Re: 360 Engine Assembly ?\'s
Let me go through it again...
The lifter has a piston inside it.
That piston moves up and down on a spring actuating a set of valves.
That 'Piston' is referred to as the 'Plunger' in a lifter.
That lifter is full of oil.
The cam starts to push the lifter up against the push rod, and the push rod pushes down on the plunger (or piston, what ever you care to call it).
When the plunger is depressed by the valve spring pressure, it forces oil out of the lifter, up through the push rod to the rockers.
At some point, the piston bottoms out inside the lifter, and the lifter then starts to move the rocker arm and valve stem against the valve spring pressure.
The idea is to pre-load your valve train a little, keeps things from vibrating and adding extra wear.
By judging how much you have depressed the piston in the lifter, you can tell how much pre-load you have on the piston in the lifter.
Most guys just spin the push rod between their fingers, but from the time the piston leaves the seat (a snap ring in the top of the lifter), until it bottoms out on an internal seat, you can't tell how much pre load you have.
Too much pre load, and you won't get adequate oiling to the top end,
The spring pressure will feel the same (and you add lube to both ends of the push rods, and your fingers), but you have lost piston 'stroke' to pump oil, too far down and the piston will cover the incoming oil inlet, and it's a good way to have an already 'tight' top end go into coil bind and wipe out your camshaft...
Not enough pre load, and you will have push rods and rocker arms vibrating loose, and hammering on things every time the cam lobe comes around.
You will also loose lift at the valve (the cam lobe has to take up the slack before anything moves) and that will cost you power.
Not to mention the hideous noise that loose valve train components make!
If you have machined the head, Machined the top of the block, used aftermarket head gaskets, or used new rocker mountings, you need to check the 'Stack Up' height of the engine and your lifter requirements.
1. I make sure the lifter I'm working on is on the base circle of the cam, if you are on the ramps or lobe, things aren't going to work out...
2. I assemble the top end, rockers, push rods, lifters in the bores, just don't tighten them down yet...
3. Then I use a dial indicator on the piston in the lifter.
4. I tighten the valve train down until the piston is depressed more than 0.030" but not more than 0.060".
(0.030" is the most common recommendation of the top three lifter manufacturers in the country for stock applications)
5. If you have fixed rockers, ones that bolt to the head directly, like some of the AMC V-8's did, you may have
more depression than 0.060". In that case, you will have to shim the rockers up.
Use proper shim stock so you don't get off a some crazy angle.
Shim the rocker mount up until you are under the 0.060" max.
6. If you find you can't make the piston go down 0.030", you may have to pull the rocker mount, and CAREFULLY file off a little of the mount where it meets the head.
The EASIEST (not the best, but acceptable) way is to buy a sheet of window glass, lay the glass on a flat surface, tape a piece of very fine sand paper to it, and sand away at the bottom of the rocker mount, BEING CAREFUL TO KEEP THE MOUNT FLAT ON THE SANDING BLOCK.
(this same trick works to flatten warped water neck gasket surfaces, oil pump plates, ect...)
Clean the part THOROUGHLY before returning to your engine assembly.
(glass as thick as you can afford. Keep an eye out for a store with a broken plate glass window, and have a piece cut from the scraps, Very cheap, and very good for checking flat...)
As for keeping the dial indicator inline with the piston with the push rod in place...
They make a little arm that allows you to inspect at right angles.
You can also just tighten down until you take all of the slack out of the push rod (all up and down movement is restricted) then mount a normal straight run indicator at the top of the rocker arm over the push rod pocket, and tighten the rocker arm down and torque it.
If the total downward movement of the push rod pocket, (and hence push rod and piston) is between 0.030" and 0.060", you win!
If it's more than 0.060", you will have to remove the rocker arm mount and shim it.
If it's less than 0.030" downward movement, you will have to remove the rocker mount and remove a little material where it meets the head.
Any downward movement will be easy to inspect like that.
(that's the only way to do it on some of the tiny lifters put into European engines)
That's the good part about the 'Floating' rockers that Chevy uses, instant adjustment since the rocker mount never bolts solid to the head, you can just tighten the nut until you get 0.030" and forget it...
I know this is a hard concept to grasp when so many people have been teaching you to 'Bolt it down and forget it' for so long, but there is Horsepower & Torque to be found here...
And it's FREE!!
Brhino, for you I'll find a picture. I'm getting ready to go through a 360 in my garage, and I'll have to do just what I've described, and I can take some pictures then...
So many cats, so few recipes...