Camshaft orientation question
 

I just finished the camshaft orientation/ sprocket alignment procedure as specified in Wayne's book. I am pretty sure I did it correctly however I want to make sure.

Both of my camshafts have the dot pointing approximately the same direction. Is this correct?

They are generally the same direction however approximately 5-10 degrees off- does that sound reasonably correct?

You want the key ways up to begin timing. Load the keys, the backing gear, chain, and gear, with tensioners. Pin them both. Now dial gauge #1.
Bruce

So if I did it correctly then my engine (pictured) should be setup generally correct? The arrows point in the direction of the key (dot).

http://forums.pelicanparts.com/uploa...1423430973.jpg

We'll, can you turn it over 720 degrees?
If you can't you have run into a valve and need to reset and retard the pin
Bruce

Yes, I can turn it over 720 without any difficulty. I also checked the valve to piston clearance and I did not have any difficulty. I was a little close on the exhaust valves however I was within spec.

I am almost certain that I did it correctly. So if the keys are both pointing the approximately the same direction and I can turn he engine 720 without difficult- then am I correct in stating that I most likely have them generally oriented correctly?

Sorry to ask this kind of question- I just want to make sure that I have everything correct prior to putting the engine in the car.

You need the cams timed now, not when it's in the car.
And you need some hydraulic tensioners and guards as those are only correct at setup tension
Bruce

Unless you are only using those nice blue things for cam timing, and they will be replaced with hydraulic tensioners of one sort or another.

I have already gone through the sproket alignment and camshaft timing as directed in Wayne's book. I have the large camshaft nuts torqued to 110 ft/lbs. I have checked valve clearance and I am within spec. I have Carrera tensioners on order and will install them tomorrow (if ups pulls through).

i think I was overthinking things. I am almost certain that everything is correct.

You are in good (or at least plentiful) company in overthinking this. Many of us have also underthought it at some point as well.

Doing a rebuild on a 70 911T my question is shouldn't there be a mark on the timing case for the cams to line up on/

No marks on the timing chain housings. You start with the cam key-way @ the 12:00 o'clock position for both cams and with #1 piston @ TDC. Assemble the gears/cam & chain tension. Now your ready to start the cam timing procedure.

There are no marks for the cams. They are almost infinitly adjustable. You start with them vertical and fine tune from there. They are set by measuring the amount the intake valves are open at TDC during the exhaust stroke.

-Andy

Timing Cams
 

So I followed what was said put the cams a 12 O'clock and followed the procedure with the dial indicator. After setting up #1 and #4 continued to install the rest of the rockers and during the rotation on #3 I felt the motor stop it must of hit a valve. No idea where to go from here. Followed the procedure listed here on Pelican and didn't work. What did I do wrong?

If you set #1 timing @ 2.3 - 2.7mm with a 0.1mm valve clearance at the valve overlap TC you should have no problems with #3. You have stock "T" cams right?

In post #3 are the green arrows pointing out the location of the "dot" and key-way? Like at the 6:00 o-clock position? Is this the #1 TC overlap?

Cams
 

Yes stock cams and I put the wide V cam in the left(driver side) and the small V in right.

I just thought about it do I need to take all the rockers out to start all over?

For sure take out the rocker where the valve is hitting the piston. If you still can't get a full 720 degrees rotation, keep taking them out until you can. I assume this won't involve taking out #1 and#4.

Then you can retime things, with valve covers off so you can see and confirm that when the #1 cam is at TDC start of intake stroke, #4 is at TDC firing.

Remember - left cam and right cam dots both up. Pin or lightly tighten both cams. Then measure and set/adjust left cam so you get timing within spec.

Now rotate crank 360 degrees, and time the right cam. At this point, its dot should be roughly down, not up. That puts it at the intake TDC for that side, which is 180 cam degrees, and 360 crank degrees, out of phase with the left cam. The left cam's dot should also be roughly down. Both turn together in that sense.

