Combat with Norris RX camshaft

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ILLF8ED

ILLF8ED

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Finally got the Engine dialed in. in a previous string had mentioned my combat engined 72 roadster had a standard cam that was causing considerable pinging. The comment I read about hot rod idle is definitely true. Engine revs much easier now and the power surge is just under 5000rpms. Would not recommend this tune for anyone that likes an 850, but if you don't mind the rough idle, it's fun :)
Spent about a grand on the head getting new valve seats, guides and black diamond valves. got the intake guides that are machined for seals, so no more smoking.
 
That a big grin to read. I'm going with a big cam to stifle detonation in a hi CR project, so double happy for both of us. Would love to hear video of the 'rough' cammy idle.
 
Weekend before this took the combat out for a shake down. Guess it shook too hard. All the cylinder base nuts came loose and the cylinder was up off the crankcase by a quarter inch. Just got it back together today and gave it about a mile. Won't make the mistake of going anywhere again for a while without wrenches. Runs pretty nice even with the rumbling idle. Can't brag about it idling at 500 rpms. It needs at least 1200 rpms to stay running. I know how to post still photos, but don't have the knowledge yet to post videos with sound.
 
Its not hard for me to believe a Combat engine is elastic at hi rpm but how the heck could the nuts back off like you say? If ya do loctite em remember to torch em good to remove. 1200 idle ain't turbine zone but still annoying at rest. Raising the CR helps lower the idle zone of aggressive cams, w/o detonation once on cam too. Hope ya grin involuntary every time out with tools to get back on... At the hi rpms it takes to kick up cam heels, its handy to have a test light in kit too.
 
ya hobot, I think I talked to you about my bike too, I can usually idle 800 - 1000 with the norris D and combat head on domed pistons (750) on a 850 bottom end though running twin miki's. Better ign might help a guy out too though, running points
 
illf8ed said:
Finally got the Engine dialed in. in a previous string had mentioned my combat engined 72 roadster had a standard cam that was causing considerable pinging. The comment I read about hot rod idle is definitely true. Engine revs much easier now and the power surge is just under 5000rpms. Would not recommend this tune for anyone that likes an 850, but if you don't mind the rough idle, it's fun :)
Spent about a grand on the head getting new valve seats, guides and black diamond valves. got the intake guides that are machined for seals, so no more smoking.
Click to expand...

Say Dave, this thread is titled Norris RX camshaft.

I have one and raced with it. Sent it to Dave Comeau for profiling, plotting and publishing. You are the first I have heard who has mentioned the Norris RX.

Are you running it now. Was this an after market cam? Trying to learn a little bit about the history of it.
 
I seem to recall installing a Norris R cam in my 69 Commado some 40 years ago. The one thing I recall, it ran like a thief in the night..
 
Unread postby DaveK » Sun May 06, 2012 9:53 pm
ya hobot, I think I talked to you about my bike too, I can usually idle 800 - 1000 with the norris D and combat head on domed pistons (750) on a 850 bottom end though running twin miki's. Better ign might help a guy out too though, running points
Click to expand...

OH my Davek, this is music to my ears in a variety of ways. When I had Combat AAU issues that wouldn't idle back below ~1500 rpm it made my toe nails to hair roots hurt trying to travel THE Gravel w/o any engine drag ability, just same speed or even increase on let off of throttle and down shifts. Norris D is a bit more cam than the RX so even better to know they can idle reasonably ok. DynoDave's Atlantic-green site has the RX cam graphed. These bigger cams all work better, especially down low with increase in CR, and as anciently accepted tend to suppress detonation with increased CR. A down-dirty online Calculator implies the RX and D can decrease the effective CR about 2 points below static CR. My 920 10:5 CR with Norris D should function like 7.5 CR down low - then bump up CR to over 12 when rpm gets going. Glad no one mentioning issues with valve clash.
 
Anybody have a catalog listing (if it existed) of the cams Norris offered. My understanding of the history is that Megacycle took ownership of some or all of the Norris "stuff" and maybe enhanced on a few of the Norris features on some or all of the cams.

With the RX grind, thief in the night - that is my recollection. I ran 1-3/8" headers to shortish reverse megaphones, stock head, stock 32mm Amals and around 10:1 compression ratio.
 
As Norton and others supplied the factory grinds, Norris is mostly known for their couple or 3 more aggressive cams as listed in the MegaCycle catalogs. I only know of RX and D, but might be a 3rd milder one. A couple of late drag racers I interviewed in early 2000's both said the Norton's LOVED the Norris D+, so much so the AMC tranny spilled guts on track so went with Harley tranny. Don't know what TC used, will have to ask.
 
I'm relying on a 67 year old memory here. It may have well been a RX grind rather than a R.
 
I may not correctly recall the grind, but I do recall the trophy I got at the drag strip running that cam. First time ever at the strip, made a practice pass and one run. Posted fastest time for the day. That was in Minnesota, not Arkansas. Never raced at a drag strip again. I did, however, bag many a street race. I know there's a guy that had a Kawy triple who probably still wonders what happened. Now, I won't tell you about my one time foray into motocross racing with my new 1972 Yammy DT2-MX. It was down right embarrassing.
 
JimC,

Some excellent reading and history there although the Norris R and RX designation still seem to be a bit of an enigma; much of the references are to a cam lobe design for a Triumph.

So: "As a bit of trivia, "Norris" was the first name of both partners, Norris Baronian and Norris Barsumian (both Armenian I would guess)."

One Norris started as a shop foreman for Isky Cams. Norris provided cams for Jungle Jim (Lieberman) dragster. Jungle Jim's his side kick was Jungle Pam - in every school boys wildest dreams.
 
I would swear it was a R grind I used. Of course, there are times I think I may have dated Raquel Welch, too.
 
Yep, that is the RX.

Maybe the Megacycle 56-0NR cam is the old Norris "R" cam.

The Atlantic Green graphs indicate that the 56-0NR has about 0.025" less lift on both lobes and less overlap when compared to the RX.
 
JimC said:
I would swear it was a R grind I used. Of course, there are times I think I may have dated Raquel Welch, too.
Click to expand...

Not to worry, there was an R grind. See below.

Combat with Norris RX camshaft


Ken
 
Thanks. So, no doubt I really did date Raquel Welch then.

BTW, I don't see a RX grind. Was there one?
 
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