Setting Valve Lash/preload On Tfs Heads.......1/2,3/4, Or 1 Full Turn

[BKM48198]

I have read that to set preload on stud mount rockers you set at zero lash and then go 1/2 , 3/4, or a full turn. I am wondering which is better and why, what are the pros and cons of one over the others? I have a stock bottom end and just put a set of TFS 170 heads and a TFS Stage 1 cam, I went with the 1/2 turn and it runs good but I'm wondering if that was enough or if it really should have another 1/4 to 1/2 turn of preload.

 

[Grn92LX]

1/4-1/2 turn is fine.

 

[Gearbanger 101]

I've ialways gone 3/4-1 full turn. You may not "need" to go that much to attain the correct preload, but the consiquence if you don't have enough preload on the lifter is a noisy valve train and potentially prematurely worn parts.

If memory serves, you want to try for .030-.040 preload on your lifter. The lifters are good for about .060 before they bottom out.

Also keep in mind, if they've been used (i.e. are full of oil) the probably won't collapse right away and will likely start opening the valve as you tighten them down....giving you the impression that they've bottomed out. Don't pay any attention. As long as you're under one full turn and after everything settled the centre of the rollers line up with the middle of the valve, you'll be alright.

 

[BKM48198]

1/4-1/2 turn is fine.

I am wondering which is better and why, what are the pros and cons of one over the others?

 

[BKM48198]

I've ialways gone 3/4-1 full turn. You may not "need" to go that much to attain the correct preload, but the consiquence if you don't have enough preload on the lifter is a noisy valve train and potentially prematurely worn parts.

If memory serves, you want to try for .030-.040 preload on your lifter. The lifters are good for about .060 before they bottom out.

Also keep in mind, if they've been used (i.e. are full of oil) the probably won't collapse right away and will likely start opening the valve as you tighten them down....giving you the impression that they've bottomed out. Don't pay any attention. As long as you're under one full turn and after everything settled the centre of the rollers line up with the middle of the valve, you'll be alright.

I did 1 full turn on the pedestal mount rockers on my old set of GT40 heads and only 1/2 turn on the TFS heads.....I asked TFS and they said 1/2 turn was what they recommended but didn't atually answer my question of the pros and cons of the different amount of turns, and I'm really not sure of how to actually physically measure the amount of pre-load and set them at the .030-.040 setting. The engine runs fine now but I really want to set them as close to perfect as I can, I'd rather not have to pull the upper plenum to re-adjust the preload but don't want to lose any power I might be able to gain.

 

[dcurtis]

I always run at least 3/4 turn, my new engine revs well above 6500 now so I go 1 full turn