e3photo

Well, the new year is off to a good start, as I just finished timing the cams. Thanks to Steve Weiner for input and guidance, Wayne's book, and Anthony (Axl911 on Rennlist)

I used Anthony's write up because he condensed it into easy to follow steps. I installed a mechanical lifter on #1 and gapped it to .1mm. I then installed a Z block from Pellican, and installed a digital dial gauge and pre loaded it, then zeroed it. I did not have enough shaft to preload a full 10mm, but figured it was the initial few mm's that were important. When the digital dial is zeroed, it will show the deflection of the intake valve as a negative, which makes sense. I then proceeded to follow these steps...

To set timing for Cylinder 1.
1. Rotate the pulley so Z1 mark is lined up with the case parting line.
2. Install cylinder 1 intake rocker.
3. Make sure both cams have the dots pointed straight UP. Draw a line from the dot through the center of the cam will make it easier to see the dot is pointed straight up.
4. Put the pin into the cam sprocket where the holes line up. Do this for both sides. You can put the cam sprocket bolt in or not. Leaving it out makes it easier to see how the dot moves.
5. Adjust the cylinder #1 intake valve clearance to .1mm like you normally do in valve adjustment.
6. Mount your dial gauge on cylinder #1 intake. And set it to zero value.
7. Rotate the crank pulley clockwise almost 360 degrees. As you approach the Z1 again you will notice the dial begin to move.
8. Continue to rotate clockwise until the gauge moved 1.26mm or .05 inch. STOP.
9. Is the Z1 mark lined up with the case parting line? If not, use a small screw to remove the pin on the left side cam. Rotate the crank pulley until the Z1 mark is lined up with the case parting line.
10. Now put the pin back into the cam sprocket where the holes line up.
11. Double check by rotating the crank pulley 720 degrees. By the time the Z1 comes around for the second time, when the Z1 is lined up with the crank pulley, your dial gauge should have moved 1.26mm or .05 inch.
12. You are done with cylinder #1. Don’t move anything.
13. If it takes more than 360 degrees to get the dial gauge to move 1.26mm, then you either don’t have the cam dot pointed straight up at the beginning or you did not adjust your cylinder 1 valve clearance properly.

Now to set timing for Cylinder 4.
1. After completing the last step in setting timing for cylinder 1, the dot on the right cam should be pointed straight DOWN.
2. Install cylinder 4 intake rocker.
3. Adjust the cylinder 4 intake valve clearance to .1mm like you normally do in valve adjustment.
4. Mount your dial gauge on cylinder 4 intake. And set it to zero value.
5. Rotate the crank pulley clockwise almost 360 degrees. As you approach the Z1 again you will notice the dial begin to move.
6. Continue to rotate clockwise until the gauge moved 1.26mm or .05 inch. STOP.
7. Is the Z1 mark lined up with the case parting line? If not, use a small screw to remove the pin on the RIGHT side cam. Rotate the crank pulley until the Z1 mark is lined up with the case parting line.
8. Put the pin back into the cam sprocket where the holes line up.
9. Double check by rotating the crank pulley 720 degrees. By the time the Z1 comes around for the second time, when the Z1 is lined up with the crank pulley, your dial gauge should have moved 1.26mm or .05 inch.
10. You are done!!!
11. If it takes more than 360 degrees to get the dial gauge to move 1.26mm, then you either don’t have the cam dot pointed straight up at the beginning or you did not adjust your cylinder 4 valve properly.

I used a Stomski top dead center tool to verify my Z1. I also found that when I determined which way the pin needed to be moved, I had to turn the crank so the valve closes, otherwise when the pin is removed, the valve spring will cause the cam to rotate.
I also used two Z blocks and two dial gauges so I could verify both sides.

I can now start at Z1, turn the crank 360, and the gauge on #1 reads 1.25, and the one on #4 is 0. I turn it another 360, and the gauge on #4 reads 1.23, and #1 is 0. I can repeat this continualy and read the value from 1 then 4.

Here are a couple of photos, and am I missing anything? I had heard that the cam timing was one of the trickiest steps, so now that I have done it, I am a bit paranoid that I missed something.

Thanks again,
Emerald

IXLR8

What method did you use?

Many use a dial indicator on the top of the piston and look for the reading to peak as they rotate the crankshaft. The problem is, at the top, the crank can be turned both ways quite a bit (degrees-wise) for no movement of the dial indicator.

The method I use using a dial indicator, I find a location BTDC that gives me a certain reading on the dial indicator...I mark the pulley...I then go past TDC to the same reading and mark the pulley again. The location between the two marks is your TDC.

BTW, when taking readings with the dial indicator, you should approach the reading from the same direction...say...increasing.

e3photo

Hi Alex,

I believeI used a method similar to yours, only with the Stomski tool. I determined where the piston appeared to be at it's top limit. I marked this spot, and checked either side of it. I felt pretty good about Z1. You also make a good point about always measuring in the same direction. I have a great respect for those that can do something like this, and then remember all the details when they write it up. I am so glad to have a job completed, that my write-ups aren't always as specific as they could be.

Emerald

race911

Did you recheck after the bolts were torqued? Not as big of a deal, from my experience, on these low overlap cams as the old S (or racing) profiles of yesteryear. I seem to remember when I put the yellow car's engine back together last year, and backdated to the pins, there was a couple thou of play in there that I had to adjust out. Again, not that big of a deal.

e3photo

Hey Ken,

Yeah, I rechecked after the bolts were torqued. I went in for a snack, came out and put the chain tensioners on and timing chain cover, and I spun it around and checked again, before removing the dial indicator setup. I think I got it right, but it took a while.

