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Author Topic: Roller rockers  (Read 46314 times)

dkwflight

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Re: Roller rockers
« Reply #120 on: August 11, 2006, 02:29:02 AM »
Hi I once flew and tried to adjust the brake system on an ultralight airplane with a brake system almost exactly like the hydrolic system Guy proposed. What a pain in the ass. Every time the weather changed the brakes would drag!. There was no free play in the system. the typical car brake system has a port to the reservoir. This port alows the oil to flow back and forth to the cylinders when the brakes are not in use with weatther- temp changes . Then when pressure is applied to the pedal the master cylinder moves some small distance before the port is closed and pressure is built up to move the brake pads. a similar type of setup would be required in a valve opertating system. Even better would be a way of having flow through the lines to remove dirt build up in the system. Have you ever bled a brake system on an old car and have sludge come out of the wheel cylinder?
Dennis
« Last Edit: August 11, 2006, 02:31:55 AM by dkwflight »
28/2 powersolutions JKSon -20k gen head
Still in devlopment for 24/7 operation, 77 hours running time

Doug

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Re: Roller rockers
« Reply #121 on: August 11, 2006, 02:55:34 AM »
Well I keep spinning this around in my head and I think its probably possible, but I don't know enough about hydraulics to be sure if engine oil is fluid enough to snap open a valve 500 times a minut. I don't know if this presents heating problems or what the frictional losses would be. But I think it would be very cool, quite and offer the possibility of closing up the head to protect the valves. If you had a real oil pump scavanged from the Petter parts tray you could creat a real self adjusting valve train ( no more tick ) and what leakage there was would lubricate the valve stems and cam lobes.

On the other hand you could just buy a big 120-120 Petter 10-1 @ 1000 rpm and set your vavles every 1000 hours as recomended.......

Doug

bitsnpieces1

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Re: Roller rockers
« Reply #122 on: August 11, 2006, 03:02:57 AM »
Yeah you can't have it a sealed system, expansion from temp changes will split things apart.  Hydraulic lifters in engines have a bleed off port and are refreshed with oil from the oil gallery all the time.  Keeps the oil flushed out, adds volume as things wear down.  All you would need to do is take the top off the hydraulic lifter off, stick in a pipe to bring pressure up to valve, then put top of lifter back on the end of the pipe and have it push against the valve.  THEN you have to have a continuous supply of oil at about 30 psi.  Means an oil pump like a car has ( OR a small motorcyle).  
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).

fattywagonman

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Re: Roller rockers
« Reply #123 on: August 11, 2006, 02:38:43 PM »
BTW it was Andre not Guy who proposed the oil operated valve train... which is a tried and tru method of valve operation and is almost always used in large engines like this... http://people.bath.ac.uk/ccsshb/12cyl/ notice the pipes going to the top of the heads..

bitsnpieces1

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Re: Roller rockers
« Reply #124 on: August 11, 2006, 05:29:41 PM »
AH HAH,  So is the small pipe just to the left of the head the line to the injector itself? 

Just do the same thing, MMM, wonder what the tolerances will have to be when you go smaller. 
« Last Edit: August 11, 2006, 05:31:36 PM by bitsnpieces1 »
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).

Andre Blanchard

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Re: Roller rockers
« Reply #125 on: August 11, 2006, 05:57:32 PM »
AH HAH,  So is the small pipe just to the left of the head the line to the injector itself? 

Just do the same thing, MMM, wonder what the tolerances will have to be when you go smaller. 

Thinking a little more on this.
How much does the injector pump for a 6/1 cost?
Could use them on the lower end with just some slave cylinders at the top.
Bonus is you would then have control of how long the valve stayed open.
______________
Andre' B

bitsnpieces1

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Re: Roller rockers
« Reply #126 on: August 11, 2006, 06:28:59 PM »
Lets see;  the hydraulic lifter uses a pumpup port similar to the bleedoff part of the injection pump.  Could just plumb a small reservoir of oil to the IP port, ?feed-return?, line.  That would take care of the oil expansion problem.  Adjust just like my old Chevy.  Loosen up until valve starts clattering, then slowly tighten until noise stops, then tighten a specified amount more. Usually 1/4 to 3/4 of a turn.  That puts the piston in the center of travel and gives room to both sides for expansion/contraction.  Eliminates need for readjustment, eliminates a lot of valve noise, should eliminate a certain amount of wear, and takes care of the misalignment problem.  Might use some type of bellows arangement at the valve itself.  Would solve leakage problems at that end.

  Andre, I think you've hit on a real good one. 

AND eliminates need for another continuous flow oil pump. 
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).