Cam Timing and What's the Setup for Bi-directional Adjustment?

[viejopatron]

I'm timing the engine shown in the photo. I've consulted books and threads for some example of my dilemma, but haven't found it. Please read on.

With the crank in position, the camshaft needs to be independently rotated to a valve displacement value. Right.

OK, so if I remove the pin, the cam and crank can now turn independently. But, the large retaining washer under the bolt head needs to be removed or, at least, the bolt backed out.

But if that's done (loosen bolt), the cam can't be rotated in either direction. I installed a spacer under the bolt head (no contact with retainer) and torqued. I've found no mention anywhere of the use of a spacer.

Hmmmm... what have I done and what is the accepted way to do it? Or am I being anal about wanting to rotate in both directions.

[2.7RACER]

Gary,
I don't see any problem with your use of a spacer under the bolt to hold and rotate the cam.
That or a longer bolt that will bottom in the cam. Whatever it takes to hold and turn the cam.
Easier than other methods.

[MBEngineering]

HI check out this thread," setting cam timing with bolt-snout "cams it may help you set the cam timing.

regards mike

[viejopatron]

Thanks Kids

That's encouraging.

Mike - be a good chap and provide a hyperlink. I tried multiple searchs, but no joy. Cheers.

[MBEngineering]

HI Gary just bumped the cam timing thread up for you to look at as I do not know how to hyper link it,"setting cam timing with bolt-snout cams", hope it is of some use.

regards mike

[Bill Verburg]

Here's a link to the cam timing thread MBE is referencing
bolt-snout cam timing

[viejopatron]

I took MBE's input and edited it to help me. No guarentees that I got it correct.

Basically, his method reduces tendency of shaft to self-turn by adding exhaust rocker arms and removes the pressure off the pin by reversing direction of crank. Very cool. Thank you.

1. Put the engine on Top-Dead-Center (TDC) and the cams with the dots to the top. Fit the timing gear and pins.

2. Fit the inlet rocker arm on Cylinder 1 and set the clearance.

3. Fit the exhaust rocker arm and set the clearance.

4. Put the Z holder block on and the Digital(?) Total Indicator (DTI) and set to zero.

5. Turn the engine over to TDC and check the TDC reading.

6. If the cam reading has not changed, turn the engine to take the reading past slightly (0.2mm) TDC and STOP. Remove the bolt.

[If you take the reading slightly past, remove the cam bolt and try to remove the timing pin, it will be under pressure. To compensate for this, back the crank (approx 0.2 mm as indicated on DTI). This releases the pressure on the pin.]

7. Remove pin.

8. Turn to TDC and refit the pin and bolt.

[When you go to TDC, re-fit the pin and then turn the crank, you will see slight movement between the sprocket and the cam gear (approx. 0.2mm) which you have already allowed for when you went past your setting]

9. Turn over to TDC on Cylinder 1 and check the DTI is at "0". Continue to turn crank and check timing again. If OK, torque the bolt and check again.

10. Fit the Cylinder 4 inlet rocker arm and set the clearance.

11. Fit the exhaust rocker arm and set the clearance.

12. Swap the Z holder to Cylinder 4 and repeat Steps 5 through 9.


Notes

1. Since you have both rocker arms fitted, the cam should not rotate when the pin is removed.

2. When you do a full turn to check the timing you have already allowed for the movement in the pin and the cam timing should come up to your setting.

3. If the cam setting is not in the pin hole you had and the adjacent holes are too far offset, then release chain tension and remove the cam gear. Rotate the gear 90 degrees (approx) and re-fit to camshaft. This should put the pin location in a better placement for adjustment.

4. If the timing is still not playing ball, i.e. cannot install pin, then you may need to change the chain gear for a different one.