Quote:
Originally Posted by Tim Falce
The problem is that the cams are on my bench not in the engine.
|
If you can hold the cam in something like a lathe , with a protractor on the end , & a dial gauge onto the lobes .Then you can turn it to get the readings .
Assuming it is a pushrod engine , you know what the valve clearances are ,then you need to know if the rockers are 1 to 1 ratio so you can tell the moment the valves would open if it was in the engine .
Set the dial gauge onto the heel of the cam , then turn the camshaft until the dial goes up to the , [ corrected ]clearance .Make a note of that reading from the protractor . Then turn the cam back across the heel until the dial reads the clearance again . Those 2 protractor readings will give the dwell angle in degrees . [ Could be something like 250 odd degrees ] .
Take that figure from 360 , double it & you will have the valve open duration .
It is a bit more difficult if it is not in the engine , especially if you have to work out rocker ratio .