Cam timing question

[OldTee]

I am in the process of timing my engine. I installed the cams with the dot to the top on both cams. Then I timed following the instructions in the oh manual. I have them close, but not close enough for me but at TDC the dot on the left side cam is up AND the dot on the Right side cam is DOWN. Can this be correct????

Engine is a 79SC. Cams are Camgrinder ground to dc13. Spec is 1.6mm.

[1982911SCTarga]

You're out 180 degrees on one or the other -- the reference dots should track one another (both up, both down). I got into this when I timed my cams because I pinned the left side and timed it while letting the right cam freewheel. I knew I was out because when I pinned the right cam, it ramped up way before it was supposed to.

With that said, I don't see how it would be possible to be close on cam timing for both cams if one is out 180.

Don't forget "R" for rabbit ears for the right cam and "L" for left (Bruce Anderson's mnemonic).

Brian

[OldTee]

I'm gonna start over tomorrow. It got hot and I decided to stop this afternoon. When I said they were close, I meant both near the same setting (1.6mm) not necessarly togeather.

[OldTee]

I got it now.

Reading Johnny Walkers post on timing did the trick but the following would have been helpful. TDC for #1 and TDC for #4 are one 360 degree turn apart.

1. Set the valve for cyl #1 TDC.
2. Turn the crank 360 degrees and set the valve for cyl #4 TDC.
3. Go back to Cyl 1 TDC. Make sure dots to both cams are up.
4. Set dial indicator for cyl. #1 TDC at "000" left side of engine
5. Turn the crank 360 degrees and set to factory spec (or spec for your cam)
6. Do it again starting from #1 TDC
7. now the right side. Set at #4 TDC.
8. Set the dial indicator on the right side at "000".
9. Turn the crank 360 degrees.
10. Set cam to spec.
11. do it again.

Correct me if I am wrong.

[2.70Racer]

Old Tee,
You got it right. My Camginder Solex cams are one up and one down too.

[OldTee]

Re index the cams. Set the cams so both dots are up at TDC for #1. Then time #1. The timing point for #1 is close to the TDC for #2. Once #1 is close, then rotate 360 degrees to the timing point for #2 and time that one. Both dots will follow each other. Then you can tweak the timing going from one to two. This is the long hand version. Pros take shortcuts.

[mca]

You know, I found something interesting when doing my cam timing a few weeks ago.

With the chain tensioners out you have to mechanically apply tension to the chain. On the left side I used vice grips. Initially I didn't have them tight enough and it threw off the timing procedure. Make sure that side is VERY TIGHT.

The right side uses that mechanical tension tool (you see it everywhere in pictures). It works quite well.

After setting the timing and then installing the chain tensioners you may find that the chain tensioners make the chain much tighter than you could have done mechanically with vice grips or that other tool for the right side.

This will change your timing numbers. Be sure to check your figures again after installing the tensioners. Mine actually advanced a bit but still fell within the acceptable range (964 cam grind - 1.26mm is the normal target). I was very happy that I didn't advance my timing BEFORE installing the tensioners or I would have been WAY off.

Just wanted to throw that out there. Maybe it is common knowledge ... maybe not.

[OldTee]

Wanted to post a bit of a find. Harbor Freight had digital dial indicators for $28.00. A bit of a find. Pics show right side timing and the tools used. The dial indicator needs an extension and the "z" block available from our host. The digital indicator made the adjustments easily understandable and done.

[1982911SCTarga]

I have, and used, that Harbor Freight dial indicator, too. I'm sure the purist's will scoff that we're not within a gnat's butt hair of complete accuracy. Worked for me.

I used one of the six Denso Irridium plugs (you ever price those things?) that came with my cab's engine instead of the fancy-dancy sprocket pin-puller tool.

Brian