aaddpp

I set about checking the timing on my car - model year 1987 - with a dial indicator set up as well as the 32vr. I set up the devices on cylinder bank 5-8 and followed the procedure for each individually. I used each method twice to be sure it was repeatable...and the results for each test were similar.

As is shown in the photos below, I having an issue making the dial indicator and 32vr agree with each other. The 32vr is showing near spot on timing with maybe 1 degree advance timing. On the other hand, at 2|0 the dial indicator is showing 1.425mm deflection on a cylinder bank that should be 2.0mm +/- 0.1mm. I have posted photos of each step in the process so you can see what I saw.

Note: I have a Porkensioner installed

Any thoughts on what might be going on here?


Dial Indicator Method

Procedure Used - Rotated engine to TDC. Installed dial indicator on intake valve of cylinder #6 (photo in WSM shows this to be the valve further forward on #6) and set gauge to zero with 5mm pretension. Made best effort to align dial gauge with cylinder.

Initial Position Balancer
http://www.flickr.com/photos/51967142@N00/5299837155/
Initial Position Gauge
http://www.flickr.com/photos/51967142@N00/5299837091/
Gauge Allignment
http://www.flickr.com/photos/51967142@N00/5300433132/

Read Position (based on 2|0)
http://www.flickr.com/photos/51967142@N00/5300433062/

Gauge showing deflection at 2|0 - shows 1.425 deflection...should be 2.0 +/- 0.1mm
http://www.flickr.com/photos/51967142@N00/5299836907/

Balancer position with dial indicator at approximate 2.0mm deflection (went a touch past zero)
http://www.flickr.com/photos/51967142@N00/5299836825/

Dial indicator at about 2.0mm deflection
http://www.flickr.com/photos/51967142@N00/5299836761/

32vr Method

Procedure - Rotated engine to TDC and installed 32vr. Manual calls for even tightening of bolts so I used a torque wrench and 25 inch-lbs which was about right for the 1/8 to 1/4 turn of the bolt specified. Installed the reader and took reading which was about 1 degree advanced.

Blancer Position - TDC
http://www.flickr.com/photos/51967142@N00/5300432754/

32vr Reading
http://www.flickr.com/photos/51967142@N00/5300432680/

Mrmerlin

you should try this match with the used belt,
as it will be prestretched.
It may give different readings

Lizard928

This is showing a larger discrepancy than thought because advanced would have a higher lift sooner rather than later.....

Oh Ken where are you....

Cosmo Kramer

Did you have the 32VR on same side as the dial indicator at the same time? Are you 100% sure everything was locked down?

aaddpp

Each test was done independent of the other...I pulled the 32vr each time I decided to use the dial indicator. As for locking down, I hand snugged down the bolt securing the VW 387 by hand and tightened the three 32vr bolts with a torque wrench to 25 INCH-LBS which seemed to give me the 1/8 to 1/4 turn specified in the instructions.

Kens tool is so straight forward so I can't find any error there, so there must be something on the dial side - just guessing.

jcorenman

One thought-- the dial-indicator is on the intake cam, while the 32v'r measures the exhaust cam-- and your chain tensioner is not pumped up, because there is no oil pressure. So the chain will either be slack on the top or bottom, depending on which intake valves are doing what. That will make a few degrees difference, no??

PorKen

A new belt will have about 1-2° advance until it is 'seasoned'.

Is the engine at T|0, #1 cylinder? This is where the 32V'r is most accurate.

Differing valve openings at #6 T|0, and at both 4|5 settings stretch the belt differently, changing the reading up to 2°.

borland

aaddpp,

OK, they are not in agreement. Using 32vr, what is the difference in degrees for cyl #6? Eyeball from photo, looks like 5 crank degrees (2.5 cam degrees) difference.

Once you calibrate the 32vr against the WSM and your new belt, then later with seasoned belt, you can recheck or reset cam timing using only the 32vr tool.

worf928

Have your cams been out recently? If so - and maybe even if not - check that your intake and exhaust cams are indexed correctly. See WSM 15-127. It is very difficult to eyeball the marks with the engine in the car. 1/2 chain link off looks correct when it is, in fact, not. When the index marks on the two cams are aligned there should be exactly six chain links between the two marks. WSM shows 5 full links and two half links on either side.

123

From another thread:

jcorenman

With all due respect to the original poster, this makes no sense:
I don't know much about grinding cams, but I would think that the index of the keyway relative to the cam lobes is fundamental to the cam-grinding art.

As for the rest, the key is a snug fit in both cam and hub, and the hub itself was certainly made with a CNC machine, even in the 80's. It's possible that the hub was machined on one machine and then the holes drilled and threaded on a different machine, with potential errors, but that doesn't seem likely-- unless it was Fritz with a drill-press. And even if it was a different operation, they would have to index off of some feature, and the keyway is about all there is. So I am not buying it.

I think the answer, in this case, lies with the intake vs. exhaust cam.

aaddpp, if you are not doing anything this evening, could you repeat the check with the exhaust cam?

Imo000

Any chance the Porkensioner plays a role in this?

blown 87

All I know is that when I do a set of gears on a four valve, the intake of one valve on number one and number six are where the factory wants it to be.

123

If all of that was machined so accurately, why would Porsche make the cam sprockets adjustable, and have the whole dial indicator cam timing setting procedure, complete with factory produced training video on how to do it? If all of those parts were so precisely machined, I'd expect the procedure to be "slip cam sprocket onto cam, and tighten bolt".

blown 87