im studying over the preload stuff now. is there anyway you can dummify it down for me? im still confused on this concept.
Ok, you seriously need to stop making assumptions. Even if you have stock lifters, pushrods, and rocker arms, that in no way guarantees that you have proper valvetrain geometry OR proper lifter preload. I think it's safe to assume since you seem to not know how to check your valvetrain geometry or what preload is, that you have not checked these things. This is not an insult, but it is a reminder that these things are critical to a quiet, durable, correctly working valvetrain (it's a whole system, remember!) and you need to check these things.
Just assuming because things are "stock length" that they work just won't do. Jay Allen of Camshaft Innovations has a popular saying (paraphrase): "If you are using stock-length pushrods, then I guarantee you are using the wrong-length pushrod!"
That statement is almost always true because there are SO MANY factors that could require you to change your pushrod length or require a change in your valvetrain geometry. These factors include, but aren't limited to:
head deck squareness
head gasket thickness
cylinder heads used (also any milling done)
Cam lobe profile
lifters used
rocker arms used
valve stem height
so on and so on.........
The reason why you need to ALWAYS check valvetrain geometry and pushrod height when changing things like your cam, etc. is because ANY change in those variables (and others) can lead to a REAL CHANGE in required pushrod height, etc.
Hypothetical Example: If you have a stock engine, and swap out your heads, cam, lifters, rockers, etc. Let's say for the sake of argument that these changes dictate (when measured) a .050" shorter pushrod than stock. If you bolt your new combo all together with the stock pushrods, having not checked valvetrain geometry and lifter preload, than you could be close to bottoming out the plunger in the hydraulic lifter bottom (if it was severe enough). You wouldn't even realize it, but you would be shortening the life of your valvetrain and have noise issues.
How to check Valvetrain Geometry Procedure:
1. Have all of the components installed that you will be using on your "new" setup (eg. heads, head gaskets, cam, lifters, etc etc).
2. Take a marker, such as a sharpie, and "color in" the valve stem tip on one of your valves.
3. Go ahead and install a pushrod (it's ok to start with stock length here, since this is just a measurement and not necessarily the final setup) and rocker arm on that valve. MAKE SURE to follow the rocker arm adjusting and/or installation procedure for that type of rocker arm before you continue.
4. Turn the motor over by hand through a couple revolutions (to allow the rocker arm to push down on the valve stem tip at least a few times).
5. Now REMOVE the rocker arm. The tip of the rocker arm will have worn away some of the marker you had filled in on the valve stem tip, and created a "witness mark". The thickness and location of this witness mark will TELL YOU if your pushrods are creating a proper valvetrain geometry, or if the one you used is wrong and you need a different length.
6. Ideally, you want the witness mark to be a thin line, mostly centered on the valve stem tip. If the witness mark is too far out on the "exhaust side" of the valve stem tip or too far out on the "intake side" of the valve stem tip, then you know you need different length pushrods. Now would be a good time to purchase a pushrod length checker tool!!!
Example of witness mark thin and centered:
How to check for proper hydraulic lifter preload:
Hydraulic lifters have a "plunger". When people refer to achieving "zero lash" before making the final tightening on an adjustable rocker setup, what they mean is that all of the vertical slop between the lifter plunger and the rocker arm pushrod seat have been taken up, but that the pushrod has not pushed the plunger down yet. Checking lifter preload is verifying that the lifter plunger is not out of range. With the rocker arm torqued down (pedestal) or adjusted approx. 1/2 turn (adjustable stud), that lifter plunger should be between .020 and .060" below the snap-ring aka. lock ring in the lifter.
One way to check this, and Rick91GT has another great way (you can practically invent any way to check this), is to lay a piece of metal or any flat surface across the valve cover mating surface of your cylinder head. When you have achieved "zero lash", use the flat metal as a place to scribe a line on the pushrod. After you have torqued down the rocker (pedestal) or made your approx. 1/2 turn (adjustable stud), that will have pushed the pushrod down into the lifter a little bit. Now, make a second scribe line on the pushrod using your flat metal as kind of like a straight edge. Then, measuring the distance between the two scribe lines on the pushrod will tell you how much lifter preload you have.
Helpful Reading:
http://www.carcraft.com/techarticles/116_0401_setting_pushrod_length/index1.html
http://www.cranecams.com/?show=faq&id=6
without it being jacked up. I put in a ARP chromoly shaft and new pump....Moral of the story, Account for all your metal rings in your gaskets or get a gasket without any of them....
