93reefblue347AFR

I was woundering how much pre-load is to much. I thought that you want to pre-load about 1/4 to 1/2 up to 3/4 a turn after finding zero lash, but today I was talking to crane cams tech and he said that they have done dyno test that show you make more power and you can rev. higher with 1 full turn even up to 1 and 1/2. I thought that was way to much but what he said made sence, he said that all your doing is making that valvetrain lighter with less oil in the lifter and if there is oil in the lifter then it will always work fine. I forgot how many thousandths of travel he said is in a hyd. roller lifter but the 1 full turn= to 40 thousandths pre-load left plunty of room befor bottoming out the lifter. So I wanted to ask you opinion on it all.

mjr46

honestly I wouldn't trust any of the crane cam techs.....7 dollar an hour self educated on the computer screen.......1/4 to 1/2 is what any article will tell you and that's what I've always done with no ill effects

AdderMk2

i ran 3/4-1 turn on my motor at first... 3 bent pushrods later, and I run 1/4-1/2 turn now

67mustang302

The amount of power saved and rpm gained from the lesser amount of oil that a whopping .020" more preload will result in is prolly so small you couldn't find it on a dyno. As long as you have enough preload that there isn't clearance, but not so much that you jam up the valvetrain, you're good. You're better going on the small side of the preload to allow yourself a margin of safety for lifter compression or heat expansion.

93reefblue347AFR

Yea thats what I have always done, The most I have done is 3/4 but I always run 1/2. But there is a big thing on there web sit that talks about it making more power going 1 to 1 and 1/2 turns in. I'm not going to do it but this time i think im going to run 3/4. I was thinking about it last night also, when you check for push rod lengthand you convert you hyd. roller into a solid if you do it that way you have to grind like 20 thousandths off of you lifter piston to = 1/2 turns of pre-load and if you wanted to run 1 and 1/2 turns in you would have to grind off 60 thousandths to = you 1 and 1/2 turns of pre-load, that means you would have a longer push rod and you would think that would be heavier than the oil that you wouldnt be useing. Tell me if im wrong.