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| | | | Joined: Mar 2011 Posts: 153 'Bolter | | 'Bolter Joined: Mar 2011 Posts: 153 | I'm sure this has been discussed many times but once more please. I have a rebuilt 58/59 Chevy 235 that came with hydraulic lifters. My 41 through 56 shop manuals only deal with adjusting valves with solid lifters. Tightening the rocker arm adjusting screws (engine not running)beyond the point of contact with the valve stem led to zero compression on my compression tester. It would seem to me that additional pressure should compress the lifter, not hold the valve open. I'm only talking 3/4 of a turn here. This is a freshly rebuilt engine ready for its first coaxing to life. I got it to run today briefly but only 90-100psi per cylinder. That seems anemic to me for a fresh rebuild and I suspect the valves. Feedback anyone?
1946 Chevy pickup, 1948 Chevy suburban, 1950 Chevy pickup, 1952 GMC pickup, 1957 Chevy pickup, 1939 Chevy pickup
| | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | With cold oil it takes quite a while for the lifters to bleed down to running position. For that period the engine will have low to no compression.
Also, give every thing a chance to break in before worrying about the compression.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Feb 2004 Posts: 29,875 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,875 | You need to be sure the valves are completely closed before making the preload adjustment. It will take several minutes for the lifter to bleed down to a fully-adjusted position. I like to use what's called the "companion cylinder" adjustment method, where the cylinder that's between exhaust and intake provides the position reference for the one that's halfway around the firing order, on TDC compression. I've explained it several times, so an archive search for "companion cylinder" should locate one of the threads. I consider it to be the most accurate way to adjust all valves, solid lifter or hydraulic.
Jerry
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| | | | | Joined: Mar 2011 Posts: 153 'Bolter | | 'Bolter Joined: Mar 2011 Posts: 153 | Well, the oil is plenty cold. I'm clearly being impatient here at the startup phase which is ironic given that this engine has been sitting in the garage for over 8 years waiting for the restoration to get to this point! I'll definitely check out "companion cylinder". I will run it a while before checking compression again. It occured to me that the rings haven't seated yet either. By the way, what kind of compression numbers should I be looking for when broken in? Thanks for the advice guys! Dave
1946 Chevy pickup, 1948 Chevy suburban, 1950 Chevy pickup, 1952 GMC pickup, 1957 Chevy pickup, 1939 Chevy pickup
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