Thanks for the input.

Emerald

Mike J

Everyone has a few variants on how to do this, but sounds good. I took an old mechanical lifter and had to grind it to fit, did you have to do this?

You must have a 95 or early 96, the later cars do not have the indexed sprockets, nor the woodruff keyway on the cams. Mine did not have the indexed sprockets, so I “updated” those, but my cams had the woodruff keyway. If not, I would have had the keyway machined.

I also fiddled with the chain tension a bit to make sure I did not get much variance, i.e. I confirmed that the chains were tight enough so that “more tight” made no difference.

Did you check to see what the factory settings were before you reset the cams? Mine were quite low, closer to 0.6mm.

Where you got 1.26mm as the desired lift? As far as I know, the number is not published by Porsche, Gerry Woods recommended 1.0mm for the 993 stock cams, which is what I timed mine to. Are you cams stock?

I also found the Z arm on my 96 993 did not align properly so I could be 90 degrees to the top of the valve in order to get a good measurement. I see it seemed to work for you, great. Its been a few years since I did this, not sure why I could not get it to work. I ended up building my own jig to hold the dial indicator.

I find a sparkplug removes the pin fine, the thread is the same on the top (for sparkplugs with removable tops), and its cool to see the plugs rotate around.

I had verified the TDC before when I had the heads off so I did not have to verify it again.

I found that you have to be careful sometimes to make sure that the cam does not get dragged when you rotated the crankshaft back to TDC at the correct setting. It happened once.

I also did not like doing this without the cam bolt at least being in hand tight, just paranoid.

I found the .1mm clearance very critical since the ramps on the cam are quite steep, and its easy to get variances at TDC due to that measurement. Its not an absolute since it requires a bit of a feel to know how tight the rocker should be clamped on the feeler gauge to assure a 1.0mm setting. Did you double check that setting after some rotations?

You did not miss the critical issue, which is the 180 degree rotation between the right and left hand sides of the engine. I actually missed this first time around, and had to retime the cams with the engine in the car, that was a whole lot of fun.

Here is my feeble attempt while on the engine stand:

http://www.pcarworkshop.com/index.ph...timing_Part_II

And in the car later after I realized I screwed up:

http://www.pcarworkshop.com/index.php/Cranking_it_up

Cheers,

Mike

e3photo

Hey Mike,

I actually studied your build as well before I started, forgot to mention it.
I to have a 95, but the engine I'm building, came out of a 97, but oddly enough had the indexed sprockets and mechanical lifters. I think it had been modified before I got it. I made chain tensioners, but got lucky with the Z block. I was glad it worked as I do not have your skill for fabrication. I also preferred having cam nut on, as I wanted everything firm. I will have to check, but I found the timing numbers in another build write up. Hopefully I haven't messed that up.
It feels good to have the short block assembled.

Emerald

e3photo

Mike,

I went back and checked to see about the lift of 1.26. I found it in a previous post by another RL'r and then I checked the table in the back of Wayne's book and he gives a value for the 3.6 engine as being a range from 1.16 - 1.36 with 1.26 being the desired amount. I may have to double check with Steve.

Emerald

axl911

Isn't the 1.26 for the 964 engine?

On the 993 engine there is no spec issued, but on several recommendations I remembered setting mine at around 1.15.

e3photo

The 1.26 is for the 964 engine. I thought it would be similar, as they are both 3.6.
I used your write up and assumed you were using 1.26 for a 993 engine, but maybe you did a 964 as well. I may not be done yet.

Emerald

axl911

I used 1.26 for my 964. But for my 993, I definitely used a different value. I recalled it was 1.15.

e3photo

Thanks, I'll have to check on the value then. No need to go further till I am sure.

Emerald

rsr91128

Sorry no answers just more questions, but a very good thread indeed.

This is a spec page from the 993 tech manual.

Problem is what exactly is the definition of these circled words?

I read it as if it is checked manually it should be 1mm lift with zero valve clearance (I guess using the hyd lifter? under pressure? or does that not matter if you are just manually turning the engine? does the little spring in the lifter keep up if you are just turning the engine over by hand?)

Of course they only show adjustment with the factory "set it and forget" tools so who knows. I guess if you had a fancy digital degree wheel like Colin you could verify that 1 degree of rotation from BTDC to TDC = 1mm of lift on a 993 intake cam but I have not seen that verified. Has anyone checked it?

I plan to check mine but I am curious what the answers are and which tools I actually need to buy or make.

e3photo

Hey Eric,

yeah, sometimes it is clear as mud. I know that for the later series 993 engines, Porsche changed the sprockets and had special tools for setting the timing. It looked like a simpler way to set the timing, but when I priced the fancy tools, they were over $600, and you have to buy aftermarket as OEM tools are NA.

I contacted Steve Weiner, as he has always been so helpful and knowledgeable. He said my 1.26 was fine and that I was good to go. There are probably many opinions on settings, but I trust Steve, so I am moving on with the assembly.
I hope to install my new rockers and shiny new Hargett valve covers tonight.

Thanks,
Emerald

e3photo

Well things checked out, and it was time to button things up. I installed new rockers and lifters, put on the timing chain covers and tensioners, then installed my new valve covers. I remember reading that the tops are much harder, but I thought the tops were just as easy, maybe easier due to fewer bolts.

Emerald