Topic: Norris RX3 cam in a 1000cc motor

[gschuld]

I'd like to know more about the Norris RX3 cam.   I have read that the cam has roughly a .380 lift intake and exhaust with about 300 degrees of duration.  Is this correct?  Big Jay, if you read this, I understand that you have the full specs on this cam.  I'd like a look if you wouldn't mind.

Any history on RC Engineering's use of this cam in their motor builds would be helpful.  I have heard that RC used this cam (and other Norris cams) on occasion for Cobra 1000 builds(rather than the RC #327 cam)

A few specific questions:

1- Does anyone have any experience to know what the rpm range(power band) this cam would give a 1000cc motor with RC fully ported heads, lightened and polished rockers, HD springs, aluminum retainers, RC 4 into 1 exhaust? 

2- At roughly what rpm level would I expect the power band to top out?

3- How does this cam compare the RC range of cams? (#295,#315, #327)  The photo below is from the 1971/2 RC Engineering catalog

3- Would the carb airflow requirement be too great for a set of properly jetted/tuned factory K0 carbs at the upper rpm ranges?

4- Keeping to pre 1972 vintage style, other carb options would really be limited to RC weber conversions, modern accelerator pump versions of vintage CR carbs, or having a custom "maxibore" modification done to a set of early factory carbs.  (the bike does need to be functionally streetable, so early race only CR carbs are obviously out)

5- What would be limit(cam wise) for the above 1000cc, RC ported head motor without choking out(cfm wise) a set of factory unmodified K0/K1 carbs on the big end?



Reference to Maxibore carbs:  http://www.x-pipe.com/motorcycle.html

From website below: (quite the sales pitch anyway )

PRECISION MAXI-BOREtm carb boring service allows you to have the best top end air flow - and - even more low end power than you now have. Impossible? MAXI-BOREtm Carb profiles are designed on a flow bench for maximum air flow and are tested on the strip for maximum response and acceleration. Precision cuts allow air to pass over critical jet orifices creating the maximum jet signals possible. Tests have shown that even though a stock 29mm Smoothbore carb outflows stock 28mm mikuni carbs, the stock 28mm carbs actually outperform the Smoothbores at the drag strip, because the Smoothbores have very poor low speed response due to poor jet signals. From these tests it is easy to see why a MAXI-BOREtm 26 or 28mm carb (the "sleeper" carb) easily outperforms the stock Smoothbore; both in terms of throttle response and top end power. It is also easy to see why a MAXI-BOREtm Smoothbore is the best carb money can buy.


Thanks in advance for helping to make me smarter (I can use all the help I can get )

George

[gschuld]

Sorry about the reposts, my computer told me that the thread did not post the first two times.  Apparently they did!

George

[gschuld]

The description page for the RC cams for those curious

[gschuld]

Norris RX3 cam

[Big Jay]

PM me your e-mail address

[gschuld]

thanks Jay!!

[Bill/BentON Racing]

What's the difference between Norris R and R3? Have NOS Norris R. Thanks Bill

[Big Jay]

What's the difference between Norris R and R3? Have NOS Norris R. Thanks Bill

PM me your e-mail address

[Bill/BentON Racing]

Jay,K,thanks,PM on the way,Bill

[dragracer]

Why bore a set of carbs when you can buy new off the shelf Mikuni 34mm RS carbs from CycleX to fit the Honda spacing. The flatslides are fully streetable and easily rejetted for any application and no that expensive.
I really dont have  any feedback to give on the cams but i do have an RC327 in a no bar dragike and the idle is not the best for street use. You would also suffer on the bottom end because the cam doesnèt start to work until mid to top range.

[gschuld]

Post edited a bit.

Dragracer,

    Thanks for the feedback.  I have come to assume that the 327 cam is simply too aggressive for my needs.  I could use a technical reference if you wouldn't mind for a baseline to compare your 327 to say a 295 or 315 cam in a ported headed 1000cc motor.

