valve adjustment question

hobot said:

dennisgb you just have not been window shopping much on range of Norton cams and lashes. Just none I've seen had more than .016" listed so huge is relative. Ugh Maybe the NOC guys found out the hard way to list .020" lash instead of vendors recommendation, so some mystery remains.

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Your right about that. Never did a cam. I put bigger valves and high compression head in my 650 BSA Spitfire years ago, but opted against a cam because back then hot cams meant poor reliability and hard starting. The high compression head made that bike a beast to start tho so my thinking wasn't so great back then :shock: It was my first engine build and I learned from the experience. I lean towards reliability now, because I don't have the balls to ride on the high side of the throttle anyway

Nater_Potater said:

That being said, for any given clearance needed, get a feeler gauge that's one-thou larger, and one-thou smaller. This will be your "go no-go" gauge. If you're shooting for .006", a .005" should be easy to insert, whereas a .007" will not go in.

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You made some great points about how the different metals expand and contract, and to be honest I hadn't thought about that. Also, the "go no-go" technique is the way I learned to do this years ago...before I got the feel for the gauge. Very good recommendation here for what sounds like a "newbe".

The comments about whether a thou or so either side of spec is a problem or not. I would tend to agree with this thinking although some engines are hard to start when the valves are too tight. Kawasaki's come to mind. They tend to hammer the valve guides and seats and tighten up over time (probably true of a lot of aluminum head engines), and they become very difficult to start. On those it's better to set them a little on the loose side.

Dont forget if the rocker /tappet thread is worn the clearance is increased when the lock nut is tighted, just when you think its spot on, you re-check to find it bigger!
Dont ask how i know :evil: i think my swearing started whilst doing engine work....Nice pull out of the feeler. nip up the nut,,,re-check......What the F###k!!!
Didnt take long to figure that out, use a thinner feeler to allow!! and save your cursing for women in 4x4's taking the kids school :lol:

Regarding the thermal expansion debate--since you need a larger gap to compensate for the expansion of the aluminum push rods, should I run a smaller gap (say .010) since I have chromoly push rods?

Nater_Potater said:

Nortoniggy said:

It's valve clearance settings are inlet & exhaust zero clearance with pushrods just free to turn! Confusing isn't it?

Ian

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Is that hot or cold?

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They are set cold.

Ian

Steel rods! wow thats going to open an all new can of worms, i would run .006 and check when hot. exhaust valve. note the differance, you may find the gap as enlarged.

nortncom said:

Regarding the thermal expansion debate--since you need a larger gap to compensate for the expansion of the aluminum push rods, should I run a smaller gap (say .010) since I have chromoly push rods?

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I has been suggested more than once by reputable Nortoneers to stay on the loose side if at all, just a thou or 2, and if it seems a little noisy, bring it closer to spec. Too tight is the big no no.

We should remember that these things are not Swiss watches and it is more of a clatter matter than anything else.