lifter preload????? - Team Camaro Tech
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post #1 of 4 (permalink) Old Jan 10th, 00, 07:26 AM Thread Starter
Join Date: Dec 1999
Location: arnold, mo, us
Posts: 26

OK guys. I have adjusted my valves every different way I can think of, and I can't decide how much preload is best. I have one person telling me 1/4 past zero, and another saying a full turn. Now this is a stock motor, with full roller rockers. I am going to be buying a new vortec 350 crate engine, and changing the stock-stamped rockers for some self aligning roller tipped rockers. Most books I've read say 3/4 turn or a full turn. I need some opinions on this subject. I know the more preload the less lift there is at the valve. Is 1/4 turn not enough? I don't want to have to adjust my valves every 6 months or even every year. I also don't want to tight of an adjustment... Thanks guys
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post #2 of 4 (permalink) Old Jan 10th, 00, 02:03 PM
Join Date: Aug 1998
Location: Waldorf Md. USA
Posts: 3,278

The factory spec is 1 turn. If you plan on turning the motor very high rpm, it is best to stay as close to "0" lash as possible, maybe 1/8 turn. The reason for this is if the lifters start to "pump up" at high rpm's they can only hold the valves open a slight bit. Your 1/4 turn is a good compromise and will work fine 90% of the time. If you dont plan to really rev the motor than tighten it up anothe 1/4 turn and you should never have to touch them.
Hope this helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

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post #3 of 4 (permalink) Old Jan 11th, 00, 05:25 AM
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Join Date: Aug 1999
Location: Spokane, WA.
Posts: 522
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I know that the specs call for 1/4 to 1/2 past zero. Is that just for a stock motor? I also know that on my motor (327 .030 over, Edelbrock Performer RPM heads-cam-intake-750 cfm carb, gear drive, crane roller tipped rockers) If I try to go past zero lash the engine will not start (no compression because the valves have started to open) I adjusted the rockers so the push rod just starts to turn. Its the only way it will run, 1/4 past and it turns the motor with no compression. Yes they are hydrolic lifters, not mechanical or rollers.
Also my timing is about 24-26 degrees btdc According to my harmonic balancer, mark points straight upand at least an inch from the timing tab. Ignition is a stock points type distributer converted to electronic with Cranes XR700 conversion kit, Crane HI 6 Capacitive discharge module and the PS-91 coil. Crane Fire wires and Autolite spark plugs.
Now if I remember correctly the book that I got with the heads and the cam did mention that lifter preload was not required. Any thoughts or comments about either would be welcome. Is it possible that I have the wrong Balancer? The gear drive is of course Edelbrock Accu-Drive and is "noisey" Sounds great!!!

67 ss/rs, MODIFIED
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post #4 of 4 (permalink) Old Jan 11th, 00, 11:20 AM
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Join Date: Aug 1999
Posts: 70

I always go 1/4 turn past 0. Make sure cam lobe is on the bottom of the base circle when you do this to do it right, and you will not have a problem with valves starting to open. If you want more info on adjusting the valves, email me.

66/70 chevelle ss396's
69/71 camaros
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