-I understand that you have a motor with "1030cc and a RC 327 cam on a ported F model head with stock valves." (lifted from an earlier post of yours that I found from 2011)
-could you tell me your compression?
-Roughly your functional power band?  6000-10,000?  higher? lower?

It would be VERY helpful to me to know.

PS  Yes, I am well aware of the Mikuni option.  Not discounting them, but when did these Mikuni sets start showing up on cb750s?  A certain vintage is important to me.  Remember, my bike and RC motor is a 69 diecast K0... trying to keep it as period correct (69 to +/- 72)as feasible.

Thanks

Given the numbers for the Norris cam, I would presume that it too would be too long in duration for my needs(too dead on the bottom end) for my intended purposes.

Anyone with experience with the Norris RX3 cam?

George

[Sam Green Racing]

George, for streetability the 295 gives oodles of power from low down 3000 through to 9800/10000rpm irespective of what else is done.

Sam.

[MRieck]

Why bore a set of carbs when you can buy new off the shelf Mikuni 34mm RS carbs from CycleX to fit the Honda spacing. The flatslides are fully streetable and easily rejetted for any application and no that expensive.
I really dont have  any feedback to give on the cams but i do have an RC327 in a no bar dragike and the idle is not the best for street use. You would also suffer on the bottom end because the cam doesnèt start to work until mid to top range.

Lots of duration Frank....the valves never close. I remember what Rob Muzzy once said....you don't make power if the valves are open. A good port lets you get away with the higher lift, shorter duration cams. Just like modern bikes (and their good ports)

[gschuld]

MRieck, 

OK I'm getting confused... Dynoman's DP 295,315,327 cams ALL have different total lift figures than the RC Engineering catalogs specs.  I thought that these cams were supposed to be the same as the originals?   

From Dynoman's website:

Specs: 295
Total Duration:
306° in   296° EX
Lobe Centers:
105°
Lift:
.390" IN   .360" EX

Lash:
.004" IN    .006" EX

(me again)  Below is the cam specs advertised from the 1971/72 RC Engineering catalog(and it is the same on the 1973 catalog as well)

The RC catalog shows .345 lift intake and exhaust. Dynoman's #295 has .390/.360 lift.  Timing and duration specs are often measured a bit diferently, but overall lobe lift shouldn't vary...  

Sam,

Thanks for your comment regarding your power band.  This info is for your 750A dragbike correct?  Running a MRieck ported and built 836 motor?  And using one of the Dynoman #295 cams (.390/.360 lift)? 

I am FAR from an expect on bike cams, but I have some experience with HIPO small block chevys.  I found it very noticeable that a high performance cam gets "less aggressive" as the displacement of the motor increases.  For example, a cam that is pretty hot in a 350 is noticeably more mild(dropping the powerband rpms) in a 400 small block assuming the comparable compression, heads, exhaust, etc.  So if the #295 cam in a well ported 836 has great torque and pulls from 3000 to 9500/10000, the SAME cam in a larger displacement RC ported 1000cc motor would likely start pulling at a similar rpm and peak at a lower rpm, say 8500/9500!  Plus or minus...?

Perhaps a 315 cam in a ported 1000cc motor would be comparable (power band wise) to a 295 cam in a ported 836 motor? Reasonable?

What I am getting at, of course, is trying to decide on a RC cam that would suit me best( it currently has a reduced base circle(.87) reground .365/.365 cam in it now, with lash caps, unknown profile or maker).  I'm looking for a reasonably streetable powerband that is not intended to rev to the moon.  I'd probably be happy if it's all done by 9500 max, possibly lower...  The 295 is the safest bet naturally, but wondering if the 315 would work as well considering the large displacement tends to mellow out larger cams. 

And why does Dynoman's #295 cam have much higher lift specs than the RC #295 cam that it is supposed to be a direct "copy" of?

