Lost on Cam timing

[budzbox]

Ok folks, where am I missing this. I followed the directions in Waynes rebuild book, and got the left side timed. Then I got lost...Correct me where I am going wrong...

After going over 720 degrees (after checking the left side), the cam dots are both on the bottom.

Now, do I check the valve gap and adjust the #4? That is how I read it in the book, so that is what I did.

So, I adjusted like the left side, using the dial indicator. but obviously there is something not right. The left side, now is still pointing down, and the right side (dot) is at like the 8 o clock position. Now, this did not look right, and after trying to check it, it ended up tapping the #6 valve after a short turn of the crank.

So, what did I miss? Do need to turn the crank back to where both cams are facing up? Then start from there for the right side, doing exactly as the left was? I am just so lost here....I have read the directions like 100 times, and checked over 50 messages here, and still am lost. I can't wait until this part is done with!!!

Thanks for any help anyone can offer.

Bud

[2.7RACER]

Bud,
"So, what did I miss? Do need to turn the crank back to where both cams are facing up? Then start from there for the right side, doing exactly as the left was"

Yes, Right side dots up, left side dots down.

Remember #1 fires then 360 degrees crankshaft rotation later #4 fires.

Your problem was going 720. Should have gone 360. Always clockwise.

Have fun,

[sand_man]

"Yes, Right side dots up, left side dots down. "

Now, I'm confused. Shouldn't both dots or keyways or "930" script on the cams always be at the same point? In other words if you start with both cams in the "up" position and the crank at Z1 and turn 360, should both cams now be 180 in the down position? I mean if one side is turning, isn't the other side? I thought the cam pins were supposed to be installed in each side when doing cam timing. At any rate the cams turn at half the crank. So 360 turn of crank yields 180 turn of cam.

[sand_man]

Unless 2.7RACER means that you start the adjustment procedure with left side up (actually both cams are up) and after you've made your turns (360 to check the dial guage then another 720 to return to TDC) right side procedure is started with the cam down...that makes sense - after all of these turns the right side would be down (so would the left).

[sand_man]

By the way you should only have #1 and #4 intake rockers installed.

[budzbox]

Originally posted by 2.7RACER


Yes, Right side dots up, left side dots down.

Remember #1 fires then 360 degrees crankshaft rotation later #4 fires.

Your problem was going 720. Should have gone 360. Always clockwise.

Have fun,

Ok, so I adjust the #1 valve with the dots facing down, then go 360 to adjust the right side, so the dots are both up? I guess I am confused about this because in the book it states that once you set the left, "turn the crank 720 and you are set up already to set/adjust the right side, and the dots should both be down"

Does that sound right? I thought things were going much better this pass than my last one, since I was actually able to go 720 around with nothing binding as before.(long story there)

Also, I left the rockers on, but had them all backed out, thinking that there would not be any problems. Guess I was wrong on that one, at least when you mess up one of the sides...

Thanks

[sand_man]

-Crank pulley at Z1
-Both cams (dot, "930", keyway, whatever) should be up
-Set #1 intake to .004
-Turn the crank slowly 360 stopping at exactly Z1
-both cam markings should now be down
-If the dial indicator reads the correct timing measurment, turn the crank 720 stopping at Z1
-The right side should now be ready: both left and right cam markings will be down
-Adjust #4 intake valve
-Turn 360 and see what the dial indicator reads.

[chancecasey]

It's simpler than it seems.

1. Make sure you set the adjustment screw clearance (.004") when the cam lobe is nowhere near the rocker arm. Go ahead and do this for both #1 and #4 intakes.

2. Put the dowel pin in the left side, turn until you get the correct dial reading (note: put the end of the dial on the valve spring retainer, not the rocker, and make sure the dial indicator travel is parallel with the valve). Could be 1.26mm. Mine is 2.2mm. Whatever is correct for your motor / cam. Stop at the correct dial reading.

3. Remove the dowel pin and rotate crank until Z1 is at the top. Cam sprocket and therefore dial indicator reading should not move/change.