You can get there without pinning the right side at the same time as you do and start timing the left, but only if you have a good mental picture of how all this works out. Pinning both to start with, so the dots always are at the top and at the bottom together, takes some of the mental side out of it.

I did as you said Walt and started over. I set the left cam @ 2.49mm and then rotated the cam 360 both dots down and followed the same procedure for the right cam and could not get it set. Don't know what I'm doing wrong.

Can't get it set? You mean you can't get the valve lift of the #4 intake in spec at overlap?
Post a picture of your setup.

One thing that I found that was confusing when I have done this, is I have to remember the cams turn the opposite direction of the crank.

http://forums.pelicanparts.com/uploa...1428784352.jpg


You'll see in the pic the dial gauge I rotated the cam to get the 2.49mm the same as the left cam and it went all the way around to the cam lobe again and only read .05???

Confirm that the crank is at TDC firing for #4.

Confirm the punch mark on the right cam is aimed down.

Without looking at the dial indicator, put the pin in the hole that lines up.

Rotate the crank clockwise two turns stopping at TDC. Watch the dial indicator. It should go to zero then back up to close to the cam's spec. If not, then you have some double checking to do.

If it is close to spec when you turn it one more turn then remove the pin and turn the cam till it is in spec and replace the pin.

Report back.

Will do right now and let you know. Thanks for you help

Did what you said rotated it and the dial was a .01?

Forgot to mention. When you rotate the crank make sure that the dial indicatior's tip is always in contact with the valve retainer.

And set the dial to zero when the cam's punch mark is in the down position.

Yeah I did that

I do rotate the cam clockwise to get the valve overlap correct?

Depends. You should be close to the correct number. Turn it so you get the correct value. It shouldn't need to be turned more than a few degrees, if all is well you are just fine tuning it at this point.. Try turning it either way watching the dial.

Replace the pin. Turn the motor over two more times as a double check.

edit: to be clear, to get the valve overlap correct you are turning only the cam, make sure the crank stays at TDC.

I have had the same problem Gordon has had - on one occasion I set the left bank rotating the crank counterclockwise, which meant the cam was going clockwise, and my measurements were for the intake valve being the specified lift away from being closed. Rather than the specified lift as it was being opened. Valves hitting heads, of course, saved me before I got too far into installing all the rockers. Hand slap to forehead, start over. This mistake was easier since my MO is to put the crank at TDC on the pulley, and rotate the cam so I get the readings I want, and then lock it. Easy to forget which way the cam should be going if you are off to start with.

So one approach would be to do the trial setting - both cams dots up, soft lock with the big nut so they are connected (doesn't take much with no springs pushing on rockers etc), and rotate the crank clockwise, watching the cam intake lobes to see how #1 and #4 compliment each other. Then you will have a better idea of where the left intake cam is just starting to come off the base circle. Stock motors don't come off it much, yours with 2.5mm spec will come off it a bit earlier.

While you are sure that the cam is presenting its base circle to the rocker for #1, put that valve in and do a trial setting at the 0.1mm level. Books always call for doing this at TDC firing (when both intake and exhaust valves are closed), but the fact is you can do it any time the rocker is on the base circle, and that is a rather large number of degrees. If you were to set the rocker when the cam is not on the base circle, that would mess up all attempts to time the cam correctly.

Anderson has a good diagram of how to decide which cam is the rabbit ears, and which isn't, and which goes on which side. Dempsey does also. I like to look at that, with the book propped up on the bench, when I put the cams in. I have an engine apart about every other year or so. I remember a lot, but some things one just should not trust his memory on. Right = rabbit?

Also - if somehow the crank pulley, with its Z1 mark, wasn't set right, that would cause troubles. Since it is positively located by a pin, and can only be in one position, that's probably a pretty remote possibility - you'd have to leave the pin out to do it, and who pulls that pin out of the pulley? In a running engine, after, say, a missed shift and a zinged motor, the pin can have sheared and the pulley moved. It will still turn the alternator/fan fine, but it has turned on the crank so it can't be used for timing. But this is after a rebuild?