cams does anyone have info on the differences
 

I see cams for sale all the time

A8, A10, A12, and so on
But I never see any info on say the rpm range or what they do or how they perform.

Can anyone shed some light on the cams?

There are several different manufacturer and there's no set standard for what they mean. Some speculate that it means the amount of lift you get but also some have said it can vary too because some are torque tuned, some HP tuned. All you can go by realistically is the seller's word and even then they might not know.

It's a crapshoot basically. And for most people putting in the cam gives little increase in power anyways. You tend to get more reliable power by going with a big head valve or 4 valve head than trying to mess with cams.

So unless you've done all the other power mods, like bbk, intake, exhaust, carb retune, big valve head/4 valve head, the cam should be the last on the list of mods.

Your A8 and A9 cams are for your high rpms and top end, as you go with a bigger number A10, A12 etc, those are for more LOW END torque and you loose rpms.
Lefty

From what I have done and seen, and from what everyone else has said, the 4 valve head is about useless. The results you get out of it do not justify the price alone, not to mention the aggravation of installing it.
The numbers of the cams are a sort of name really. I have seen some cams with numbers punched into it about the Lift and Length of that the lobes produce. For an accurate number, you would have to measure with a Caliper and do the math yourself.
However, I do know that everyone I have seen upgrade cams, have put out a noticeable difference in performance.
My father put an A14 on his and it gained about 15mph, lowering the RPMs by about 1k.
For the best performance output versus price/work, in my opinion, is the Torque Spring.

Back to the subject, on a stock engine set(minus Varo weights) an A12 cam does a pretty decent job for the GY6 150.

according to a cam seller
Basically A-9 is best for top end speed. A10-A11 best for torque. A-12-A13 is popular for midrange power. and A14-A15 are usually for Racing and require upgraded valve springs, and Titanium retainers

but without torque you don't have top speed