Cam timing question, partially assembled engine guru needed

[Krieger914]

I had to disassemble my 3.0 to fix a broken piston ring on #1 from a recent rebuild. I decided to completely disassembled the heads/ housing on the 1,2,3 side. The 4,5,6 side I did not. I pulled the cam housing, heads, cam and rockers as one unit. In building things back up I put the 4,5,6 side back on as one unit with the cam and all the rockers. I have backed out all the valve adjustments except for intake #4. The 1,2,3 side I have installed heads, cam housing, cam and intake rocker #1. No other rockers are on this side. So finally the question. Will I be able to accurately set my cam timing like this? I'm not being lazy, I just don't want to break, loose or damage something removing the remaining rockers from 4,5,6, but I will. Or should I add all the rockers for 1,2,3?

[targa72e]

You can do it with out all the rockers. I usually only install first intake rocker on each side to time cams.

john

[gled49]

U can do it like u say, but after all the rockers are in on the 1-2-3 side, double check the cam timing on both sides.

[Walt Fricke]

I think backing the rockers off on the unaffected side is more than you needed to do. The reason most of us, doing a full top end, just do #1, and then #4 (and could do it the other way around, but we don't), is that it is a bit easier to set things up having less rather than more spring pressure to deal with when moving the cam. On the other hand, having other springs at work kind of counter balances the pressure of the valve you are working with, so it probably is a wash. Another reason to do just the first two is if you run into issues you have less wasted work if you decide to disassemble and recheck.

It is reasonable to expect that nothing changed on the unaffected side - how could it? However, you could check #4 (after resetting the lash) as a way of understanding where it is, so you can match #1 to it.

[Flat6pac]

I’m trying to imagine exactly what you were doing.
You can leave everything together as a unit.
Back the crank down about 30 degrees so all pistons are down in the cylinder
Install the head unit complete, both sides.
Turn the cams key way up then bring the crank to Z1 install the gears on chains and pin
Set your timing.
Bruce

[Steam Driver]

I’m it a guru by any means but here’s my experience. When (trying to) time my cams using the one-rocker technique, per Wayne’s book, I was plagued by cam “snap back.” After making the initial setting when I removed the pin to rotate the crank back to Z1 the cam would immediately and instantly rotate off the setting. This is because of the valve spring tension (operating through the rocker) acts on the cam lobe, rotating the cam.

Someone on this forum, Bruce I think, suggested installing all of the other rockers with the adjusters backed off. Voila problem solved. All those other springs and rockers applied enough pressure on other lobes to counter-balance the forces and the cam stayed in place. Cured my frustration!

[Krieger914]

I am sorry I wasn't clear in my description of what I did. I rebuilt the engine about three years ago. I didn't put a lot of miles on it. Some time after I realized I had broke a piston ring on #1. Recently I disassembled the motor to a short block to make the repairs. On the right side of the motor I pulled the cam housing and heads as one chunk and I did not disassemble the valve train. On the left side of the engine I disassembled the heads from the housing including the valve train.

It almost seems more realistic to have both cam and all the rockers assembled and lash adjusted? Jeez, maybe I should just pull those right side rockers and follow Wayne's book...

Thank you guys for the input!

[Walt Fricke]

I think we were all imagining you had left the left bank completely alone, other than backing off the rockers.

All you did which was a bit out of the ordinary was to pull heads on one side as a unit, and disassemble the other side for some reason. So both sides need retiming.

I'm sure you can get it done without pulling those other rockers. Just have at it. Several ways to skin that cat.