PW3 Cam nut

I am installing a PW3 using a new AN camshaft nut....but it is too tight on the thread to go all the way on.....

I have tried the nut on both a standard cam and a Norris cam, absolutely fine.

So, is the PW3 thread different?

Anybody know what the thread is?

SteveA wrote;

So, is the PW3 thread different?

Click to expand...

Not as far as I'm aware, as I used the standard nut on my PW3.
Is the PW3 new, because if it is I'd be sending it back to the vendor as it sounds as if the threads have been cut poorly.

As above; and request for a nut ,that fits!

Should be easy to chase it with a 3/4-20 die.

Its chilled cast iron so yes a die will clean it up, also means you can't torque the nut up using the factory figures or the end of the cam will break off.

kommando said:

Its chilled cast iron so yes a die will clean it up, also means you can't torque the nut up using the factory figures or the end of the cam will break off.

Click to expand...

I know, and that means I am taking a lot of care with it....

If its not too bad try some grinding paste and run the nut on and off a few times.

Dont torque it too much. You will snap the cast iron.

Sounds like a job for a thread gauge
/Steve.

It seems a small batch is affected by this problem, my supplier, Norman White, is being very helpful.

If you bought a PW3 recently check the standard 3/4" - 20 nut fits cleany before assembly. There was nothing obvious with the thread until I tried to run the nut on. Moral to me is that I should have done that before bolting the cases up.....they will be coming apart again....I guess I could use the practice....

This is my first Commando engine build for a very long time and in those days I had none of these type of problems. It pays to check , check and check again it seems. These things help imprint that. Patience is not one of my virtues, I need to improve that :wink:

SteveA said:

It seems a small batch is affected by this problem, my supplier, Norman White, is being very helpful.

If you bought a PW3 recently check the standard 3/4" - 20 nut fits cleany before assembly. There was nothing obvious with the thread until I tried to run the nut on. Moral to me is that I should have done that before bolting the cases up.....they will be coming apart again....I guess I could use the practice....

This is my first Commando engine build for a very long time and in those days I had none of these type of problems. It pays to check , check and check again it seems. These things help imprint that. Patience is not one of my virtues, I need to improve that :wink:

Click to expand...

I would also check the thread inside the Cam which takes the AAU or EI rotor bolt. If that is wrong, then the Cam will be out again! Does the PW3 have a different thread for this? In which case you'd need the appropriate bolt. I guess the spec sheet for the PW3 should show this.

The PW3 cam is regularly mentioned as a good product. If you get something like the main thread on the cam wrong/faulty, what are the chances of rest of the cam being accurate I wonder? I'd be checking all that before fitting one too :roll: correctly

Old Bloke said:

SteveA said:

It seems a small batch is affected by this problem, my supplier, Norman White, is being very helpful.

If you bought a PW3 recently check the standard 3/4" - 20 nut fits cleany before assembly. There was nothing obvious with the thread until I tried to run the nut on. Moral to me is that I should have done that before bolting the cases up.....they will be coming apart again....I guess I could use the practice....

This is my first Commando engine build for a very long time and in those days I had none of these type of problems. It pays to check , check and check again it seems. These things help imprint that. Patience is not one of my virtues, I need to improve that :wink:

Click to expand...

I would also check the thread inside the Cam which takes the AAU or EI rotor bolt. If that is wrong, then the Cam will be out again! Does the PW3 have a different thread for this? In which case you'd need the appropriate bolt. I guess the spec sheet for the PW3 should show this.

The PW3 cam is regularly mentioned as a good product. If you get something like the main thread on the cam wrong/faulty, what are the chances of rest of the cam being accurate I wonder? I'd be checking all that before fitting one too :roll: correctly

Click to expand...

The internal thread is correct and as standard Norton, but mine is not cut as deep as an original cam, there may be a reason for that it being different material. My oil seal tool wont go right in, but, I can cut that down if the replacement is the same, but in any case my ignition runs off the crank. If you refer to other forum threads about PW3 timing figures you should not be too surprised to know this cam was the one in question. It has been measured, accurately. Hopefully the issues are limited to this batch, I am not sure teh replacement will get measured in teh same way, running out of time.

The PW3 is a well respected (and copied!) cam profile from a very competent designer and sold by two suppliers who have good reputations.

I am not rushing off to get an alternative, nor am I slagging off those suppliers. I think with hindsight the alternative I considered would have eliminated two problems....ref to thread on cam follower fit, which would not have happened when fitting BSA style followers and blocks!

Though you will find comments from Jim that it took a while to get the quality of his cams to the standard required! abeit in his case for another issue (keyway location).

Perhaps I should have just spent the extra.....but we will see how the replacement PW3 works out, The PW3 is what I wanted to use so I will stick with it at least as far as experiencing it run! If I replace it later the replacement will in any case be a close copy as far as performance is concerned.

I agree there's nothing wrong with the PW3 valve timing, but you shouldn't necessarily have to spend more than what the PW3 already costs in order to make sure you get a properly made cam.

Al-otment said:

I agree there's nothing wrong with the PW3 valve timing, but you shouldn't necessarily have to spend more than what the PW3 already costs in order to make sure you get a properly made cam.

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Agreed, the PW3 is not priced that far different to a 4S or Maney cam, but assuming you price a set of followers, rods and the cam, with UK shipping, compared to importing a JS Stage two kit from the US, and paying import charges it is a smaller investment.

We will see how it works as a race cam, that is the most important issue. Evidence is that it should work pretty well.