Roller rocker adjustment?
Ok so here's the problem I'm haveing has anyone heard of it? My build is a 96 f150 5.0 4wd. (4r70w auto just rebuilt and strengthened) gt40 ringed heads trickflow springs w/dampeners scorpion roller rocker 1.6 ratio and comp cam hi-tec hardened push rods. Comp cam extreme energy 35-510-8 hydroelectric roller cam, Bored 30 over with hypereutectic pistons all new lower end barrings, hardened oil pump shaft, idol air adjuster, k&n cold air intake so the problem is that after setting my rockers for the first time, the process I used was starting with the exhaust compressed on cylinder one I tightened the intake to 0 lash (where the push rod just barely quit moving) then turned it 1/2 turn tighter, tightend the polilock and then did exhaust. Continuing to turn the crank as I did all the others. They felt quite tight about 18lbs of pressure to accomplish the 1/2 turn. After everything was installed I had 0 compression indicating to me that the valves were hanging open so I backed the rockers of 1/4 turn this accomplished 60lbs of compression indicating I was going in the right direction. Next I backed them all off to lose and follow the proper sequence of adjustment I tightened them to 0 lash with no preload turn at all, tightened the polilock and tested again. This time I accomplished 120lbs of pressure. My question is has anyone heard of this problem and should I just run it like this?

 

Working on one cylinder at a time, watch the intake pushrod while rotating the engine in the normal direction of
rotation. When the pushrod moves up and then all the way down (intake valve just closes) install the exhaust
rocker. Make sure the radius on the pedestal mates with the radius on the rocker fulcrum - the flat on the
fulcrum goes up against the head of the attaching screw. Lube with Scorpion Cam & Lifter Installation
Lubricant (part numbers SRPAL4-1 or SRPAL8-1) and lightly snug the rocker arm attaching screw with your
fingers until the up and down looseness of the rocker is taken up (zero lash). Setting your torque wrench to 18
to 20 ft.lbs., turn the screw until the torque is reached. The screw should turn one half to one full turn between
zero lash and torqued. This will give the proper lifter preload. If there is less than one half turn, a longer
pushrod is needed. If there is more than one turn, shimming of the rocker stand or a shorter pushrod is
needed. Scorpion Performance offers shims in .020” thickness, part number SCPRS.020 (32 pieces).

To install the intake rocker arm, rotate engine in normal direction of rotation until the exhaust rocker just starts
to move up (exhaust valve just starts to open). Now install the intake rocker arm using the same procedure as
used on the exhaust rocker arm above. Continue cylinder by cylinder until your installation is complete.
Note: Always use a quality assembly lube such as Scorpion Cam & Lifter Installation Lubricant (part numbers
SRPAL4-1 or SRPAL8-1), on all moving parts.
Important:

 

thank you for your advice and directions to check the pushrod length I used the method where you mark the top of the valve with a marker rotating the engine a few times and see if it's centered. What I got was almost dead in the middle of the valve. Possibly a hair on the back side of the top of the valve indicating I believe it could be short but again just the smallest hair. Do you still believe I need longer rods to correct the problem?

 

I don't know what you need. Those are the directions Scorpion ships with the rocker arms.

 

You need to adjust the rockers so there is .020 - .060 preload on the lifters. It sounds like you have stud mount rockers, not pedestal, so while the above sequence is the same, it's not as cut and dry as torquing the rocker down.

Adjust preload to .040 and you should be fine.

 

Tell us the part number of the rocker arms you have, so that we can give you the proper instructions.

 

Are you sure you have hydraulic lifters?

 

Yes they are hydraulic lifters and yes they are stud mount rockers (scp-1018) thank you for the advice on the preload I'll give that a shot. Do you believe it could also be my push rod length?

 

how would i determine 0.40 preload? I'm not sure what that process would be

 

Yes they are hydraulic lifters.. although the OP seems to believe they are water powered electric generators.

 

Here's a link for installing the rocker arms from Scorpion. These instructions look like they are for stud mount rockers. I suggest giving them a call to verify. Phone 352-512-0800

General valve adjustment instructions
http://scorpionperformance.com/pdf/PI_Valve.pdf

 

You might be able to use the thread pitch to guestimate the part of a turn to use.

 

Thats essentially what Crane has you do with their pedestal mount rockers.

 

The lifter preload is measured between the cup (rod seat) and the retainer/wire lock at the top of the lifter. Adjust the rocker until you get .040 preload by measuring with a feeler gauge between lock and cup, or a dial indicator in a clever position.

The sbf lifter spec is .020 - .060 for the preload, so aim for .04 and accept anything close. You can't follow any "x turn" instructions until you measure a few and note the amount of turn it took, I just measure them all. Either side can vary quite a bit (either head) due to differences in deck/gasket thickness, casting, etc...so it is important to measure and adjust each side independently and not adjust with "x turn" ***** nilly (more important with pedestal rockers and pushrod length but it is worth the note).

 

different length push rods are irrelevant if you lash them correctly...
although motor may not run as smooth
lifters push rods rockers go all new or keep original
mixing new with old is like fixing half the wear