REFLECTOR: Setting Valve Clearance

[Laurence Coen]

Tec,

Your answer on lifter leak down is incorrect.  If hydraulic lifters couldn't bleed down they wouldn't work.  To quote the Franklin Rebuild Manual, "Leak-down rate is meant the rate at which oil escapes between the cylinder and plunger of the hydraulic unit."
The English in the quote is a function of the translation from Polish but the meaning is clear. The answer to the question is yes with a caveat.  When the valve closes, the spring on the plunger will pump the lifter back up.  This would require you to maintain pressure on the pushrod end of the rocker to prevent this from happening as you rotated the engine back to top dead center.  Hydraulic lifters function are to compensate for dimensional changes that take place due to heating and cooling and therefore must be able to adjust in both directions.

Unless the lifter itself is suspect, it isn't necessary to remove it when a cylinder is pulled.

Larry Coen
N136LC
SE/RG Franklin/IVO


From: HYTEC45 at aol.com 
Sent: Thursday, April 23, 2009 3:11 PM
To: reflector at tvbf.org 
Subject: Re: REFLECTOR: Settig Valve Clearance


In a message dated 4/23/2009 1:01:22 PM Pacific Daylight Time, aminetech at bluefrog.com writes:
  If I position the engine with the valve open, will the valve spring exert enough force to bleed the lifter?
   No, thier is a check valve in the unit that will not allow this.
  Also, if I'm removing the cylinder, is bleeding the lifter by pressure acceptable, of should I remove the lifter and disassemble it?
  Remove by fishing out with a hooked piece of safety wire from the follower body, and unseat the check ball from below with a brass or like punch to compress the unit.



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