Camshaft nomenclature

Gumbo

Gumbo

Junior member
Location
Cirencester
Would someone explain why cams are referred to as 4C, A11 etc ?

Also, why do the above have different wheels?
Is it to provide a different opening timing ( if that makes sense)?

Just wondering...

Tony
 
Tony, yep, different cams with different designations and different specs, with model-specific sprockets to provide (approximately) correct cam timing. Most triples had a mild A11 cam, there was an even milder A12 used in some European markets, the Jotas mostly had 4/cs, and there was a racing only 7/c grind too. 120s used different profiles again, the F1 profile on a 180 cam works just great.
Go to http://www.laverdamania.net/cams.htm for definitive specs.

Ken
 
I always thought it was to do with rev range where most usable power started to be made.

4c, anything under 4500RPM knock on the door.
5c, 5000RPM + =  :D
6c, picks up sticks at 6000RPM
7c, over 7000RPM heaven, for a brief moment.

Am I wrong?
 
Gumbo said:
Would someone explain why cams are referred to as 4C, A11 etc ?

Also, why do the above have different wheels?
Is it to provide a different opening timing ( if that makes sense)?

Just wondering...

Tony
Click to expand...

Yep, that's about right.

Is there a problem with what you have? If so there are really quite a lot of options!

J
 
No, no problem. I was just interested in why they were named as they are.
What does the C in 4C stand for? Why A11 etc?
Just curious..

Tony
 
A11 - Antonio designed it at 11:00AM
4C - 4:00PM and Carlo finally finished his version, a bit lumpy but
7C - Carlo did some overtime
 
Gumbo said:
No, no problem. I was just interested in why they were named as they are.
What does the C in 4C stand for? Why A11 etc?
Just curious..

Tony
Click to expand...

Just a guess:
C => Competitione => Race-Camshaft
A => Ambulante => Road-Camshaft

But - as said, no knowledge, just a guess...

4, 7 etc. are simply different versions I guess. I am also not sure if a 7/C on a 180? engine has the same cam profile as a 7/C on 750 engine. But I guess they are the same...?!? Also not sure why the A cams are numbered in a different way with a) leading letter and b) 2 digit numbers.

To make things even worse, there is the F1 Cam for RGx-Series bikes and the P1, which is the racing equivalent...

But to be honest, I don't give a damn why they named it that way, I just know which to use and that's it.  ;)
 
I just know which to use and that's it  
Click to expand...

same cam profile as a 7/C on 750 engine. But I guess they are the same  
Click to expand...

Do you know which 750 uses the 7/C cam Lothar? - Never heard of that one - unless you mean Zane models? -750 profiles are totally different from triples as they have rockers with a non 1:1 ratio. - Regards - Phil
 
Davo said:
A11 - Antonio designed it at 11:00AM
4C - 4:00PM and Carlo finally finished his version, a bit lumpy but
7C - Carlo did some overtime
Click to expand...

I had a 7C in a Jota  (puke) ............... Carlo shouldn't have been paid overtime that night!
 
chrisk said:
I had a 7C in a Jota  (puke) ............... Carlo shouldn't have been paid overtime that night!
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Cannot agree, Chris.

Got a pair of 7C in the track bike, runs nicely with the open megga, pulls strong from about 3500 to... as far as you like!  Any sort of silencer stifles them imediately.

piet
 
sfcpiet said:
Cannot agree, Chris.

Got a pair of 7C in the track bike, runs nicely with the open megga, pulls strong from about 3500 to... as far as you like!  Any sort of silencer stifles them imediately.

piet
Click to expand...

:o Mine must have been up the shit then, cause at 6500 it took off like a rocket, at 3500 it wouldn't pull the skin of custard!
 
sfcpiet said:
Cannot agree, Chris.

Got a pair of 7C in the track bike, runs nicely with the open megga, pulls strong from about 3500 to... as far as you like!  Any sort of silencer stifles them imediately.

piet
Click to expand...

Track is the only place for 7C cams, in my opinion. Acquired a new pair as part of a spares deal, back in the '90s and put them in a high comp Mirage. Bugger all below about 4500 and only really came alive above 6000 - 6500. Useless on the road. Sold them for a tenner  :D
 
A friend of mine has 7C cams in his Jota. I've not ridden his bike (must do a swap one of these days), but he reckons they're quite OK for road use. Maybe it depends on how they're dialled in.
 
Dellortoman said:
A friend of mine has 7C cams in his Jota. I've not ridden his bike (must do a swap one of these days), but he reckons they're quite OK for road use. Maybe it depends on how they're dialled in.
Click to expand...

Not only. It also depends on the whole other setup. Many people think that they can only change the cams and they'll make a rocket out of their bike. It is very likely that the carb- and exhaust setup need to be adjusted to fit the new cams. Just think of it: how does a 7C produce more power? it opens the valves early and longer so that the engine can breath better. If the exhaust does not fit to that, the back-pressure in the exhaust system spoils the cams attempts for more power. If the carbs are set slightly wrong, you can not make use of the extra filling etc. etc.

Friend of mine did almost 50 test runs on a dyno with different setups of exhausts, from totally muffled to totally open, from 32mm headers to 40mm headers, from small collector to large one. Only one setup really worked well and he told me that he found the optimal exhaust system for Laverda. When I asked him if he had checked the AFR during these runs and he said "no", I told him to bin all the test results and just start all over again... That was proven by the fact that when I was at SR-Racing for my 1000 SFC's exhaust construction, we found that with the old exhaust, the AFR was OK while with the new one, it was way to rich. We had to drop the needle by 2 notches (Keihin carbs have 5 instead of 3 as with the Dell'Orto) to compensate that. Still it was between 12,5 and 13. (before it was at 9...)
 
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