<VV> Lifter operation

[BobHelt at aol.com]

In a message dated 7/20/2007 8:40:21 AM US Mountain Standard Time,  
chsadek at comcast.net writes:

With all due respect, Bob, not true. That is not how current  hydraulic 
lifters work.  I have OBSERVED the oil going to the  rockers, while priming.  You 
need to disassemble a lifter and take a look  at how it meters oil. I have. 

Chuck S

And.....
 

Smitty Says:  You are usually right about things Bob but not this  time.  
Better go to the garage and take one apart yourself.  I don't  think anyone has 
done more hours of research trying to find out how lifters  operate in the last 
three years than I have.  I lost three sets of heads,  thousands of dollars, 
and in effect, an engine because of the crappy SBC lifters  we are pretty much 
forced to deal with.  I have torn down more lifters than  I would have 
believed existed and they all have one thing in common.
 
 
 
Hi Guys,
I can see that despite your many years of experience and disassembly of  many 
lifters, you both still have an incomplete understanding of how a lifter  
operates. So please allow me to enlighten you so you will know.
 
There are two oil compartments within the SBC or Corvair hydraulic lifters.  
The upper one receives the flow of oil from the gallery and is filled with oil 
 by the pump oil pressure. To get any oil into the lower compartment, oil 
must be  forced past a check valve. This requires some oil pressure to accomplish 
and  only occurs after the upper chamber is completely filled. This is done 
by  use of a metering valve at the top of the upper compartment. When the  
lifter is in operation (engine running) this metering valve is thrown by  inertia, 
first, up against its upper seat (lifter moving down). This   blocks-off any 
flow to the pushrods and rocker box allowing the oil pressure to  force oil 
into the lower chamber. The point here is that unless this flow to the  pushrods 
is blocked-off, the oil won't be forced into the lower compartment.  Then 
when the lifter is moving up, the metering valve is moved off its upper  seat by 
inertia and the oil flow is diverted to the pushrod instead of the lower  
chamber. This lower chamber by the way is what fills with oil to raise the  
internal piston to take up any slack in the valve train.
 
So if you both are correct and you have just installed a new lifter, or  
lifters, without first filling them with oil, both chambers are basically empty  
(maybe containing a little kerosene, and maybe not). So when you  finish engine 
assembly and use your electric drill to run the oil pump, you want  the 
metering valve to be pushed up against its upper seat so as to force oil  into the 
lower chamber. However, as you both assert if THIS DOESN'T HAPPEN, then  oil 
is now allowed to flow only into the upper chamber and from there to the  
pushrods and rocker box, where you now observe it. The problem here is that if  the 
metering valve is allowing oil to flow to the rocker box, then little if any  
oil is actually being forced past the check walve and into the lower chamber, 
 pumping the lifter up. No oil in the lowed chamber means the lifter is not  
pumped up.
 
So AGAIN, I suggest that watching for oil dribbling out of the pushrods  
after installing new lifters and running the oil pump with a drill motor is NOT  
the best way of assuring yourself that the lifters are pumped up. You are only  
seeing oil that has flowed into the upper chamber and then into the pushrods, 
 and little if any going into the lower chamber. You certainly have no  way 
of knowing how much oil is being diverted (if any) into the lower  chamber.
 
Regards,
Bob Helt



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