George

 

[754]

 How you ride and where you live makes a difference to.. We now live in a no fun zone.
 With Webers, 836, unported head, 315 cam, it pulls quite hard at 4K, but really gets more exciting higher up. I doubt it would ever pull like that with stock carbs.

 So everything really depends. On your combination, some overly hot cams with stock carbs.. Are no joy unless they are winding out at high rpms..- i had one like that.

[gschuld]

754,

   Thanks for the reference.  I'm a bit concerned that factory K0 carbs will run out of cfm at the higher rpms on a 1000cc motor.  I wasn't necessarily concerned with factory carbs being able to control at low-mid revs though.  Perhaps I should be...

It's one of the reasons that I would prefer to have a cam that has short enough duration/overlap to offer a reasonably strong off idle bottom end pull.  This should also limit the upper end power band to reasonably low rpm peak, say 8500-9000 or so making it les likely that the K0 carbs will present a problematic restriction(not that I am discounting the option to put an RC Weber conversion on the motor).   I don't want to feel the need to blast to 10000 to "get the power out".  Not my thing...  I generally prefer grunty torque over HP.  Valve trains tends to prefer it that way as well.

George

[Retro Rocket]

From everything i have read, webers make more torque on these engines, so better bottom end and mid range response...

[gschuld]

I have heard some of the same comments.  Have a spare RC weber setup laying around?   I ...may ...be in the market!

George

[Retro Rocket]

I have heard some of the same comments.  Have a spare RC weber setup laying around?   I ...may ...be in the market!

George

Actually, i do....    Some one else on the forum has first go at it though George....

[BLUE71TURBO]

I have heard some of the same comments.  Have a spare RC weber setup laying around?   I ...may ...be in the market!

George

Actually, i do....    Some one else on the forum has first go at it though George....

                   So what yer actually saying is " Snooze you loose " right ?  LOL      Yea, i wish that i had not sold my webber setup.      But i needed the  $$$$  to put towards my turbo setup.  I needed to go FASTER !  Now i'm thinking of a little NITROUS to the old blue horse to getty up some more.      

[Bill/BentON Racing]

We were running Megacycle 125/75 originally with Mikes Stage VI head,836 JE kit
Tried 295,better down low
Then went to Kenny,CycleX Wiseco 915 his specs,piston weighs 154.3 grams,stock 161.xx!!!!! Put 125/75 back in,noticeable more torque and hp,3rd run 87.07 rwhp,stock 39.8!!(Autos lose 10-12 rwhp cause of T/C) Best was 79.xx with same carbs,80.xx with 29mm smoothbores
Then went back to 295.....60fts under 2.0,1.9's all day long,immediately bested ET was 12.36,ran 12.2's time and time again,ran best so far of 12.18! 11's sometime this year.Norris R .357 lift,280 duration.More what you looking for? Bill

[gschuld]

Retro Rocket,

    Really....?  Go figure.  I've been having "You snooze, you loose" moments on the last few items lately.  A vintage fairing, a set of KO carbs, another set of Webers...  Have I been black listed or something .

No worries, but if the other party bails, let me know.  Trying to cover my bases...

Dellorto "DHLA40" carbs on cast cb750 manifolds are the same "Webers" correct, as in Dellorto just licensed the Weber design and put their name on them right?   

Bil,

  Yes, helpful thanks.  As I have figured, the 315 cam wouldn't likely be very streetable unless the displacement is large and the compression is fairly healthy.

George

[754]

 I loved the 315. On the street..in fact i like it so much that i decided to forgo. Ultimate top end power at the expense of torque....
 You got ask yourself HONESTLY where do you spend most of your time..if its midrange too 9 k its a fun cam..with the combo I ran.. And it will easily pull hard to 10,5 or 11k..
 I have a Norris in the tracker.. Never got to run thru the gears,but
It feels strong..might be an R grind..and the motor has Webers..