Valve Spring # Question

6

67Fastbackfan

New member
Is there some type of idea for getting an RPM limit based on valve spring #'s

Such as:
10.8 = 6,000 RPM
14 = 6500 RPM
18 = 7000 RPM
ETC....

Asking because my son has a BSP and we're looking for a little more RPMs. No rules here, just riding around on a yard kart.

Thanks
 
Believe that on a stocker engine, more spring than neccesary will hurt power more than it will help unless you have the supporting mods to go with the added spring pressure, such as bigger bore and stroke, more compression, ported/polished head, bigger valves and valve job, carb upgrade, things like that. You would at least want a bigger cam with more lift and duration and maybe some ratio rockers, and have a good flywheel on the engine if you plan on turning more than 6000. But on a stock bsp engine i would stick with a good set of 10.8 springs or find some around 12-14lbs if your gonna be turning it hard.
 
Are you floating the valves now? Yard karts generally do not have this problem, the combination of big heavy wheels, inefficient drive train and weight keep the engine RPM in control. If you are looking for more speed or power I would look at other avenues before I turned to increasing RPM, trim weight, alignment, tire size pressure, gearing etc.

Do you have a tach installed?
 
No tach, engine just gives up pull around 35-40mph @ max RPM. I'm trying to stay away from gear changes to keep a good bottom end on it. Currently running all the normal BSP parts, weinie pipe, filter adapter, re-jet, BSP-2 cam.
 
Advance timing to 32* If not hemi try a a 1.3 rocker on intake valve,keep valve lash cold@.001 is it floating the valves or are you just looking for more Yank???
 
I would get rid of the weinie pipe. Get you good big pipe off classifieds . It help your engine breath better . Help with more power.
 
67Fastbackfan said:
No tach, engine just gives up pull around 35-40mph @ max RPM. I'm trying to stay away from gear changes to keep a good bottom end on it. Currently running all the normal BSP parts, weinie pipe, filter adapter, re-jet, BSP-2 cam.
Click to expand...
If you don't have a 'tech'...you hv NO idea what you have. If the valve springs are weak, you could be floating the valves and loosing power. What is your gear ratio(?) Maybe it's on 'nose-bleed' at 35-40mph!! Many un-knowns involved. JMO
 
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