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<DIV><FONT face="Palatino Linotype" color=#000080 size=4>You're RIGHT about that
LC2 stuff. I've been reading too many back-issues of <U><EM>GM High-Tech
Performance</EM></U> without mentally correcting for the 3800-series heads they
(i.e., PAS) slapped on the Grand National LC2s for the Turbo Trans Am
application. <EM>Those</EM> heads took Corvette-type self-centering
roller-rockers (I used Cranes... pedestals, no shafts) with what I remember was
somewhat shorter pushrods (which I always get from Crower). Maybe I'll try
to locate some of those spares (had to buy a full set of 16) and see if I can't
make 'em work. I've never had those valve-covers off since I bought the Sy
or the Ty.</FONT></DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT> </DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4>For your well-deserved
reward, I'll now pass on an arcane design tip for custom-engine builders (as I
used to be): When converting to Rollers, get a test-pushrod and
weak-spring to mount the valve/retainer. Vary the length of that 'rod
keeping 2 key rules in mind to ensure reliability and high-RPM
stability:</FONT></DIV>
<OL>
<LI><FONT face="Palatino Linotype" color=#000080 size=4>Keep the Rocker Arm as
"low" as possible... as close to the basenut or pedestal base as possible
without any part of the Arm touching it... to avoid galling, AND</FONT>
<LI><FONT face="Palatino Linotype" color=#000080 size=4>At 40% of the total
valve lift off its seat, the centerline of the roller-tip should be directly
over the exact middle of the face of the valve tip (or lash-cap, if you use
those).</FONT></LI></OL>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4>When both of those
conditions are met, you have your perfect length for your pushrod. True
purists and the ultra-fastidious, who don't trust replicated head geometry
throughout both heads, would want to repeat this exercise for each
rocker/valve/pushrod combination and then generate a screwball order for up to
12 different pushrods. Good luck trying to keep all the matched-set
markings straight!</FONT></DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT> </DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4>Yes, yes, we all know
about roller-rockers affording lower levels of friction and pumping losses, but
they <EM>really</EM> come into their own by bestowing longevity to the integrity
of your valve guides and their seals. By <EM>rolling</EM> over the valve
tips instead of sliding/grinding over the same, they virtually eliminate that
ferocious side-loading of the valve stem which gradually turns those nice, tight
cylindrical guide passages into nasty, OVAL'd holes which can get bad enough to
cause the whole valve to rattle and wobble as it tries to seat/bounce under
spring pressure! How I wish I had converted back in '98 when I bought that
Syclone! My seals would still be holding all that oil in the top of the
cylinder heads instead of being sucked down into the ovaled-out
intakes....</FONT></DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT> </DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4>Gotta go,</FONT></DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT> </DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4>D.O.
<HR>
</FONT></DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT> </DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT> </DIV>
<DIV style="FONT: 10pt arial">----- Original Message -----
<DIV style="BACKGROUND: #e4e4e4; font-color: black"><B>From:</B> <A
title=sytydave@gmail.com href="mailto:sytydave@gmail.com">Dave Goodhue</A>
</DIV>
<DIV><B>To:</B> <A title=Syty@syty.org
href="mailto:Syty@syty.org">Syty@syty.org</A> </DIV>
<DIV><B>Sent:</B> Friday, June 15, 2007 6:59 AM</DIV>
<DIV><B>Subject:</B> [Syty] Roller Rockers...</DIV></DIV>
<DIV><FONT face="Palatino Linotype" color=#000080 size=4></FONT><FONT
face="Palatino Linotype" color=#000080 size=4></FONT><BR></DIV>>What
model/brand?<BR><BR>>I think 3.8L Buick (LC2 engine) uses the same valve gear
as the Chevy<BR>350 and the 4.3L >Vortec uses Chevy 305 gear... or is it the
other way<BR>around?<BR><BR>The Buick LC2 has shaft mounted rockers.
The 4.3 is similliar to the<BR>305/350 (305 is just a small bore
350) The 4.3 is basically a 3/4<BR>350, sharing the same bore and
stoke. (Tidbit of info, the 229 V6<BR>Chevy is an 3/4 oddfire
305.)<BR><BR>Anyway I used a Crane Gold narrow body rockers and they worked
just<BR>fine, clear the valve covers fine. As for Vortecs, typically
the<BR>lower intake needs to be modifed (extended to cover the longer
ports)<BR>and the heads will need to be redilled as the intake bolts have
a<BR>different pattern. Vortec also have metric screw in studs, while
most<BR>SBC aftermarket rocker are based on english threads. The
easiest<BR>solution is have the head redrilled and tapped for the english
thread,<BR>so you can use common SBC studs and
rockers.<BR>_______________________________________________<BR>Syty mailing
list<BR><A href="mailto:Syty@syty.org">Syty@syty.org</A><BR><A
href="http://lists.syty.org/mailman/listinfo/syty">http://lists.syty.org/mailman/listinfo/syty</A><BR></BODY></HTML>