PW3 Camshaft

If I was to fit a PW3 camshaft to my MK2 850 would I need to change the cam followers or have them reground with a different radius than flat?

Thanks
Don

jseng1 said:

The lobe centers on the PW3 cam are too wide at 107 degrees. Other race cams have closer lobe centers and run better at around 104. For comparison - a stock Commando cam is around 101 or 102. There are no valve clash problems with the PW3 and there is no reason for the lobe centers to be so wide. For instance - the Axtell #3 could be had with lobe centers anywhere from 102 to 105. 102 being the hottest but requiring custom machined valve clash clearance. 105 being intended for street bikes. 104 was the most popular for racers who wanted a drop in cam.

It would be easy to make the PW3 cam with closer lobe centers. PW3 lovers would get better performance. The problem is that you're still stuck with those high wear, HP robbing, heat producing, obscenely heavy flat lunks of iron - Norton lifters. The longer lasting cam setup for lightweight BSA type radiused lifters is a much better idea.

Click to expand...

peter-williams-pw3-cam-t7593.html

You should read this thread too - cams-t12813.html

thunderbolt said:

If I was to fit a PW3 camshaft to my MK2 850 would I need to change the cam followers or have them reground with a different radius than flat?

Thanks
Don

Click to expand...

No.

It is recommended that the old followers are reground flat when fitting a new cam, otherwise they can wear out pretty quickly..... at least that's what cam manufacturers say.

thunderbolt said:

If I was to fit a PW3 camshaft to my MK2 850 would I need to change the cam followers or have them reground with a different radius than flat?

Thanks
Don

Click to expand...

I had to open up the cam tunnel very slightly when fitting mine (a standard issue so do test assemble your engine) it is good practice to reface or fit new followers to any cam just as it is to then keep the followers with the lobe they have run on if removed in future. Also check barrel to cam lobe clearance and that followers to be used will raise high enough and freely in the barrel. All these are normal points when fitting higher lift cam but worth mentioning i thought.
The obvious point is if you have spent good money on a cam why try to save it on followers that could then ruin the cam. So what it the condition of your followers an could you post some pictures.

thunderbolt said:

If I was to fit a PW3 camshaft to my MK2 850 would I need to change the cam followers or have them reground with a different radius than flat?

Thanks
Don

Click to expand...

You need standard flat followers for a PW3. Even if your followers are good low mileage items they need refacing, or they will wear the cam prematurely.

Fitting new AN parts is the right answer, but you will need to hand finish them, and fit them to the specific tunnels they will run in and check that the followers and the cam move freely over the full range of movement...reworking the tunnels with a hone is possible but may limit future replacements!

As has already been said, check the followers go far enough up the tunnel at full lift without touching rough casting or jamming, and that they fall freely back down. And make sure the cam lobes don't touch the cases or barrels. Probably you will need to remove metal from the bottom/curved edge of the follower tunnels in the barrels or the cam lobes will hit.

You are also going to need to make sure the valves clear the pistons at full lift and clear each other on overlap.

Of course it goes without saying that everything else, crank, rods, bearings, pistons/bore, rings head, valves, valve seats and guides also need to be in very good condition for a high lift cam to be a worthwhile improvement, and it really would benefit from increased compression, flowed ports and suitable carburation and ignition.

It is all fun, and depending on how and where you ride, you may end up wanting your old, stock cam back! Another good reason to use new followers and keep the old ones with the old cam clearly marked as to which lobe they are for!

toppy said:

thunderbolt said:

If I was to fit a PW3 camshaft to my MK2 850 would I need to change the cam followers or have them reground with a different radius than flat?

Thanks
Don

Click to expand...

I had to open up the cam tunnel very slightly when fitting mine (a standard issue so do test assemble your engine) it is good practice to reface or fit new followers to any cam just as it is to then keep the followers with the lobe they have run on if removed in future. Also check barrel to cam lobe clearance and that followers to be used will raise high enough and freely in the barrel. All these are normal points when fitting higher lift cam but worth mentioning i thought.
The obvious point is if you have spent good money on a cam why try to save it on followers that could then ruin the cam. So what it the condition of your followers an could you post some pictures.

