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Date:         Tue, 1 Feb 2000 02:15:43 -0500
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: 6 mils of lash...
Comments: To: John Rodgers <inua@hiwaay.net>
In-Reply-To:  <3896774E.A46B6FA1@hiwaay.net>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 12:03 AM 2/1/2000 -0600, John Rodgers wrote: >David, from what I know about hydraulic valve lifters, you are pretty much >right >own. Most of my experience is with aircraft engines and they work the same >way.

>http://precisionengine.home.mindspring.com/engine3.htm

You'll be interested in this and related pages...

>correctly...and its been a long time since I went through this....there is >a basic >"lash" setup clearance for engines that have had the valve ttrain worked >on or had >lifters replaced. Once that clearance is set, proper operation of the lifter >piston inside is all that is needed for the valve train clearance to >adjust itself >to zero clearance.

Right. That adjustment shortens the fully extended lifter so that it has a range of operation in both directions. The trouble is that on *some* rebuilt Vanagon engines (like mine) that same adjustment lowers the compression, indicating that the valves are not fully closing.

>As for horizontal operation being a problem, I wonder. Witness the horizontal >aircraft engine. They don't have air entrapment problems with the lifters.

I don't personally think it's a great problem. I have personally assembled and bled a lifter, installed it in an engine, had it get flabby while in the engine, and then had it work the bubble out by itself and become rock-hard again. I don't know the timing, though -- it had been in use for some days when it was observed to be soft, and it was some days later that it was hard again. There's some discussion of air in mushroom-type lifters on the Lycoming page I cited above.

*However* -- it has been observed by many that using an oil filter without an anti-drainback valve often leads to excessive lifter noise on startup, so to that extent I reckon it's a problem.

As far as I'm concerned the real problem is whatever is causing these hydraulic lifters to act like solids. And I hope to find out this spring. As you so correctly point out, the major reason these things exist is so you can just set them up and walk away.

cheers david

David Beierl - Providence, RI http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage" '85 GL "Poor Relation"


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