This is a discussion on Lifter Pre-load within the Internal Engine forums, part of the LSx Technical Help Section category; Ok, so im kinda confused about how to set the pre-load on my new lifters when installing my cam...? I'm ...
01-16-2009, 08:43 AM #1
Ok, so im kinda confused about how to set the pre-load on my new lifters when installing my cam...? I'm using Comp 850's, and they recommend installing the lifters, pushrods, and rockers and torquing them to spec in sequence, then rotating the engine until (#1 cylinder) both the intake and exhaust valves open and close (for lifter bleed down). I'm guessing you set it to TDC...? Mark a reference on the pushrod. Loosen the rocker bolts so there is no pressure on the lifters, then mark the 2nd reference and the distance between is the pre-load (should be between .020"-.040").
The guys at Texas-Speed told me that for most cases, they use .040" preload and this is how they told me they set pre-load... Torque everything down to spec with the #1 piston at TDC. Then angle torque the bolts to .040" preload (they told me every 90 degress is .014" preload, but it scares me having to stretch each of those bolts around 270 degrees.) Is that a safe way to do it or does anyone else have other opinions?
01-16-2009, 09:27 AM #2
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Depends on the lifter how much pre-load you want on them.
OEM lifters like .80-1.0 of pre-load.
Morels like .25-.30 of preload.
01-16-2009, 02:30 PM #3
01-16-2009, 04:00 PM #4
Sounds like you're not using adjustable rocker arms... If not, you can't set the preload.
With the 850's, you should just tighten them down & be OK. The 875's are more critical for adjustment.
At TDC, take the rocker bolt down till there's no pushrod lash, then see how many turns till it tightens up. I'd say if you're more than 1.25 full turns, you need shorter pushrods, or new adjustable rockers.
01-16-2009, 04:05 PM #5
I actually shimmed up my hole rocker assembly's to get 1/4 to 1/2 turns till tight...
01-16-2009, 04:46 PM #6
01-16-2009, 04:58 PM #7
01-16-2009, 04:59 PM #8
.020 - .040 is a 1/4 to 1/2 turn on adjustable rockers.
01-16-2009, 05:03 PM #9
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