Cam timing in the car? Possible?

[DSPTurtle]

Deep breaths and go back to basics. Dots up at TDC 1 and start over. You shouldnt have to take off LHS cam nut if it's ok but reset RHS to dot up. Make sure you're at TDC 1 though or you'll be like that other guy on the forum that timed his cam backwards. Sounds like you rally understand your gauge and are just using a relative measurement. If it were digital you could zero it. But you way works perfect too. Take your time. You've already done the hard part of pulling the engine back out. If your cam was that far behind the piston is on its was down long before the valves opened. But you can double check with a leak down gauge to be sure you didn't bend anything. Whatever you do, don't give up. You're so close to being done!

[Flat6pac]

You have to do the same thing to the right side. With crank at 360 degrees rotation from #1 set the right side up and rotate 360. At this point you pull the cam pin and move the cam to the 2.4 and pin.
You have to start with both key ways up and both cams pinned. You have 720 degrees of rotation to set up the 2 cams relationship to the crank.
Bruce

[VFR750]

Thanks for the encouragement. It has been a numbing experience.

[Walt Fricke]

I think most of us set our dial indicators to zero when the rocker is on the cam's base circle with 0.1mm lash. Does away with any math at all. After rotating the engine, you watch for the valve opening, and when it gets to the lift specified, see where you are relative to Z1.

I've taken to using electronic dial indicators. Easy to zero, and I can use metric. Not that expensive any more, and you don't have to keep track of rotations of the needle. I've now got two sets for doing this, which is a great help in avoiding right side/left side mistakes as you can watch both while setting either so you can see that one side is on its base circle while the other is opening up toward the overlap spec.

Metric analog indicators for some reason are way more expensive than inch ones (which are cheap), so mainly I have used inches in the past.

[VFR750]

Walt,

My metric dial gage goes from 0 extended to 10 fully compressed. So I have to compress it to some large value, like 9, then rotate the face to get the pointer at exactly 9.00mm. Then target the delta to reach 2.4mm at Z1

Being able to read directly would be nice, but not an option on my dial gage.

I do as you mentioned. Set "9.00" when off the lobe (position at TDC compression) then rotated 360 degrees back to Z1 and read the gage. 6.60mm in this particular case.

I write down all the numbers and steps followed. And I repeat the measurement after final setting.

I mark the sprocket and the drive gear where the pin is. And can easily rotate the two relative to each other to change the timing. I remark the pin location, retorque the bolt, and check timing three times. Keep doing that until I reach the desired value.

That is the fustrating part. I got 2.4 on both sides when I was done. LHS still reads
2.4mm and RHS is barely 0.2mm. It takes another 30+ degrees past Z1 to reach 2.4mm

Today I'll be checking the timing and correcting.

As of last night, leak down showed all cylinders about equal. And all were leaking past the rings (air leak audible through breather port). So that's a bit of good news.

[VFR750]

OK!!!

I am to blame.

I just confirmed that letting the RHS idler drop, when changing out the stomski tool for the real tensioner will exactly cause my problem.

The chain gets pushed back towards the intermediate shaft sprocket. When I lifted the idler to install the hydraulic tensioner, I had to rotate the crank to lift the idler.

Plus I measure the angle of 2.4mm lift currently and it was ~25 off. Now it just took me another 25 crank rotation to lift the idler into position. One tooth.

I now have the smoking gun.

And it is me.

Thanks all for your help.

Oh, and to add insult to injury: "so that's what the red numbers on the dial gage are for!" For going backwards!

Walt, thanks for being patient. I even took pictures confirming my error.

At least I can move forward.

[VFR750]

Funny thing. Pulled pin, rotated crank and stopped 25 BTDC and pinned cam.

Rotated to Z1 and got 2.15mm on first try. Index pin one pin hole over got me 2.45mm. Done.

[Flat6pac]

The last statement is the wrong answer.
You don't pull the pin, rotate the crank, then repin the cam at 25 btdc.
You keep the pin in cam drive until you get to z1 then pull the pin and adjust the cam to your setting then repin. Then rotate 720 degrees and check setting
Bruce

[VFR750]

Actually you can. The cam doesn't rotate with the pin out. So you can reposition the crank relative to the cam, and then pin it.

With the bolted type it is very hard to turn the cam. Is easier to move the crank.

At least it is for me. That's how I did it to prove I was off 25 degrees. Only took one tiny adjustment to nail the required timing.

[Walt Fricke]

I like the old, big nut, style cams when it comes to ease of setting cam timing. You can't rely on the pin settings (at least not without some fancy footwork) to dial it in precisely. You can get a fair range of settings within any one pin setting, locking in the setting you want with the big nut. And really little trial and error - rotate cam to setting you want, and tighten big nut, but not to full torque. Check to see how much locking changed setting. If not enough to bother with, go to final torque on the big nut.

I could approximate this by using a small screw driver against the inner sprocket teeth to move the cam a little. When I tried the bolt with locknut method, the cam always moved some when unlocking the nut, but perhaps with practice I could have overcome that.

I can see how you could just move the crank. Easy if you need to shift the pin (and have figured out which way to go for the change you need). But hit or miss when fine tuning, since you don't have the dial indicator to tell you where you are while moving things.

[VFR750]

I agree with the bolt style and pin there is some variability. I found I could use a small screw driver to rotate the drive gear and it is worth ~0.3mm near the target

Obviously I lost some credibility with my idler gear goof. But overall the Motion of the crank to cam is straightforward. And with some thought I was able to predict what was needed to get close.