Click to expand...

Hi Toppy,

Here are the pictures.







Thanks
Don

Considering the PW3s reputation, with some, for galling and rapid wear, I would not chance it. The cost and aggravation of having them re-faced is naught compared to replacing a cam!

My earlier 'no' was only in answer to them not needing to be replaced automatically or re-radiused. They should be re-faced according to the cam makers and it seems crazy to risk otherwise IMHO.

They do look good in the pictures but am with Eddie on the point that as they have not run with your new cam (regardless of what type it may be) at the very least you should have them refaced. I also (from my own experience only) agree with what has been said about increasing the compression to get the best out of it. I have no base gasket an the JS 0.003" head gasket to give me 9 to 1 (measured as best i can with oil filling an test building). It has made the 4k and above rev range much stronger.
But of course it all depends on what other mods an settings you have to your bike. Its not just one wonder part an off you go an they all have to work together. I hope you get what your looking for an enjoy the finished product as that's what it's all about.ė

toppy said:

They do look good in the pictures but am with Eddie on the point that as they have not run with your new cam (regardless of what type it may be) at the very least you should have them refaced. I also (from my own experience only) agree with what has been said about increasing the compression to get the best out of it. I have no base gasket an the JS 0.003" head gasket to give me 9 to 1 (measured as best i can with oil filling an test building). It has made the 4k and above rev range much stronger.
But of course it all depends on what other mods an settings you have to your bike. Its not just one wonder part an off you go an they all have to work together. I hope you get what your looking for an enjoy the finished product as that's what it's all about.ė

Click to expand...

I'm not so sure about that. I have standard compression, a standard Fullauto Technologies cylinder head, a VM 34 Mikuni, a PW3 cam and a set of Jim Comstock's conical valve springs. The increase in torque is significant. It really is a very strong motor.

Fullauto said:

toppy said:

They do look good in the pictures but am with Eddie on the point that as they have not run with your new cam (regardless of what type it may be) at the very least you should have them refaced. I also (from my own experience only) agree with what has been said about increasing the compression to get the best out of it. I have no base gasket an the JS 0.003" head gasket to give me 9 to 1 (measured as best i can with oil filling an test building). It has made the 4k and above rev range much stronger.
But of course it all depends on what other mods an settings you have to your bike. Its not just one wonder part an off you go an they all have to work together. I hope you get what your looking for an enjoy the finished product as that's what it's all about.ė

Click to expand...

I'm not so sure about that. I have standard compression, a standard Fullauto Technologies cylinder head, a VM 34 Mikuni, a PW3 cam and a set of Jim Comstock's conical valve springs. The increase in torque is significant. It really is a very strong motor.

Click to expand...

Ken, when you say "The increase in torque is significant" ... at what revs are you referring to? I seem to recall you mainly used, and are perhaps referring to, a lower rev range than Toppy.

He is impressed with his performance gain above 4k. Perhaps you guys are actually agreeing with each other...?

thunderbolt said:

If I was to fit a PW3 camshaft to my MK2 850 would I need to change the cam followers or have them reground with a different radius than flat?

Thanks
Don

Click to expand...

Hi Don,

When you buy a pw3 cam full fitting instructions come with it, or you could give Norman White a phone if you've a mind to and I'm sure he will give you a full run down before you commit to buy.

The followers are ground , tunnels and cases are also modified if need be. It's not expensive to have the work done ,if for whatever reason you don't undertake it your self and it doesn't take that long either.

Hope your new engine gives you what you want.

Jg

Fast Eddie said:

Fullauto said:

toppy said:

They do look good in the pictures but am with Eddie on the point that as they have not run with your new cam (regardless of what type it may be) at the very least you should have them refaced. I also (from my own experience only) agree with what has been said about increasing the compression to get the best out of it. I have no base gasket an the JS 0.003" head gasket to give me 9 to 1 (measured as best i can with oil filling an test building). It has made the 4k and above rev range much stronger.
But of course it all depends on what other mods an settings you have to your bike. Its not just one wonder part an off you go an they all have to work together. I hope you get what your looking for an enjoy the finished product as that's what it's all about.ė

Click to expand...

