Quote:It depends on what you call 'vibrate' If it is clearly a bad shake, then there is something wrong, something's out of balance.
The stock, short stroke A series engines [A10, 1200, A12, A12A & A13] will rev to about 6,000 without any bad vibrations as this is the factory redline on the tach.

If it shakes bad, then first you need to identify the cause & rectify it as more revs will just mean more vibration.

so it can rev safely a simple balance job would be a good step....and shouldnt be a last step

thanks man i have 7k valve springs but dont know what sort of cam to get or where to get one i dont know what all the lift and stuff means could you recommend a decent upgrade one

yes not for 6000rpm but he asked how to get it reving faster so i am talking 7 to 8000rpm

None of that is needed "normally".

Normally an A12 will rev to 6000 rpm without any unusual vibration.

first thing would be an electronic dizzy then cam and valv springs some porting of the head and valve work and if that dosent work balence the crank and flywheel

A12 is designed to rev to 6,000 rpm.

just wondering what it is safe to rev a stock a12 to as mine vibrates at about 5000 is that nornal and what do i do to get it to rev out further