snakedoctor1

I am trying to tighten my rocker arms up on a 4-bolt main 350. Does anyone know the proper procedure. It seems that I'm getting them as tight as the nut will go, but the rocker is still loose. I don't want to mess anything up or overtighten it. PLEASE HELP!

Stekman

Do a search for setting the valve lash. It's a pretty simple procedure. I guess that's all on the assumption that the rocker stud isn't pulling out or anything.

Token

I totally F'd my valve lash up when I was trying to build my motor last year. Oh what fun that was. Spent three weeks trying to figure out why nothing was working... Then oh me oh my, just because I had my valves too tight


to this day I'm not even sure of the correct way.

brutalform

They will be a bit loose, and they will tick a bit also when you first drive the car. after they pressurize with oil they will quiet down.

1) start with the #1 cyl, turn engine until the intake rocker just starts to lift. This will put the exhaust lifter on the base of the cam lobe.
2) tighten the exhaust until the freeplay is gone in the pushrod. This is "zero lash. Dont collapse lifter.
3)now tighten the nut 1/2 more turn.
4) do all the rest of them the same way.

blacksheep-1

Not if they're prelubed they won't and they shouldn't.

JP86SS

iTrader: (1)

Hydraulic lifters:

When at #1 TDC you can adjust the following valves:

Intake: 1, 2, 5, 7
Exhaust: 1, 3, 4, 8

Rotate the crank one revolution This will let you adjust the remainder of the valves. you should be now at #6 TDC.

When at #6 TDC you can adjust the following valves:

Intake: 3, 4, 6, 8
Exhaust: 2, 5, 6, 7

rotate the pushrods by hand until you feel them resisting to turn easily.
That is zero lash.
Then tighten another 1/2 turn and leave them alone.

That's the way I do them.

brutalform

Yes, I have too. I just didnt want to make things more confusing to someone that is not used to doing them.

vejatabul

i do exactly as you stated, with the exception of me only turning the rocker nuts 1/8th to 1/16 of a turn. it makes more noise, but you get just a tiny bit more lift. i have always adjusted my rockers like this, and even at 6500rpm shifting on a hydrolic flat tappet i had no problems.

JP86SS

iTrader: (1)

I too only do about 1/8 more, but the books say 1/2 so if it's someone new to this its best to go by the book.

blacksheep-1

OK, here goes..........again.
When you install the lifters use a good cam lube like Mellings. I used to use Crane lube but while it's great for the cam, it's hard on everything else. I then place each lifter on a bench, compress it and pump it up with an oil can, you can feel it fill. I then put a dab of white grease on the bottom of the lifter and dip it in Lucas oil treatment. Once the lifters are installed, turn the engine over to (I use #1 tdc, ) any tdc in the firing order. Slowly crank the engine over by hand, as the exhaust valve opens, you adjust the intake rocker. To do this you take the pushrod and move it up and down until there is no slack movement and go 1/2 to 3/4 of a turn more, (I like 1/2), then turn the engine over until the intake just starts to close, that's when you adjust the exhaust rocker by the same method. Run the firing order this way. Then using a drill to prime the engine turn the engine over at least twice to make sure the lifters are oiling to the rockers and you have oil pressure. Put the engine back on #1 tdc compression, drop the dizzy now or later, and start the car. If you have hydraulics you can do it some other (not as accurate)way, but if you have solids this is the only way to do it correctly. I've been doing it this way for over 30 years w/o any problems.

snakedoctor1

Fellas I don't know if I mentioned this but the engine is already in the car. Can I still do the same procedure?

brutalform

Yes you can. You can either use a starter switch to bump the engine, or have a friend do it. Or remove the plugs and turn it over manually...

littlebagz

The amount of valve lash has NO effect on lift. Lift is determined by the camshaft and rocker arm ratio. The pushrod could be as long as a baseball bat and it will only move as far as the lobe on the cam pushes it. The distance travelled by the push rod multiplied by the rocker arm ratio is lift at the valve.

For example if you had a .450 lift cam using 1.5 rockers the differeence in the lobe essentric from closed to max would be .300.

Setting lash takes up the slack in the path of cam , lifter, pushrod, rocker arm, and valve. If this setting is to loose and there is any play, the above parts now slam into each other and begin to hammer each other and cause excessive wear. Hydraulic lifters are designed to have ZERO lash.

Sold cams have to be loose (.015-.030) to allow for the push rod to expand as it reaches operating temperature. Once the push rod is warm and has expanded there is very little lash. (Zero would be the ideal condition) Hydraulic lifters displace oil as the push rod "grows" to maintain zero lash.