Camshaft orientation question

tornik550 · 02-08-2015, 09:35 AM

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?

Flat6pac · 02-08-2015, 10:52 AM

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

tornik550 · 02-08-2015, 12:30 PM

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).

Flat6pac · 02-08-2015, 12:37 PM

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

tornik550 · 02-08-2015, 12:46 PM

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.

Flat6pac · 02:15 PM

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

Walt Fricke · 02-08-2015, 03:10 PM

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.

tornik550 · 03:22 PM

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.

Walt Fricke · 02-10-2015, 09:18 AM

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

Travelin Man · 03-31-2015, 06:44 AM

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/

356RS · 356RS's Garage

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.

Eagledriver · 03-31-2015, 08:26 AM

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

Travelin Man · 03-31-2015, 09:34 AM

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?

356RS · 356RS's Garage

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?

356RS · 356RS's Garage

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?

Travelin Man · 03-31-2015, 12:54 PM

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

Travelin Man · 03-31-2015, 12:56 PM

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

Walt Fricke · 04-02-2015, 02:17 PM

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.

Travelin Man · 04-11-2015, 07:44 AM

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.

Trackrash · Trackrash's Garage

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.