Date: Wed, 30 Aug 2000 23:07:42 EDT
Reply-To: Wolfvan88@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Robert Lilley <Wolfvan88@AOL.COM>
Subject: Re: Thinking about adding Ratio rockers
Content-Type: text/plain; charset="US-ASCII"
Mark,
Rhino rockers use a 9 mm valve adjusting screw.
The Rhino Feet are 9 mm and the whole head swivels (patterned after the 911
Porsche style) RATHER than the 8 mm swivel tips screws that have a head with
a ball that has a flat spot and the ball swivels.
The 1.25 rockers at FGA are most likely 8 mm shaft screws unless they say
other wise.
Stock VW WBX rockers are 10 mm screws.
The Berg style is the slider type. Rather than the screw sliding on the
valve tip the face of the rocker arm slides on the valve tip. They have are
offset so the side load is decreased with the increased lift.
The Pauter roller tip rolls on the valve tip, this style eliminates more side
load than the slider method Berg employs.
When one increases the lift of the valve, the valve train must work harder to
move that weight further. The stock valve springs were designed to move X
amount of weight Y distance. Add ratio rockers and the weight is multiplied
by adding Y + Z (being the increased lift) The stock springs are now being
asked to push the same weight further.
In valve train design, you want to reduce the weight that the springs have
to move OR increase spring pressure to be able to move the same weight
better, to control valve float (This is where the springs can not close the
valve fast enough and it stays open)
There are several methods to doing this.
1 Decrease valve weight: stainless steel, titanium
2 Decrease push rod weight Cromoly
3 Decrease retainer weight Cromoly, titanium
4 Decrease rocker weight aluminum alloy
5 Decrease the weight on the valve side of the rocker
Depending on what the budget and design of the engine: HP, RPM limit
determines the components of the valve train.
If you increase spring pressure, you shorten the life of the lifters and cam.
VW determined the pressure to control the valves and live a long life, I did
not want to increase the pressure so I opted to lighten the weight the stock
springs have to push to control the valves at higher RPMs.
The Berg method of putting the screw on the side opposite of the valve tip
helps to reduce reciprocating weight, but they rockers are still made from
forged steel: Heavy.
To further reduce this reciprocating weight, Pauters rockers are made out of
a lightweight aluminum alloy with a roller tip. This also reduces side load
on the valve stem.
When I put together my engine, I used the stock springs and lightweight
Cromoly push rods. They weighed a fraction of the weight the stock steel
weighed AND are stronger and are more resistant to flexing then the stock
steel. I also used Cromoly spring retainers along with racing valve locks to
further lighten weight. I used the 9 mm 1.25 ratio rockers with the 911
style rhino swivel feet to reduce side load on the valve. I also utilized a
solid rocker shaft to eliminate the spring clips that can break.
Had I seen the Pauter roller rockers one year ago, I would have used them to
further reduce the reciprocating weight and plus the above added benefits.
They are also cheaper than the Berg rockers.
When you reduce the reciprocating weight, you "effectively" increase the
valve spring pressure. By this I mean that there is less weight for the
spring to push so it can control the valve better AS IF it were a heavier
spring, BUT you do not have the wear of a heavier spring.
If I were going with ratio rockers today I would seriously look into and most
likely buy the Pauter roller tip rockers for a bulletproof valve train.
Robert
