View Full Version : The "Rocking Valves" Adjustment Method


slvrblt2
02-09-2011, 10:06:51 PM
Hey guys, I've already adjusted my valves using the method I'm going to explain, or I'm sure some of you have already heard of it, but I was just curious why it works the way it does? I don't know a ton of stuff about engines and I recently rebuilt my first 350 over the summer with the help of a friend, I guess I just want to leanr more about this kind of thing anyways here's the method I used:

First I wrote the firing order out like this on a piece of paper so I wouldn't confuse myself:confused:

1-8-4-3
6-5-7-2

Then, I pulled the plugs out to make rotating the engine by hand easier, and I rotated it till i saw the #1 valves "rocking", I then adjusted both intake and exhaust for the #6 cylinder.

Next, I watched the #8 valves and I think it was about a 45deg. rotation until you saw those valves "rocking", I then adjusted both valves for the #5 cylinder.

I went all the way through the firing order until I was back at #1, after the #3 cylinder was adjusted (when #2 valves were rocking) one more rotation of 45deg. should bring you back to the #1 cylinder which in all makes 360deg. rotation.

By the way, while adjusting the valves, one hand tightened the rocker nut while my thumb and index finger on the other hand rotated the rod till I noticed it get harder to rotate, I then tightened the nut 1/2 turn.

I'm just wondering why this method works the way it does? For example, what's going on with the #6 cylinder when the #1 valves are rocking? I'd just like to gain more of an understanding of all this, I hope someone can help! Thanks!

-Andrew

rustbucket79
02-09-2011, 10:24:43 PM
When both rockers are moving that piston will be somewhere close to Top Dead Center, and it's "sister" will be close to TDC ready to fire, which is how some people adjust the valves.

Alternatively, rotate the crank so it's at #1 TDC ready to fire (timing mark at "0") adjust those valves, rotate the crank 90 degrees, do # 8, rotate 90 degrees, do #4, etc. IE, go through the firing order.

slvrblt2
02-09-2011, 10:43:38 PM
Alright that makes sense, now about the method you described, you adjust BOTH valves when #1 is at TDC and so on through the firing order? Because I've heard some methods where you only adjust one of the valves then rotate the crank and so on, just seemed a little mor complicated compared to the method you and I mentioned.

rustbucket79
02-10-2011, 01:06:40 AM
Correct. There are several methods, with varying results.

I recall you could adjust 8 different valves with the crank in one position, then a full turn and adjust the other 8. Presumably, only effective with a Stock hyd cam.

EO/IC method: Turn crank until ex rocker starts to move. Adjust intake valve. Continue rotating crank until intake rocker fully opens and almost completely closes. Ajust ex valve. I use this for solid (lash style) valvetrains.

Slowest and most accurate. Rotate crank until rocker is at MAX lift. Rotate crank another complete turn, adjust that valve. This guarantees the lifter is at the cam base circle centerline. Now just do this 15 more times.

And the TDC method I previously mentioned. I use this with 95% of the hyd valvetrains. (that are adjustable)

slvrblt2
02-10-2011, 09:22:50 AM
I remember reading about the EOIC method and then my neighbor explained the method I mentioned above which was much easier, thanks for helping me understand all this!