axl911

Hi all,

Everyone knows the later 993s have the fiction type cam sprocket to camshaft which can slip and causes power loss. So, it would be a good idea to have a procedure to check to see if and how much slippage occurred.

I am thinking of doing this while I have the engine out for a clutch job. It shouldn't be too hard, but I need you to double check my procedure below to make sure it sounds right.

This procedure is only to check the timing, and does not change anything in the engine.

Equipment Required:
- Metric or Inch dial gauge with extension tip
- Z block or suitable holder for holding the gauge to the engine
- Older style 964/911 solid lifter rocker arm (ground down to fit) with the elephant's foot screw and retaining nut
- Valve adjustment feeler gauge with 0.1mm (or .004 inch) blade

Procedure:
- Drop engine and remove upper valve covers and both timing chain housing covers
- Remove sparkplugs to make it easier to turn the engine
- Remove cylinder 1 intake valve rocker
- Install the older style 964/911 solid lifter rocker arm
- Rotate the crank to cylinder 1 TDC
- Using the feeler gauge, adjust the valve clearance to 0.1mm with a slight drag
- Mount the dial gauge onto the engine to read the top of the valve spring retaining collar, and zero the reading.
- Rotate crank 360 degrees and note the amount of movement of the gauge. This is your intake valve stroke in overlapping TDC with .1mm valve clearance value.
- Do the same for cylinder 4.

Now the values of cylinder 1 and 4 should be around 1.0 to 1.2 from what I've read. Cyl 1 and Cyl 4 value should also be the same. Anything smaller would indicate timing being retarded, larger being advanced. Also, if the values are not similar bet 1 and 4 then timing is not balanced between the cylinder banks.

Is the above procedure correct and make sense? Anything missing?

thanks,
anthony

chris walrod

This will be fine for a spot check, and therefore you really dont need to remove the chain covers. That said, to do it -properly- you'll need to remove the tesnsioners and set chain tension with the P-tool and, of course, the tool number escapes me now.

Many have improvised in setting the chain tension with other means. Trick is to set both sides the same as this will distort your readings.

Some 1995 models have the trusty pinned iteration chain wheels. What year is your car?

AOW162435

Chris,
With a 7/94 build date, would my engine have the 964-style cam wheels?

Andreas

axl911

Chris,

You are absolutely right!!! Tottally forgot about putting tension on the chains. Guess I'll have to add a power steering puller or a modified disc brake pad spreader.

You're also right that I don't need to remove the timing chain housing cover, but I just want to check to see what type I of cam/sprocket type I have on my 95.

---
anthony

chris walrod

To be honest, I have never been able to find out exactly when 'updates' were installed during production. Same for the slide-on second gear that some early 993's have. Nobody who I have asked knows as I guess its was never that important for Porsche to make this information availble.

7/94 build, I would bet money it has the early style chain wheels.

AOW162435

Thank you Chris.

Andreas

JasonAndreas

Engine serial numbers greater than the following were probably updated (I'm not 100% positive on the engine numbers so someone should confirm/double check);

M 63S 05848
M 63S 52685 - TIP
M 64S 04238
M 64S 51181 - TIP
M 63S 85654 - RS
M 61T 00932 - TURBO

The transmission serial number breakdowns for the 2nd gear changeover, 3rd & 4th gear guide sleeve and needle cage updates are;

G50.20 - 02693
G50.20 - 02174 (M220)
G50.21 - 05072
G50.21 - 03094 (M220)

chris walrod

Jason -- great information! Thank you sir!!!