Norris Cam and Regrind Questions

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swooshdave

swooshdave

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A friend of mine pulled apart his engine (850) and found the cam to be pitted. So he bought a core cam and had it reground.

When he brought the reground cam over I thought it looked strange. It was apparently reground to Megacycle specs(?). I'll try to post the specs soon. The lobes are very steep.

I helped him get the crankshaft pinion off (thanks @Mike T!) so he could split the cases and get the pitted cam out. Then he noticed the pitted cam was marked Norris SS.

Norris Cam and Regrind Questions


Norris Cam and Regrind Questions


Norris Cam and Regrind Questions


Norris Cam and Regrind Questions


So what would you do? I don't know if you can tell how pointy the lobes are in these pictures.

It was done by a local company that I suspect is use to doing cars cams and perhaps big four cylinder motorcycle cams. Not sure how familiar they are with Nortons.

Reground cam looks odd. Norris cam is pitted.
 
It must be the picture, that reground lobe looks like an insane lift speed with a ski jump closure along with minimal duration.
Does it even have a transition over the nose.
 
Your best bet is to rough assemble it in a set of cases. Put on the barrel with the followers. Mount a degree disc on the end of the cam where the sprocket normally fits . Put a pushrod on the follower and then record the lift profile with a dial gauge vs degrees. Remember you usually put the degree disc on the crank. Then compare the profile to those on Dynodave’s site.
 
Norris SS is Megacycle 560-NSS now.
Norris Cam and Regrind Questions


Edit: corrected typo on MC #
 
Last edited:
GN Read the chart you provided...
5600-SS is the 2S combat grind

The Megacycle (norris SS) .359" in/ex is a bit hotter than a 5600-NR but not as hot as a PW3. I have not had access or tested/profiled a similar symetrical cam.

SD The regrind reduces the base circle and may require a new set of push rods...did they re-case harden the cam? I would not use your cams on a bet...maybe a web- hard face weld regrind to a symetrical NSS .359 lift on a full diameter core.
Just get a new NSS cam from megacycle?
 
Here’s what the shop said they reground it to:

Norris Cam and Regrind Questions


Norris Cam and Regrind Questions


I can’t imagine that profile would be kind to a flat lifter.
 
Does anyone have a good used cam for my friend? New cams are not cheap.

Although the ones from Andover aren’t bad, under $250. Unfortunately not in stock.
 
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I have a few cams laying around, but I'm not entirely sure what they are. I think I have a clean stock cam with the matching lifters somewhere. Feel free to have your friend contact me directly. I'm in Seattle at four, two, five, four, eight, six, six, zero, four, zero


First I'd work with the cam grinder, though. If they're at fault I think it would be unusual if they won't guarantee their work.




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Robert_Norton said:
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I have a few cams laying around, but I'm not entirely sure what they are. I think I have a clean stock cam with the matching lifters somewhere. Feel free to have your friend contact me directly. I'm in Seattle at four, two, five, four, eight, six, six, zero, four, zero


First I'd work with the cam grinder, though. If they're at fault I think it would be unusual if they won't guarantee their work.




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Click to expand...

Sweet!
 
Hi Dave
I have a Norris RX. The open and close on the spec you show are very narrow compared to the RX sheet from Norris.
RX intake open 54 BTDC close 82 ABDC
Exhaust open 82 BBDC close 54 ATDC
Overlap 108 degrees
Lift at the valve intake .424 with tappet clearance .006
Exhaust .425 with tappet clearance .008
Physically the cam lobes on mine are much fatter.
 
illf8ed said:
Hi Dave
I have a Norris RX. The open and close on the spec you show are very narrow compared to the RX sheet from Norris.
RX intake open 54 BTDC close 82 ABDC
Exhaust open 82 BBDC close 54 ATDC
Overlap 108 degrees
Lift at the valve intake .424 with tappet clearance .006
Exhaust .425 with tappet clearance .008
Physically the cam lobes on mine are much fatter.
Click to expand...

It would be interesting to see where they got their specs from.
 
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