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Is this caused by too much lifter preload?

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Old Dec 20, 2004 | 10:02 PM
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Default Is this caused by too much lifter preload?

From the ripples in the top of my power curve I't seem's I'm getting valve float from my dyno gragh right before 6K RPM, I was expecting my power to peak around 6.2K RPM before this would happen. I have a TR224 cam,Comp R lifter's that I know are not the best for my combo,TR 7.4 Inch push rods,stock rockers,and stock out of the box 205 AFR heads. I'm thinking I have too much preload on the lifters and the valves may be hanging open.What do you all think? Too much preload on the lifers? Do you think ajustable rockers would be the fix. Thanx in advance.
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Old Dec 20, 2004 | 10:13 PM
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Which 224 cam is it. The .551/.563/.581 lift version? What type of springs? Did you check the pre-load on the lifters? If you just installed the stock rockers at there normal setting, then there is deffinatlly to much pre-load. I would go to Lowe's or Home depot and get you some 5/16 or 8mm flat washers that are about .045" thick and place them under the rocker shaft. That will relieve alot of the pre-load, but you should deffinatlly check it. Place your #1 piston at TDC, tighten the rocker bolt until all play is removed between the pushrod and lifter, then see how far around it is until 22 ft lbs. I would want about a 1/4 turn at most on those lifters. You can play around with diffrent washer thicknesses to get the load where you want it.
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Old Dec 20, 2004 | 10:32 PM
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Originally Posted by Beast96Z
Which 224 cam is it. The .551/.563/.581 lift version? What type of springs? Did you check the pre-load on the lifters? If you just installed the stock rockers at there normal setting, then there is deffinatlly to much pre-load. I would go to Lowe's or Home depot and get you some 5/16 or 8mm flat washers that are about .045" thick and place them under the rocker shaft. That will relieve alot of the pre-load, but you should deffinatlly check it. Place your #1 piston at TDC, tighten the rocker bolt until all play is removed between the pushrod and lifter, then see how far around it is until 22 ft lbs. I would want about a 1/4 turn at most on those lifters. You can play around with diffrent washer thicknesses to get the load where you want it.
The cam is a TR 224 with a .562 of an inch lift, I was told by AFR that the springs are most likley Patriot golds, I'm not shure how much preload I used, I just put in comp R's in and tighend down the stock rockers. I was told the comp R's would work. Thanx for the info, I'm gonna try shiming my stock rockers.I really hope I didn't slightly ding my pistons because I have reved past 6.5K RPM.

Last edited by Oatmeal; Dec 20, 2004 at 10:49 PM.
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Old Dec 20, 2004 | 11:50 PM
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Be sure and check the thickness of the shims. The washers I used varied a bit in thickness, so I had to carry my caliper to the store with me to get 16 that were within a few thousandths of each other.
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Old Dec 21, 2004 | 06:44 AM
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Just get comp pro magnum rockers..adjust preload .008-.010 (1/5turn) like its supposed to be done...clearance your valvecovers...check the pushrod length...do it right and dont guess.
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Old Dec 21, 2004 | 07:54 AM
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Not enough spring rate does the same thing

Dave
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Old Dec 21, 2004 | 07:59 AM
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Originally Posted by SAM98WS6
Just get comp pro magnum rockers..adjust preload .008-.010 (1/5turn) like its supposed to be done...clearance your valvecovers...check the pushrod length...do it right and dont guess.
You need adjustable rockers with comp Rs

Brad
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Old Dec 21, 2004 | 08:00 AM
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Originally Posted by 99Fbody99
Not enough spring rate does the same thing

Dave
Dave,

he has plenty of spring for that cam.

Brad
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Old Dec 21, 2004 | 06:11 PM
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Thanx guy's.
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Old Dec 21, 2004 | 07:12 PM
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I am under the impression that it does not matter on the ls1 for you to set pre load that is why the engine hydralic stuff.....But I am not possitive. I was also under that you had to use rockers with the comp r's to make them work
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