gone for a vernier at least to get the cam where I wanted if not to keep the vernier in
service after that.
However that was then. I did see you mention, somewhere in the past, a cam chain with a
master link. This would make adjustment in situ somewhat easier.
Do you have a source for one?

Alright, idiot question here
Why do you advance the cam timing. What are the benefits and how do you know if you should or not? I've always wondered about this but been to scared to ask. As Pete v is and others in this thread seem to be the nice folk of the forum I thought I'd dip my toe in the water.
I understand the actual setup etcetera that Pete has outlined above but not the rationale as to how you arrive at the need to do it and why/what the benefits

To add some suspense for nit pickers on sense of cam + ignition degree optimizing worth in a high stung motor had 360 hp rated propane 'carb' from the late great Over The Hil Gang in 406 V8 at builder that's never done weird combo I ordered up, so similar to recoils to me here, he bet me engine wouldn't reach carb limit and was still right by 3rd pull below 360ho after diddling timing and cam 3x's, paid another $250 for 1/2 degree advance of jet boat cam and pulled 266.6 hp and almost as much torque. 423.8 lbft below 2000. Carb went lean ~4600 so if an over rev event hadn't taken its power out I'd only had to file down the 3 finger size fuel needles or slap a 2nd 'carb' on like the jet boaters did for nearly 800 carbon clean hp exhaust the smells like a kitchen stove. Nothing beats trail/error to destruction then back off some next time, just like Burt Munroe. of course may only apply to vapor fuels. btw engine when in ole Blue chevy van which was 2nd craft I never could stand to find out what it topped out at, the 1st being the P!!. Get them flashback memories in while ya can. Exhausts of above were attended to prior or not allowed imprinting scares.

Onder said:

However that was then. I did see you mention, somewhere in the past, a cam chain with a
master link. This would make adjustment in situ somewhat easier.
Do you have a source for one?

Click to expand...

I think I also mentioned the my bike stalled in the driveway because the link came loose, Thank goodness it was only at idle and I only bent 1 valve.

Testing and getting a good setup may be ok for a mastering chain but it is a poor reason to cut corners. I have one on the shelf that i replace with an IWIS. Seem as though unless you end up cutting off the chain you have, you will need to pull the cam nut just the same.

Dkt26 said:

Alright, idiot question here
Why do you advance the cam timing. What are the benefits and how do you know if you should or not? I've always wondered about this but been to scared to ask. As Pete v is and others in this thread seem to be the nice folk of the forum I thought I'd dip my toe in the water.
I understand the actual setup etcetera that Pete has outlined above but not the rationale as to how you arrive at the need to do it and why/what the benefits

Click to expand...

Tthat is a good question. What say you there, Onder?

My issue was that it was appearent that the keyway on my new cam was retarded 10 degrees hence the need for the adjustment.

I have a JS cam installed and below are his instructions. I find that Im not getting the desired .150 lift until 4 degrees past TDC.
Want to try and advance it a bit, check for clash, and see if there is an improvement in running. It may well be a fools errand
but it is winter and I want to try it and see how it goes.

Appreciate all the assistance.

The only reason for the masterlink chain is for easier experimentation. Same with vernier adjusting cam wheel.
Guess Im brain dead today for not thinking of RGM :-(




STAGE 0 CAM TIMING
 
WITH .005” TAPPET CLEARANCE AT TDC THE INTAKE VALVE LIFT SHOULD BE APPROX .150" AND THE EXHAUST VALVE LIFT SHOULD BE APPROX .140" ADJUST YOUR CAM TIMING ACCORDINGLY.

IF BOTH VALVES HAVE THE SAME LIFT AT TDC (APPROX .145”) THAT IS OK BUT YOU WILL LOSE SOME LOW/MIDRANGE PUNCH.

DO NOT ALLOW THE EXHAUST TO HAVE MORE LIFT THAN THE INTAKE AT TDC (see below).

WHATEVER YOU DO – ALWAYS VISUALLY CHECK THE VALVES AT TDC. Looking in through the port; with a tiny flashlight (magnification helps) – you should see that the intake has the same or a few thousands of an inch more lift than the exhaust. THIS IS ASSUMING THAT THE VALVE SEATS ARE LEVEL AS WITH NEW STOCK HEADS.

Vernier cam sprockets are nice for experimenting.

Depending upon how close you carried clearances, do you think you will need to check valve pocket clearance or do you know you have ample room?

This is JS stage 0 which is a BSA Spitfire cam , pretty much just a street cam.
So far it looks like no problem with clearances. Until I actually move the came ahead a bit
and measure the clash clearance I dont know.
Im more concerned with low end than top end. Street bike use. I live in New York State.
Speed limits are painfully low.

Onder said:

I have a JS cam installed and below are his instructions. I find that Im not getting the desired .150 lift until 4 degrees past TDC.
Want to try and advance it a bit, check for clash, and see if there is an improvement in running. It may well be a fools errand
but it is winter and I want to try it and see how it goes.

Click to expand...

OK, I guess I see where you get the 4 degrees.....sort of. But I wouldo the 5 degree natural progression, check the possision/location of the valve in the exhaust port and for interferance.

At the beginning of my JS2 cam situation, I assumed all would be well with the timing at stock setting not knowing or thinking there would be an issue. I could not get past 4500 rpm and was just basically flat. I was screwing with different ignition and carb settings and was pulling my hair out till I gave Jim a jingle. After applying the precribed methodologies, for me having to advance to 10 degrees, it was off to the races.