4. Replace dowel pin. Turn crank 720 degrees to double check. Left side is done.

5. Put dowel pin in right side - turn crank until correct dial indicator measurement.

6. Pull out pin and turn crank until Z1 mark is at the top - BUT - 360 degrees after the left side valve was starting to open. You can see this visually just by looking the cam lobe on the left side and making sure it isn't about to open the #1 intake. If it is, rotate the crank another 360 degrees. Replace pin in right side, rotate crank 720 degrees to double check. Now you are done.

7. When you're done, #1 and #4 intakes should open exactly opposite, that is, 360 degrees of crank rotation apart. If they open at the same time, you need to change one of them by 360 degrees of crank rotation. Note that each valve opens every 720 degrees of crank rotation - and they are 360 degrees apart. So when you are turning the crank, at Z1, one side will open, then the next time at Z1, the other side will open.

8. Double check everything with the dial indicator.

9. Use 2 devices to tension both sides of the chain at the same time. Don't clamp down too much.

[sand_man]

Originally posted by chancecasey
It's simpler than it seems.

1. Make sure you set the adjustment screw clearance (.004") when the cam lobe is nowhere near the rocker arm. Go ahead and do this for both #1 and #4 intakes.

2. Put the dowel pin in the left side, turn until you get the correct dial reading (note: put the end of the dial on the valve spring retainer, not the rocker, and make sure the dial indicator travel is parallel with the valve). Could be 1.26mm. Mine is 2.2mm. Whatever is correct for your motor / cam. Stop at the correct dial reading.

3. Remove the dowel pin and rotate crank until Z1 is at the top. Cam sprocket and therefore dial indicator reading should not move/change.

4. Replace dowel pin. Turn crank 720 degrees to double check. Left side is done.

5. Put dowel pin in right side - turn crank until correct dial indicator measurement.

6. Pull out pin and turn crank until Z1 mark is at the top - BUT - 360 degrees after the left side valve was starting to open. You can see this visually just by looking the cam lobe on the left side and making sure it isn't about to open the #1 intake. If it is, rotate the crank another 360 degrees. Replace pin in right side, rotate crank 720 degrees to double check. Now you are done.

7. When you're done, #1 and #4 intakes should open exactly opposite, that is, 360 degrees of crank rotation apart. If they open at the same time, you need to change one of them by 360 degrees of crank rotation. Note that each valve opens every 720 degrees of crank rotation - and they are 360 degrees apart. So when you are turning the crank, at Z1, one side will open, then the next time at Z1, the other side will open.

8. Double check everything with the dial indicator.

9. Use 2 devices to tension both sides of the chain at the same time. Don't clamp down too much.

Okay, so then you're saying that the dowel pin is NOT installed on the right side while you're doing the timing on the left?

[chancecasey]

Yep, no dowels to begin with, and all this dot stuff is just needlessly confusing.

1. Make sure neither #1 or #4 intake rocker is near the lobe, and the screw is properly adjusted at .004" clearance.

2. Left dowel in, turn crank until proper valve lift (e.g. 1.26)

3. Left dowel out, turn crank to Z1. Left dowel in again. Done with left.

4. Right dowel in, turn crank until proper valve lift.

5. Right dowl out, turn crank until Z1 (making sure the #1 is not beginning to open - if it is - turn another 360). Right dowel in. Done with right.

I've left out the double-check steps, but you get the idea.

[sand_man]

Originally posted by chancecasey
Yep, no dowels to begin with, and all this dot stuff is just needlessly confusing.

1. Make sure neither #1 or #4 intake rocker is near the lobe, and the screw is properly adjusted at .004" clearance.

2. Left dowel in, turn crank until proper valve lift (e.g. 1.26)

3. Left dowel out, turn crank to Z1. Left dowel in again. Done with left.

4. Right dowel in, turn crank until proper valve lift.

5. Right dowl out, turn crank until Z1 (making sure the #1 is not beginning to open - if it is - turn another 360). Right dowel in. Done with right.

I've left out the double-check steps, but you get the idea.

Won't this put your cams 180 out? If the dowel is not installed on the right side and you started with both cams in the "up" position and you turn 360 and then another 720, the left cam will be down and the right will still be up. I've read other posts where people have indicated that both cam marking are usually in the same place.