I'm not so sure about that. I have standard compression, a standard Fullauto Technologies cylinder head, a VM 34 Mikuni, a PW3 cam and a set of Jim Comstock's conical valve springs. The increase in torque is significant. It really is a very strong motor.

Click to expand...

Ken, when you say "The increase in torque is significant" ... at what revs are you referring to? I seem to recall you mainly used, and are perhaps referring to, a lower rev range than Toppy.

He is impressed with his performance gain above 4k. Perhaps you guys are actually agreeing with each other...?

Click to expand...

I'm getting a significant torque increase right off idle. As I've only revved it to 5000 revs in 7000 miles, I am not really that interested in removing bottom end grunt and replacing it in the top end. With 7000 miles up, it still impresses the hell out of me every time I open the throttle. Just going with the flow of traffic and short shifting through the gears is a joy, but when that gap appears, it's just pure go. Top gear performance is great. I run a 22 tooth sprocket and when I had a 23 tooth and a standard motor, it felt a bit breathless, especially getting back to cruising speed after backing off for traffic. Now I feel I could run a 23 tooth with ease. Which, by the way, I fully intend to do. Ben, from British Imports, who built it, is so impressed by it that he rates it above any other Norton he has ridden, even some quite fancied bikes with trick internals. As I've always stated, the beauty and sheer joy of the Norton Commando is it's prodigious low end and mid range and every mod I've made is to accentuate this. Same philosophy with my Fullauto heads. Play to the Norton's strengths. As mine is an all round, everyday bike, I really don't need a strong top end, but, if that's your thing, then go for it.

At 10,000 miles, the engine will be completely stripped to assess the mods made and the effectiveness of the ceramic coating. Results will be posted, warts and all.

Fullauto i have a different set up to you so it will not be the same result. PW3 Hemmings big valve head RS springs an titanium valve collars lightened rockers twin amal premiers and 1 1/2 exhaust (i intend to fit standard size in time as i bought it 18 months before Eddie did his dyno test DOH). The motor was well past its best to say least before a total rebuild (including fitting all of the above) so i can't really compare its performance but Mick Hemmings said increasing the compression would get the best from the cam but as i have an Alton Ekit i left compression standard for fear of damaging it. But it just didn't go as well as i thought it should over 4k. I increased the compression as mentioned before an it proved that Mick was right and if he doesn't know who does. Now it just pulls an shows no real signs of running out of steam but just pulls harder an harder till i worry about the standard crank an start thinking of one like Eddie has from Steve Maney. Oh where will it all end

I just thought of a GREAT use for an otherwise beat-up cylinder with broken fins" Chop it off just above the base flange and use it to test-fit new cams. That way you can peer in and have a close, clear look at the cam followers in place.

(I happen to have a set of trashed cylinders)

Fullauto said:

I'm getting a significant torque increase right off idle. As I've only revved it to 5000 revs in 7000 miles, I am not really that interested in removing bottom end grunt and replacing it in the top end. With 7000 miles up, it still impresses the hell out of me every time I open the throttle. Just going with the flow of traffic and short shifting through the gears is a joy, but when that gap appears, it's just pure go. Top gear performance is great. I run a 22 tooth sprocket and when I had a 23 tooth and a standard motor, it felt a bit breathless, especially getting back to cruising speed after backing off for traffic. Now I feel I could run a 23 tooth with ease. Which, by the way, I fully intend to do. Ben, from British Imports, who built it, is so impressed by it that he rates it above any other Norton he has ridden, even some quite fancied bikes with trick internals. As I've always stated, the beauty and sheer joy of the Norton Commando is it's prodigious low end and mid range and every mod I've made is to accentuate this. Same philosophy with my Fullauto heads. Play to the Norton's strengths. As mine is an all round, everyday bike, I really don't need a strong top end, but, if that's your thing, then go for it.

