Heymow - Lawnmower Racing Forum

Engine Help => Briggs OHV & Vanguard => Topic started by: Todd99 on October 31, 2013, 09:16:36 am

Title: cam lift
Post by: Todd99 on October 31, 2013, 09:16:36 am

Can someone tell me how to determine the lift on a cam please?

Title: Re: cam lift
Post by: willenglish on October 31, 2013, 10:29:33 am

Lift is the part of the cam lobe above the base circle. Measure the entire  lobe of the cam...then determine the base circle...the differance between the two numbers is the lift. On a flathead motor..this is your total lift...minus whatever clearance you have.  On a ohv motor..the rocker arms have an effect also. According to the ratio of the rocker arm..the lift can be considerably different. To find the total lift there...it must be measured installed..at the valve.

Title: Re: cam lift
Post by: Huffy044 on October 31, 2013, 11:20:37 am

I use a dial indicator on the push rod

Title: Re: cam lift
Post by: Todd99 on October 31, 2013, 11:37:31 am

Thank you very much guys for your help!!

Title: Re: cam lift
Post by: Otto on October 31, 2013, 12:22:43 pm

If you have .300 lobe x1.5 rocker you will .450 lift .then correct way to check is put springs and retainers you will use on head.put head on with pushrods you are using.put dial indicator on spring retainer and roll engine over to max lift.this way you can see how much deflection you have.if way less than .450 you need better components .with more rpm/ more deflection .