I choose not to complain about the keyway thing as the performance is all I could hope for. I did not have a core for him when ordering, but was gracious and sold me the cam just the same. I am totally satisfied with the end results and would surely do it again if given the chance.

Don't over think this and be sure to get your TDC DNO. Please forgive me/us if I under assume your abilities.
PS Don't under assume clash and interferance possibllities either. I does not take much of a bump to screw things up.

Clash between valves will not change when advancing or retarding a Norton twin cam. Clash between valves and a piston could be a problem but if you are going by Jim Schmidt's pistons, cam and timing recommendations it should not be an issue.

Onder said:

I have a JS cam installed and below are his instructions. I find that Im not getting the desired .150 lift until 4 degrees past TDC.
Want to try and advance it a bit, check for clash, and see if there is an improvement in running. It may well be a fools errand
but it is winter and I want to try it and see how it goes.

Appreciate all the assistance.

The only reason for the masterlink chain is for easier experimentation. Same with vernier adjusting cam wheel.
Guess Im brain dead today for not thinking of RGM :-(




STAGE 0 CAM TIMING
 
WITH .005” TAPPET CLEARANCE AT TDC THE INTAKE VALVE LIFT SHOULD BE APPROX .150" AND THE EXHAUST VALVE LIFT SHOULD BE APPROX .140" ADJUST YOUR CAM TIMING ACCORDINGLY.

IF BOTH VALVES HAVE THE SAME LIFT AT TDC (APPROX .145”) THAT IS OK BUT YOU WILL LOSE SOME LOW/MIDRANGE PUNCH.

DO NOT ALLOW THE EXHAUST TO HAVE MORE LIFT THAN THE INTAKE AT TDC (see below).

WHATEVER YOU DO – ALWAYS VISUALLY CHECK THE VALVES AT TDC. Looking in through the port; with a tiny flashlight (magnification helps) – you should see that the intake has the same or a few thousands of an inch more lift than the exhaust. THIS IS ASSUMING THAT THE VALVE SEATS ARE LEVEL AS WITH NEW STOCK HEADS.

Click to expand...

You should check the lift of both valves at TDC. Don't just rely on the intake. Tell us what you get. The important thing is that the intake has a little more lift (or at least as much) than the ex at TDC. The only way to find out if the cam grinder is locating the keyway correctly is to get an average from trying several engines or sets of cam sprockets & gears etc. The gears and sprockets are not all manufactured exactly the same to perfection and the cam grinders have to be persuaded with cash to motivate them to change their setup and move the keyway position to a more perfect average location. Its always important to time the cam - 3 or 4 degrees can make a difference you can feel.

When I installed my JS2 cam in the race bike, I used a stepped key to get the correct cam timing as per Jim's instructions, works a treat, then you can run the rest of the original hardware, I also run an IWIS timing chain
Regards Mike

I have only had a very quick look at this thread becasue these days I can only log into the site while I am at work. After Jerry got defrauded by Romanian scammers he banned the whole country - including me - and this is the only location we have managed to get working

I would very strongly recomend NOT to use a vernier on a Norton twin camshaft. I have tried two and both destroyed themselves over a year or so. Unless someone (or you) makes one with a large diamenter (1/4 " harden steel pin?) then the ones comercially available are not up to the job.

On my bike I used the gear juggling method described above and accepted the 1 or two degree error remaining. Actually I have a collection of sprockets and went through them until I found one that matched closely.

It is possible to set up the cam timing with the head on (back off the tappets) but much much easier with the head off.

Plus whenever you buy a new camshaft I recomend measuring all lobes for the full 720 degree with a dial guage on the pushrod. This way you will find any poor grinds plus check your followers are moving correctly and not jamming or hanging up.

John

Yes, Peel's over rev event beat snot out of their pin but Canaga made a harder one which I'll use to play with till settling down to more trustworthy teeth meshing and key filing. I've been flabbergasted enough in other engines just trial and erroring little at a time for sudden unexpected joy I figure RGM venier will make it more a delightful tedioum.

Agree on all of this. I just am not up to pulling head much less the engine just to move the cam wheel.
A vernier wheel would be great but right now Im not willing to pay the cost of one and if I was Id
still worry about problems. But as a tool to get to where you want to be I can see the utility.

Getting a dial indicator on the valves is not easy. Just so little room with the engine in the frame
and so much alloy making it difficult to find a spot to use a magnetic base!

Im going to have at it the fiddly way and Ill report back.

Thanks again to all.

Onder said:

I want to advance my cam about 4 degrees. The engine has the head on and it
is in the frame. Since the cam is under the load of the valve springs, is there any
easy way to pull the chain wheels off and get them back on in their new positions
within the chain and not have the cam move from pressure of the valve springs?

Click to expand...

Can you let me know what you are trying to achieve by advancing the cam timing? I ask because I'm considering the same.

Thanks

illf8ed said:

Onder said:

I want to advance my cam about 4 degrees. The engine has the head on and it
is in the frame. Since the cam is under the load of the valve springs, is there any
easy way to pull the chain wheels off and get them back on in their new positions
within the chain and not have the cam move from pressure of the valve springs?

Click to expand...

Can you let me know what you are trying to achieve by advancing the cam timing? I ask because I'm considering the same.

Thanks

Click to expand...

I think the issue, and particularly for me, was that on earlier JS cams, the key way was cut incorrectly. For myself, I needed to advance it 10 degrees, where as onder's seems, on preliminary inspections, to be about 4 th 5 degrees off.

I do not believe that Onder has any particular agenda other then to attain good functionality.