At 10,000 miles, the engine will be completely stripped to assess the mods made and the effectiveness of the ceramic coating. Results will be posted, warts and all.

Click to expand...

If you've dropped a tooth that makes a considerable difference, tough to make the comparison on the other mods, though I'm sure you are getting some effect.

I have a near stock 850 that wants to pull the riders arms off in the low and midrange. Just open pipes and a tiny compression increase, 21 tooth. That's how they all are if it's a happy motor.
I decided to leave the motor alone after it dragged me up the seven mile long Salmo Creston 8% grade at just under the ton, luggage and all!
Twin Amals don't hurt.

Glen

toppy said:

Oh where will it all end

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Such innocence and naivety..!

worntorn said:

Fullauto said:

I'm getting a significant torque increase right off idle. As I've only revved it to 5000 revs in 7000 miles, I am not really that interested in removing bottom end grunt and replacing it in the top end. With 7000 miles up, it still impresses the hell out of me every time I open the throttle. Just going with the flow of traffic and short shifting through the gears is a joy, but when that gap appears, it's just pure go. Top gear performance is great. I run a 22 tooth sprocket and when I had a 23 tooth and a standard motor, it felt a bit breathless, especially getting back to cruising speed after backing off for traffic. Now I feel I could run a 23 tooth with ease. Which, by the way, I fully intend to do. Ben, from British Imports, who built it, is so impressed by it that he rates it above any other Norton he has ridden, even some quite fancied bikes with trick internals. As I've always stated, the beauty and sheer joy of the Norton Commando is it's prodigious low end and mid range and every mod I've made is to accentuate this. Same philosophy with my Fullauto heads. Play to the Norton's strengths. As mine is an all round, everyday bike, I really don't need a strong top end, but, if that's your thing, then go for it.

At 10,000 miles, the engine will be completely stripped to assess the mods made and the effectiveness of the ceramic coating. Results will be posted, warts and all.

Click to expand...

If you've dropped a tooth that makes a considerable difference, tough to make the comparison on the other mods, though I'm sure you are getting some effect.

I have a near stock 850 that wants to pull the riders arms off in the low and midrange. Just open pipes and a tiny compression increase, 21 tooth. That's how they all are if it's a happy motor.
I decided to leave the motor alone after it dragged me up the seven mile long Salmo Creston 8% grade at just under the ton, luggage and all!
Twin Amals don't hurt.

Glen

Click to expand...

Dropped a tooth? I'm running a 22 tooth and the bike is much stronger than any 850 with a 21 tooth that I've ever ridden. I'll bet you don't get 65 (Imperial) miles per gallon with your twin Anals.

Another interesting thing. I had reason to change the Tri-Spark recently, so I set the timing roughly and proceeded to run the bike for a couple of weeks before it could be set more accurately. It ran very well with just an annoying habit of being hard to start from cold. When it was checked, I'd been running 36 degrees of advance with no ill effects. In previous incarnations, it has always let me know it was unhappy by pinging while accelerating from low revs in warm weather, running 98 octane, even if the timing was correct. I'm now running 95. This tells me that the coatings on the piston tops, ports, combustion chambers and valve heads are working as they should. I can highly recommend the ceramic coating of engine components.

Fullauto said:

worntorn said:

Fullauto said:

I run a 22 tooth sprocket and when I had a 23 tooth and a standard motor, it felt a bit breathless, especially getting back to cruising speed after backing off for traffic.

Click to expand...

Dropped a tooth? I'm running a 22 tooth and the bike is much stronger than any 850 with a 21 tooth that I've ever ridden. I'll bet you don't get 65 (Imperial) miles per gallon with your twin Anals.

Click to expand...

Click to expand...

In the top bit it sounds like you are comparing the modified motor using a 22 tooth against your standard motor packing 23 teeth unless, I'm mistaken?

I get 60+ imperial if I ride like a little old lady and 50-55 if I use the bike harder.

Glen