Norris cams info

Hope you guys can help me.

I live in the UK and am building a z1000 motor which is going into a Harris Magnum chassis for road racing. On impulse I have bought a set of Norris 425 cams but can find no information on their specification ie lift/duration and wether they are too hot for road racing and better suited to the drag strip. In paticular, anybody know if I have to use these cams with the shim under bucket arrangement and what the tappet clearance (valve lash?)should be?

Any info/help gratefully received.

I believe those are .425 lift and about
265 duration.You will need underbucket
shims.They should work good on the track,
just watch your redline.

I've read where if you are roadracing, you might want to advance your intake cams a couple degrees to help it pull off the corners. I have never roadraced so take this as someone else's idea, but it makes sense as advancing your intake cam will give you more power down low without hurting your top-end much which is probably more important than all-out HP like at the drags.

megacycle cams 415-472-3195. They sent me a cam card for norris .407 cams. op.30 cl.70 280deg. duration .020lift. The op. and cl. numbers are same as stock. The difference is that with the stock cams the valve BEGINS to open at 30deg and CLOSES at 70deg. The norris cam has the valve already open to .020 lift at 30deg and at 70deg it's still open .020. Both cams are spec'd using zero lash. Kasasaki took the op. and cl. from the axact piont of op. and cl. The norris op. and cl. numbers using kaw's method are closer to 35 and 75. You may want to give mega a call: since your cam has slightly more lift it may have also have more duration. The .407 cam card lists 110 110 lc. I have mine set at 109 and 111. After all the studies I've done I feel safe to say that advancing the intake to 107 should be about the best place to start. effects of advancing the intake are non linear. As you advance the top end tapers bottom comes up etc. Once you reach a certain point, a very drastic drop in top end occurs, as well as a titanic increase in low torque. With too much advancement, the motor literally won't run past a given rpm. What you are looking for is a good broad power band. 107 may be too advanced, but it will surely set the timing on the edge of both worlds. Then if you need more top move it up to 109 or 110. THing is you need to experience the motor when it makes strong torque. That way you know how much it has and what it's good for. You can always change lobe centers and mark your old spot. Starting in the middle the less you'll fiddle. Check the valve to piston clearance once your dailed (intake side) just to double check. I use a piece of solder. This way I can check it 5 times in a couple seconds.

Post edited by: nads.com, at: 2007/09/24 16:47

lash for the .407 is .006

Norris 425
Exhaust
Open 70° BBDC Clost 30° ATDC

Intake
Open 30° BTDC, Close 70° ABDC

Lift .425 Duration 280° @ .020"

Lash .006 cold

Post edited by: APE Jay, at: 2007/09/24 18:30

Blimey!!!

Thanks to all the replies - So helpful.

Especially to the APE guy - Is this cam suitable for road race or is it a bit "hot" for that? Also, anybody have a recommendation for carbs - I am tempted to go for 29mm smoothbores as I think they may be a bit easier to tune and more torquey than 33mm.

Any thoughts???

Harris Racer wrote:

...Also, anybody have a recommendation for carbs - I am tempted to go for 29mm smoothbores as I think they may be a bit easier to tune and more torquey than 33mm. Any thoughts???

33 smoothies

Harris Racer wrote:

Blimey!!!

Thanks to all the replies - So helpful.

Especially to the APE guy - Is this cam suitable for road race or is it a bit "hot" for that? Also, anybody have a recommendation for carbs - I am tempted to go for 29mm smoothbores as I think they may be a bit easier to tune and more torquey than 33mm.

Any thoughts???

You don't say anything about the rest of the motor? Bore, compression, head-work etc. Between the 29s and the 33s, 29s would be my choice. SOB valve gear with heavy springs for whatever cams you end up with is a good idea. The configuration of the track you race on should be a consideration in your motor build also.

With those cams I recommend the 33s.