Roller lifter preload

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Jerry Miller

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I have an 89 roller cam motor. I’m getting .125” of lifter preload on the new build. The new lifters have over .200” inches of travel so I’m in the middle. I know the magnum engines run .120 or so I’ve heard but is this okay with the LA 360 considering the lifter range?
Jerry
 
Not sure. On my big block stuff I shoot for anywhere between 60-100 thou.

Where can I find this info regarding .120 preload on magnum engines as I also have one of those too and may soon change to roller tip rockers?
 
Roller lifters usually require more preload than flat tappets. That said, I'm nervous running heavy preload on most anything. I consider .125" heavy preload. They may well work best there, but I'm hard headed and would not do it.
 
I shoot for .060-.090 on magnum stuff. And the roller LA uses the same lifter If I’m not mistaken.
 
4mulas said:
Not sure. On my big block stuff I shoot for anywhere between 60-100 thou.

Where can I find this info regarding .120 preload on magnum engines as I also have one of those too and may soon change to roller tip rockers?
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Hughes cams has it on their site.
 
TT5.9mag said:
I shoot for .060-.090 on magnum stuff. And the roller LA uses the same lifter If I’m not mistaken.
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They can use the same lifter but there are magnum specific ones too from what I found.
With non-primed lifters at TDC I have .125” of preload and then I can take my thumb on the rocker arm and compress the lifter another .095 to .105” so I’m right in the middle of the lifters’ range I just wonder if shimming the rocker shaft is worth it since it will mess with the geometry ever so slightly. Honestly I’m over this build. It’s my son’s truck and he’s a teenager. Do I need to say more LOL
 
Dial indicator on top of rocker arm right at the pushrod. I started with the rocker shaft tight and slowly unbolted. I also reversed this and checked it as I tightened it. Engine at TDC compression stroke.
 
I think it was Shakespeare who said 'A lot of ado about nothing'.....

Run your lifters anywhere in the range that the collapsed lifter has. If the prod seat can be pushed down 0.200" until it bottoms, then your pre-load range is 0-0.200", but you should not go to either extreme, so a safe range would be 0.010" to 0.190".
 
Bewy said:
I think it was Shakespeare who said 'A lot of ado about nothing'.....

Run your lifters anywhere in the range that the collapsed lifter has. If the prod seat can be pushed down 0.200" until it bottoms, then your pre-load range is 0-0.200", but you should not go to either extreme, so a safe range would be 0.010" to 0.190".
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Much ado about nothing!
 
Jerry Miller said:
Dial indicator on top of rocker arm right at the pushrod. I started with the rocker shaft tight and slowly unbolted. I also reversed this and checked it as I tightened it. Engine at TDC compression stroke.
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What kind of rocker arms?
 
Jerry Miller said:
Stock stamped steel ones. 1.5:1 ratio. Based on the responses, sounds like my original gut feeling of just running it unshimmed will be just fine. Thanks all.
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If you really needed to reduce the preload (which I don't think you do) the proper way would be to get shorter pushrods, not rocker shaft shims.
 
MopaR&D said:
If you really needed to reduce the preload (which I don't think you do) the proper way would be to get shorter pushrods, not rocker shaft shims.
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Thanks. I agree. I’m just going to run it.I agree shimming would be a bandaid fix.
Jerry
 
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