How does varying the hydraulic lifter preload affect engine performance? In some manuals I see that the setting should be 1 turn of adjusting nut after all freeplay has been removed and some posts have said to go only 1/4 after taking up freeplay. Wouldn't the larger preload keep adjustment longer?

 

Different preload will not affect engine performance as long as you are 'in the range' of travel of the lifter internal piston and do not have rocker arm clatter and are not holding the valve off the seat. There was talk years ago about lifters pumping up at higher RPM, and you would have less pump-up effect if you were towards the 'looser' end of the adjustment, but in normal driving, there should be no difference. The cam will lift the lifter, push the pushrod, rock the rocker arm and open the valve just the same... loose or tight... as long as it is not bottomed or clacky.

tom

 

Thanks for the explanation.

 

Yea, Tom is right. As long as your in the ballpark, the lifter will "pump up" as it were to take any unneccessary clearance out of the system. That's the whole point of hydralic lifters. You can go down another half turn if you want to, as long as there's still room for the plunger to move, and it will run the same. Don't go too far or the natural "pump up" could cause problems adter all. The stock setting is best.

 

 

just tight enough so there is no noise is the best setting...:-X12

 

>just tight enough so there is no noise is the best
>setting..

I agree with engineguy. The only thing is, if you plan to leave the valve covers on for 50-100K miles I would tighten it up a little to help prevent clatter down the road when everything starts to wear.

86 F250 4x4,4.10 gears,4 speed, 10.25 rear, dana 50, 460, weiand stealth, edelbrock 750, heddman headers, 36" super swampers

 

i like mine at 1/4 turn after contact.seems to me the engine rev's more easily.definately no more than 1/2 turn,different brands of lifters are a little different as to their preload range.i would expect at 1 turn the plunger to be dangerously close if not already bottomed out.if setting the preload w/the engine running i don't like all that pressure on the lobes during the turning.

 

FYI

A Ford hyd. lifter has .175" of travel, and a 3/8-24 stud moves .042"
per revolution.

 

I'm wondering about the actuall adjustment procedure. There aren't two nuts on a stud in the rockers on the 90 F-250 (5.8L) engine I'm working on. Just a bolt. If I just tighten that bolt down the extra 1/2 to 1 turn once the pushrod starts to feel friction, is the bolt going to stay in position? It doesn't look like there was any loctite in there before, so I wasn't going to put any in there. Am I just not seeing a locking mechanism? I'm worried that any adjustment is going to just back right out.

I'm replacing the head due to some burnt valves, but reusing the stock lifters and rockers and pushrods.

Thanks in advance.

 

I believe on those heads that you tighten it down till it bottoms, then tighten 15-20 ft lbs. Check the manual to be sure.

86 F250 4x4,4.10 gears,4 speed, 10.25 rear, dana 50, 460, weiand stealth, edelbrock 750, heddman headers, 36" super swampers