[chancecasey]

So you had all the rockers on, albeit backed off, and felt binding? You know, you CAN bend valves just turning the crank by hand.

[chancecasey]

Originally posted by sand_man
Won't this put your cams 180 out? If the dowel is not installed on the right side and you started with both cams in the "up" position and you turn 360 and then another 720, the left cam will be down and the right will still be up. I've read other posts where people have indicated that both cam marking are usually in the same place.

See parenthetical portion of step 5. If #1 is about to open then rotate another 360. My method assumed you didn't pay attention to any dots. So confusing. One of my cams had 2 dots !

If #1 and #4 open at the same time, then remove the dowel from either side and rotate the crank exactly 360 degrees and replace the dowel.

Of course double check everything with the dial.

If you're really good you can just eyeball the dots and forget all about the dial indicator

[2.7RACER]

Chancecasey,
Your description is absolutely correct.
I'm afraid folks need to remember three key things.
1. This is a four cycle engine. Takes 720 degrees crank rotation for everything to happen.
2. The camshaft makes one rotation for two crank rotations.
3. Number one fires then 360 crankshaft degrees later number four fires.

When all is right, the numbers, dots, keyways, you choose, will be up when number one fires, and will be down when number four fires.

When setting number one dots, keyway, numbers down.
When setting number four dots, keyway, numbers up.

If you do this, you will not get one and four compressing at the same time. Simple.

When you are done, leave the motor in number one TDC compression.
That is dots up.
Then when you install the distributor the rotor must point to number one. Usually around 3 o-clock position.

[chancecasey]

Yep - absolutely.

[Alan L]

Here is another way to approach it. All the Z1 stuff is correct, but takes a bit of brain strain, unless you are doing it regularly.
What I have done on my current strip down is to mark where the dowel pins go in , on both the inner and outer cam wheels.
I used white out fluid. I also marked the cam wheels - LS and RSides.
With a bit of luck, this should get me back to the same spot I was at before stripping it down. With the dial gauge, I can then tweek the timing if needed - by a degree or whatever. But the basic timing will be correct from the start.
Have yet to assemble this way - but should work.
Alan

[bbh03]

I don't understand why it matters if the dial indicator (and hence the cam) moves when tightening the left side to the torque spec. Once the pin is in, everything should remain the same, right? Even if you allow rotation, the cam is now fixed relative to the crank (assuming chain not slackened at all). Am I missing something?

[Mike Juzenas]

Originally posted by bbh03
I don't understand why it matters if the dial indicator (and hence the cam) moves when tightening the left side to the torque spec. Once the pin is in, everything should remain the same, right? Even if you allow rotation, the cam is now fixed relative to the crank (assuming chain not slackened at all). Am I missing something?

I found that the pin was not enough...you can get movement with the pin in around the spot you want it timed to. From a rough to medium precision you are correct but if you need to tweak it bang on or your cam happens to be very steep right there just a little bit of rotation can mean a signficant amount. I found on my 993 that the valve lift at TDC was at quite steep and just a little adjustment mean I was out. Even the slop in the pin was enough so it took several iterations to get both sides the same (which is key for a smooth engine).

If the dial moves that means the cam moved which means that you are 1) moving the cam relative to the chain/crank or 2) loading the chain to the crank. I found that I could hold the cam quite still and get the proper torque value in...tricky but after a few iterations it become easier.

Oh, and I did the classic mistake of having my right hand cam 180 degrees out. I must of been having a brain fart when timing the cams on the stand. I then reset the right hand cam while the engine was in the car which was both not fun nor pretty but doable...a 12 hours mistake!

Cheers,

Mike

[shbop]

Damn, I couldn't figure-out why the book said to torque the cam nut each time. Now I understand. With the slop in the fit, between the pin, gear etc., it's enough to throw things off. Thanks Mike! I've been reading and reading, getting ready to do mine, and I couldn't figure-out why it would be neccessary to torque the nut fully on each try.

[2.7RACER]

Mike,
That is what I was talking about re: the "dots"

Whether it's dots, numbers, or the keyway, they need to be the same at TDC.

Both up for number one compression or both down for number four compression.

One up and one down doesn't work. As you know.

Sorry about the 12 hours.