<VV> Re: rockers

[BBRT]

Get rockers from a vendor. If you are worried about high lift and the rocker 
stud slot, check a standard old one for that. Set your valve stem tip and 
rocker tip pad so that the contact patch is in the center of the stem when 
at half lift. Generally, if you have the heads flycut to get a good gasket 
surface, that removal of head material will compensate for a reground cam 
(smaller base circle diameter) and you can use stock length push rods. (As 
you move the head closer to the cam, because you milled the gasket surface, 
the pushrod now pushes the rocker up and you effectively move the rocker up 
so the tip on the other end of the rocker starts closer to the stud (unless 
I have it backwards)..Therefore the up and down motion of the rocker tip now 
has an arc across the stem face which is closer to the stud.  However, a 
reground cam is smaller so the lifter and pushrod are father away from the 
head-which effectively brings the pushrod end of the rocker back down about 
to where it is stock, more or less.) You can generally use stock pushrods 
for most applications and still be in the acceptable range of rocker tip 
movement over the end of the stem. Now a NEW cam on a new cam core that has 
a stock base circle combined with severely cut high compression heads will 
result in a much closer distance between the head and the cam which means 
you MUST compensate with different push rod lengths for proper 
geometry-roller rockers or otherwise.

Chuck S
BBRT

----- Original Message ----- 
From: <djtcz at comcast.net>
To: <virtualvairs at corvair.org>
Sent: Sunday, October 16, 2005 8:43 AM
Subject: <VV> Re: rockers


> snipped and bottom posted
> -------------- Original message -------------- 
>
> Original message
> Subject: <VV> Rocker Arms
> snip--------
> ---------- Third, I would appreciate a consensus of what works.  I know of 
> the roller rockers from Ray S and the originals rockers.  I will be 
> building my first
> Corvair engine by myself soon and I would like to know which replacement 
> parts
> have the seal of approval. I will not, however, under any circumstances 
> use SBC
> rockers, unless someone can convince me I am misguided.  The rest of the
> argument, I just can't understand and I think there must be others who 
> don't
> rebuild engines on a regular basis who would love to know the answers to 
> these
> things.
>
>
> Ron Byers
> Largo, FL
>
> ===============================
> If my get-another-Corvair urges kick in a little harder I expect I'll have 
> to play some reindeer games and check that the rocker tips bear at the 
> center of the valve tip, or at least does not get too close to the stem's 
> edge at zero and full lift for my exact combination of cylinder, head, and 
> gasket .  Oh, and also that rocker slot does not reach the stud at full or 
> zero lift.  If the arm and ratio are approximately right, I expect 
> monkeying with push rod length will probably achieve good operating 
> geometry.  Some would say those checks are part of good thoughtful engine 
> assembly anyway.
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