Check your cam timing after setting initially! Don't be like me

[Tippy]

EDIT: Since my post is not making sense to many, this was where my right cam (bank 4-6) was sitting with Z1, one crank stroke, and then turning another 360 to Z1 again when I checked timing after running engine for quite awhile. I decided to advance the cams as I set them severely retarded (forgetting to use new overlap settings) during refresh and going to 993SS cams from C3.2.. How it ran as good as it did is remarkable….

How's this for being too advanced or retarded? I had the crank on Z1 both turns and look at where the dots were on the right bank.

I set the timing and accepted all is well. Big mistake.

Nowhere in the Bentley nor the book I used for reference does it tell you where to look at for a baseline to check each bank independently.

Surprisingly, the engine ran ok and all the way up to WOT under boost. I wanted to advance the cams and found this egregious mistake.

This is a 3.4L 7.5:1 CR motor running 993SS cams from Doherty, so thankfully I'm running flattop pistons or there would have been some love between the pistons and the exhaust valves if they were high-CR ones I'd imagine.

Photos for a good laugh......

[porschedude996]

Let me get this straight. Your Crankshaft is at “Z1”, and the Cam Dots are at 2 and 8? Shouldn’t the be at 12:00?

[mikedsilva]

yeah, I'm not following either...

[Tippy]

Originally Posted by porschedude996

Let me get this straight. Your Crankshaft is at “Z1”, and the Cam Dots are at 2 and 8? Shouldn’t the be at 12:00?

Yep

[JoeMag]

Ok... So is this a quiz? I see several things that suggest both pics are the right bank (4-6)

1. The timing gear on both pics has the dish side facing the motor
2. If first photo is 1-3, it's upside down. Tensioner is on top
3. The dripping oil and the sealant pattern is the same in both pics.

[boyt911sc]

I tried several times to read and understand the message of the OP. I’m still not sure what the message was all about(?). Still bewildered about the post.

Tony

[GG Allin]

I believe both pictures are of the 4-6 side taken 360 degrees of crank turn away from each other. It looks like the cam is advanced 40-50 degrees.

Or maybe I'm just dead wrong...

[Tippy]

Originally Posted by GG Allin

I believe both pictures are of the 4-6 side taken 360 degrees of crank turn away from each other. It looks like the cam is advanced 40-50 degrees.

Or maybe I'm just dead wrong...

Yes.

I don’t know how to word any different. Maybe I should give my bachelors back, it’s not working LOL

[panama911]

Cam is the same (right bank) in both pics, first at Z1 for #4 and second at Z1 for #1?
Cam is retarded, not advanced, by about 20 Cam Deg/40 Crank Degrees?
That is a LOT of retard - but if you had posted only the first pic, that would have saved us from a lot of confusion :-)

[pocv0]

I don't understand. Those dots on the camshafts are for installing the cams to get them in the ball park. Timing of the cams requires a dial indicator and a degree wheel (?) What am I missing ?

[gled49]

Tippy, it’s time for Professional help the straighten this out.

[mikedsilva]

[TibetanT]

In the second picture of the right-side cam, I can see he is using a dial-indicator for timing.

I am no expert on this subject, but I will say that the video above (posted by mikedsilva) helped me understand the basic and using the dial-indicator.

What is difficult is knowing exactly where the timing marks are on the "bolt-type" cams.

What I ended up doing was putting a mark on the outside of the cam wheel in order to keep track of where the alignment was/is while turning the crank with the washer and bolt in place. The video is helpful but those are the earlier cams and it is easier to see where the dots are, but a PITA to torque.

Appreciate the video!

[Tippy]

Originally Posted by panama911

Cam is the same (right bank) in both pics, first at Z1 for #4 and second at Z1 for #1?
Cam is retarded, not advanced, by about 20 Cam Deg/40 Crank Degrees?
That is a LOT of retard - but if you had posted only the first pic, that would have saved us from a lot of confusion :-)

Yeah, I didn’t take the time to figure if it was super retarded or super advanced from ideal.

It was just OFF and that’s all that matters. It is bang on now.

[Tippy]

Originally Posted by pocv0

I don't understand. Those dots on the camshafts are for installing the cams to get them in the ball park. Timing of the cams requires a dial indicator and a degree wheel (?) What am I missing ?

You don’t time with a degree wheel like American stuff, you adjust by overlap of the intake valve by using a dial indicator on the retainer.

[nospiners]

Originally Posted by Tippy

You don’t time with a degree wheel like American stuff, you adjust by overlap of the intake valve by using a dial indicator on the retainer.

Αbsolutely correct . And it makes it a lot easier to have dial indicators on both banks
For quicker more precise setting.. It can get very confusing if you have only done American engines and do not grasp the difference

[JoeMag]

...regarding truly timing the cam with degree wheel versus over-lap. I'd propose it depends on what level of performance or accuracy you're looking for. Doing over-lap you're timing to a single point and really do not know if the cam is really made to "specification" (lift and lobe separation).

In various stages of my race engine development I've purchased two cams in the last ~3-4 yrs. Both were not to spec, at least in my mind using a degree wheel to time them. Earlier one was supposed to be 106 lobe angle. Left was fine, and right was pretty far off at 111. Most recent is being rechecked by someone else.

[stownsen914]

I'll echo JoeMag's experience in having a pair of matched cams with different lobe centers. I timed them using the factory method (#1 and 4 intake lift at TDC), and then being curious, checked the exhaust lift specs, and then checked everything with a degree wheel. After initially being confused why I was getting different results left to right, I realized one cam's lobe separation was off by several degrees. I either advanced or retarded one side by a couple degrees (I forget which) to "split the difference" so to speak when I set the timing.

[phunt]

Everything I see even read on cam timing says set the valve lash. My cam card shows lash .004 but says valve timing is at zero lash.
Also the cam is times at some sort of overlap. Like 1.1 to 1.4 mm with 1.25 as ideal. My card shows non of that.
Lashing the valves does change the cams timing. But when everything gets hot at operating temp that lash is supposed to close to zero.
When using a degree wheel you put the measuring device, dial indicator, directly on the lifter or cam lode. So zero lash so to speak. That is the only true way of knowing the cam’s timing.
Now according to my cam card and specs given. Setting timing by lode center line is the only choice I have. There isn’t an overlap figure listed. If I was to just go by that overlap number based on engine type, like my 3.2, how could that possibly be accurate?

[boyt911sc]

Originally Posted by phunt

Everything I see even read on cam timing says set the valve lash. My cam card shows lash .004 but says valve timing is at zero lash.
Also the cam is times at some sort of overlap. Like 1.1 to 1.4 mm with 1.25 as ideal. My card shows non of that.
Lashing the valves does change the cams timing. But when everything gets hot at operating temp that lash is supposed to close to zero.
When using a degree wheel you put the measuring device, dial indicator, directly on the lifter or cam lode. So zero lash so to speak. That is the only true way of knowing the cam’s timing.
Now according to my cam card and specs given. Setting timing by lode center line is the only choice I have. There isn’t an overlap figure listed. If I was to just go by that overlap number based on engine type, like my 3.2, how could that possibly be accurate?

Phunt,

At the bottom of the spec card, it says the valve timing is measured at 0.05” (1.27 mm) of valve lift (360° from Z1 for cylinder #1). At this point, you are ready to do cylinder #4 (another 360° rotation back to Z1 for cylinder #4) using a degree wheel or the crankcase mating line. Your over lap should be 1.27 mm (+/- 0.13). The measurement data using a degree wheel is more convenient and reproducible compared to the visual method. Both procedures work well.

Tony