Lifter Preload Procedure?

SCrazy

SCCoA Member
What exactly is the procedure for setting lifter preload.

I thought that with a valve fully closed (piston at TDC compression) you torque the rocker arm nut to 18 ft/lb but not more than 1 turn or less than 1/4 turn from first contact.

A couple of other questions:

Do the lifters need to be "pumped up" in some way before doing anything? How do you do this?

Can you simply torque them once or will torque change as fluid is forced out of the lifter?

I'm gonna go after them tonight and I hope for some quick help.
 
Pitch thread of stock rocker arm bolts is 1.25mm=.049", so 1/4 turn is only .012, not enough. I'd go for a half turn or slightly more. You should torque them in a couple steps waiting a minute in between, to allow the lifter to bleed down. I went for 22 lb-ft, 18 may be not quite enough.
 
OK Cool but how do I get oil in the damn things to begin with. My motor is brand new with only some assembly lube in the thing.

I plan on spinning the oil pump to get things flowing with a spare shaft I have but is this enough?

Do I have to turn the engine over a few times?

Thanks
 
OK I've got the procedure figured out now but my pushrod seems to be way to long at 7.400". I go about 4-1/8 turns from zero lash to 20 ft/lbs.

Looks like new pushrods for me. Any idea if there is a way to equate number of turns on the adjuster nut to pushrod length so that I don't have to measure them.

Thanks
 
I usually like them 1/2 turn past zero lash. That will give you about what you are looking for. I think you need somewhere around .035 to .050 in preload. Keep in mind your cylinder is going to grow when it gets hot so I like setting them to 1/2 turn past zero lash which will give you about .025 in preload. This is slightly tight but like I said as soon as the engine heats up the heads will gorw and they will loosen up a little more. I used 7.250 inch push rods on my custom grind which set all of my intakes up perfectly and the exhaust vlalves needed a .010 shim under each rocker pedestal. I used the motorsport roller rockers which aren't adjustable.
 
i mostly tighten rockers until i can barely turn the pushrod then turn the motor about a turn and check them all again ,,

and turning the oil pump with a long shaft and a drill works good for building oil pressure before starting i mostly just crank it over a few times to build oil pressure
 
I like to set up a dial indicator on the lifter plunger and tighten the rocker bolts until I get .045 of travel. The recomended preload on the lifters is(if I remember correctly) .040-.050.
Why would you want them looser? Are you using adjustable or pedestal mount rockers?
You can soak the lifters in a bowl or something that is filled with oil. Take a pushrod and work the plunger up and down a few times, that will fill them with oil.
Why do you have 7.400 pushrods?
 
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Well a loose vlave ( not too loose mind you) is a happy vlave. I would rather be on the edge of the loose side than the tight side. strange things happen when valves get too tight.
 
90sc35thann said:
Well a loose vlave ( not too loose mind you) is a happy vlave. I would rather be on the edge of the loose side than the tight side. strange things happen when valves get too tight.
Yes but 0.025 is way too loose! youre giving up some lift at that setting and thats a pretty good ways away from the edge of loose.
 
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a 7.400 rod is WAY too lng, I have 7.200 rods and they are too long with a high lift cam, we had to shim them to get them to work. Why do you have 7.400 pushrods?
 
Well I'm feeling a little stupid here but I found out what was going on and why I was having so much damn trouble getting to a proper torque spec on the retaining nuts.

MY ROCKER ARMS ARE NO LONGER PEDESTAL MOUNT LIKE STOCK BUT HAVE BEEN CONVERTED TO STUD MOUNT.

So to set preload you simply adjust to zero lash plus 1/2 turn and lock in the adjuster nut. You can never get to a torque spec since the arms float on the stud and do not ever bottom out.

Also I have confirmed the 7.400" rods are the right length even though they seem incredably long and were specifically picked for the new valvetrain geometery. What a circle jerk for a simple answer.

Thanks for all the replys.
 
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Ohhh....I see now.
Well I still set those like I described earlier. I havent set a lifter like that(1/2 turn method) since my cough..cough..chevy..cough....cough days.
Glad you got it figured out.
 
I have the Crane regrind in my engine with .509 lift. Crane 99838 springs and Comp Cams 7.2 pushrods and Motorsport Roller rockers. I have new Crane lifters and ticking lifters... fairly noisy. I pulled it down once and thought I had bad lifters several had .130 play before the slack is picked up. Put 3 new ones and I thought should be okay and it still is noisy.

Could I have too short of pushrods. I think I may need longer pushrods or grind the pedestals down to get the right preload. Seems you would only use shims when the lifter is being compressed too far?

How do you use the dial indicator to measure the preload? The one I saw for sale had a magnetic base. Do you use something like that or do you just use the indicator freehand?

While I have it down I will be replacing my header gaskets with the 95-mustang metal ones to make sure that a exhaust leak is not at issue either.

Any input would be appreciated.
 
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