Tom,
I know what you are going thru. I spent quite a bit of time trying to
adjust the hydraulic valves on my Z28's 350 until I read the instructions
VERY carefully. But this might help. If you go to the Chevelle Tech page
at http://www.chevelles.com/techref/ftecref17.html there is some good
detail as to how to adjust your valves. These are for setting valve
adjustment with the engine off (on an engine stand is really nice). The
hardest part is knowing "loose" and "tight", or when is the valve "just
starting to open". I found that if I tighten the rocker to "spec" then
rotate the engine I could spin the push rod. So I tightened it some more
and after rotating the engine, I could spin the push rod. I thought that
the push rod would be too tight to turn after adjusting the valve....NOT
SO!!
After rotating the engine to get the correct valve in position, loosen the
rocker so there is obvious clearance between the valve stem and the rocker.
Then use a 0.002" feeler guage to set the initial starting point. Then
tighten the recommended number of turns. My failure to properly know what
my initial starting point was created a nightmare, resulting in adjusting
the valve lash 3 times.
By the way, I installed a Edelbrock cam and it gave slightly different
instructions than Chilton's. Their recommendation is to adjust the exhaust
valve just after (or is it before?) the exhaust valve opens and the intake
just before it was to open (or close). If interested, I can look these up
to get them correct. The purpose of this slight difference in positioning
was to accomodate non-symmetrical cams.
By the way, there is a lot of good technical reference info at
http://www.chevelles.com/techref/ and you may want to look around the rest
of the site. It has lots of "older" Chevy engine information.
Jon '53 3100 w/ '68 Chevelle 327
jelerath@us.ibm.com
Thomas M OBrien <tmobrien@juno.com>@autox.team.net on 01/30/2000 10:14:58
PM
Please respond to Thomas M OBrien <tmobrien@juno.com>
Sent by: owner-oletrucks@autox.team.net
To: oletrucks@autox.team.net
cc: 60schevy@topica.com
Subject: [oletrucks] valve adjust
At the risk of sounding "mechanically challenged", I adjusted the valves
on my newly broken in 283 this weekend according to the specs in the
Motors Manual and Shop Manual and now my truck wont start. The starter
will crank the motor and makes a whining sound that wasn't there before,
and then a puff of air out the exhaust.
I warmed up the engine, turned the crank to # 1 TDC, and adjusted
appropriate valves; then cranked over to # 6 TDC and adjusted the rest.
Checked distributor to double check rotor in correct firing position.
Rolled pushrods between fingers to take out lash then turned 1/2 turn
down.
Is it normal to have to turn down the adjusting nuts a lot after just
breaking in a new rebuilt motor - like around 4 turns or more? Am I
missing something? Did I screw up the timing so it wont fire at the
right moment? Is it possible to turn down the adjusting nuts too far?
Interference between piston and valve?
Thanks for your help. Gotta love these old 283s.
Tom O.
60 Apache K20.
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|