What am I missing - Cam Timing

[shrtshck]

Trying to setup the cam timing on a 1987 - 3.2, have reviewed the manual and Wayne's book;
Cams are rotated with the key-way and "930" at the top
Crankshaft is at Z1, confirmed piston 1 is at TDC
Tensioners are snugged on the chain
Alignment pin is in place

Now for the issue, when I rotate the crankshaft clockwise, it rotates less than 180degrees when the dial indicator reads 1.25. The books note that the crank should rotate almost 360 degrees when the dial indicator reaches the set point.

I'm losing half a rotation somewhere, what am I missing, help

[shrtshck]

I was stopping at the initial valve opening with the indicator reading 1.25 mm
Should I rotate through full valve open and stop on the closing with 1.25 of travel remaining?

[john walker's workshop]

#1 intake valve adjusted to .004? shouldn't start moving until at least 300 degrees around. got the cams swapped side for side or was it not apart? do the right side and see if the same thing happens.

[Eagledriver]

Something is wrong. The intake valve on number 1 should be closed until almost 360 degrees of rotation from your initial condition. You are indeed supposed to measure on the way open, not on the way closed. Be very careful not to hit the valves with the pistons. They will bend easily.

When you put the cams in with the Z1 at the top on the pulley and the keyway's up, Number 1 intake valve should be closed and number 4 intake valve should be slightly open. Is there a dot on the cam face? Maybe the keyway is off or the 930 is stamped in the wrong place?

-Andy

[Flat6pac]

You have to pin both cams at the same time with the key way in the up position and then dial in the #1. If you have 1.25 at 180 rotation, you dont have the right pin hole because with stock cams there is no movement of the valve much before 35 or 40 before TDC giving you the setting about 1.25 at TDC.
Bruce

[shrtshck]

I went back and verified that the camshafts are on the proper side.
The clearance is .004

If I ignore the key-way / "930" position on the camshaft and time the dial indicator movement to the crank shaft I can get it timed to have 1.25 mm movement (on opening) at Z1 position. At this position the key-way / 930 mark is approximatly 30 degree off vertical. This is the same for both the left and right bank camshafts.

Are there cases where the key-way doesn't align to the vertical position at Z1 properly timed, for both camshafts?

This is my first rebuild and don't want to have to revisit this once the engine is back in the car.

Thanks in advance for your insights

[Walt Fricke]

1) I assume all is well with your crank pulley? It has a locating dowl pin? And you have figured out which mark amongst the several is the Z1?

2) If so, you can't really go wrong if:

The two cams are rotating such that #1 and #4 intakes are 360 degrees out of phase. At Z1 one valve is opening and the other rocker is loose (and gapped at 0.004". If this is so, you have the cams in basically the right orientation to each other.

Then if the #1 intake is just rising as you turn the crank clockwise and approach Z1, and you adjust it so that exactly at Z1 you are getting the reading (which increases as the crank continues to turn clockwise) which is the spec, than you have that left side.

Same deal with the right side.

At this point it doesn't matter that the marks on the ends of the cams look a bit off of horizontal (or, if you will, vertical, treating the stamping as if a dot). We time our cams with the dial indicator to get the required overlap lift at Z1. The marks on the cams are not there to do that - they are there to get you started, and so that the two cams are in the proper relationship with each other at a gross level before you start measuring.

Pay heed to what Bruce said about starting all this with both cams "up" and pinned. That way you won't lose track of things after you get #1 dialed in, and so won't start off wrong with #2. #2 will still require adjusting, like #1. But you won't be apt to time the right side cam 360 degrees out from where it should be. It is easier to do that than you think, especially if you get interrupted in doing this.

[shrtshck]

The prize goes to John Walker, if it doesn't look right it probably isn't, keep looking till the issue is found.

Had kept the cams and all associated hardware in separate boxes, was careful to only work with only one cam at a time and always return it to the correct box. Must have had a brain fart when installing because the right cam shaft was in the left side.

Switched them and started again, results went exactly as the books say they should.

Lesson learned, when it doubt step back and refer to the Tech Forum, don't rush

Many Thanks for the quick responses.

[Determined]

I too was confused at first.

[viejopatron]

With the help here, you'll make it. However, after I did mine, I paid a PRo to do a check. I had too much time and money invested to let my pride risk it.