How to check timing on a /6 with engine in car. Options

[tornik550]

How do I check timing with a timing light on a /6. I know how to set the static timing however I want to check with a light. I have seen that some cut an acess panel in the firewall. I don't want to do that at this point. There isn't enough room to fit a timing light.

[Mike Bellis]

Pull the motor and tranny and start and time it out of the car.

Use mirrors to see the mark and flash the light.

Cut an access hole.

[laflaur]

Check the timing at the flywheel. There should be a cutout on the transmission,and there are timing marks that can be used. loosen the distributor,and rotate to advance/retard timing.

[fixer34]

AFAIK, and how I've done it, there is an access hole on the top of the case above the flywheel. There are TDC and full advance marks on said flywheel. The hole is large enough to get a finger in there to scrape/sand away rust and put paint on the marks.

The daunting part is that you set the running timing for full advance at 6000 rpm, leaning over the carb stacks. One hand on a timing light, and one to adjust/turn the distributor. Helps to have someone in the cockpit holding the throttle at 6000 also.

[larryM]

AFAIK, and how I've done it, there is an access hole on the top of the case above the flywheel. There are TDC and full advance marks on said flywheel. The hole is large enough to get a finger in there to scrape/sand away rust and put paint on the marks.

The daunting part is that you set the running timing for full advance at 6000 rpm, leaning over the carb stacks. One hand on a timing light, and one to adjust/turn the distributor. Helps to have someone in the cockpit holding the throttle at 6000 also.

X2

- that's all correct so long as you still have an oem 914/6 flywheel

aftermarket and replacement 911 flywheels have the timing marks in the "wrong" place for the 914/6 viewing slot

if you have a good "advance type ' timing light you set it to ZERO and dial up the advance reading when it turns 6000

you can also do this with a mirror watching the pulley marks (which you have brightly marked) by using a dial-advance type tool

even better - cut a porthole in the firewall like our GT's have, and just do it thru the front - see picture







.

[rgalla9146]

First step is to pray you have a stock flywheel.
Second step is to loosen the dizzy clamp just enough that you can move it, but tight enough that it stays where you put it until you can tighten it with the engine off.
Third step is to wear a glove on your dizzy hand to avoid upsetting your pacemaker.
Wear a tight shirt.

[mskala]

First step is to pray you have a stock flywheel. ...

Not exactly, you need to have the proper flywheel for the _engine_ you put
in there. IIRC his is not a 914-6 engine. Not sure what markings are on the
flywheel, but even if they are present, it is a good idea to get one of those
appliance-white-paint-touchup bottles with the brush and mark them very
visibly. You will need TDC and whatever is spec for your engine; could be
35 degrees BTDC or 30 degrees BTDC for earlier motors, or 5 BTDC or 5 ATDC
for different later ones.

If there are no marks on the flywheel and the engine is already in the car, I
think it would be impossible to _accurately_ transfer from the pulley to the
flywheel without pulling the engine first.

[tornik550]

My engine is a 2.7l with JE 9.5:1 compression pistons and E cams.

I have a flywheel that does not have timing marks. The engine is already installed in the car.

Shouldn't I simply be able to find TDC for Cylinder 1- put a paint mark on the flywheel at TDC. Find the appropriate timing numbers for my engine. Use a timing light that has adjustable advance- set the timing light to the appropriate advance- rev up to 6000 rpm, twist the distributor until the TDC mark lines up. That way it shouldn't really matter if I have any timing marks other than TDC.

Am I correct or am I missing something?

[rgalla9146]

First step is to pray you have a stock flywheel. ...

Not exactly, you need to have the proper flywheel for the _engine_ you put
in there. IIRC his is not a 914-6 engine. Not sure what markings are on the
flywheel, but even if they are present, it is a good idea to get one of those
appliance-white-paint-touchup bottles with the brush and mark them very
visibly. You will need TDC and whatever is spec for your engine; could be
35 degrees BTDC or 30 degrees BTDC for earlier motors, or 5 BTDC or 5 ATDC
for different later ones.

If there are no marks on the flywheel and the engine is already in the car, I
think it would be impossible to _accurately_ transfer from the pulley to the
flywheel without pulling the engine first.

Not exactly...... leave the engine in the car.
You can make or buy a tool to find TDC.
Then use a timing light with advance feature to set the right timing for your application.
The tool you need is an adjustable piston stop that extends through the spark plug hole. It can be made by tapping the center of an empty spark plug and threading a long bolt through so that it can be extended or retracted as needed.
You rotate the engine in one direction until the piston touches the stop. Near TDC.
Then in the other direction until the piston again touches the stop.
Real TDC is the mid-point between those two stops. Exactly
No flywheel but an original 6 (or 906) is marked for timing.
Sorry for assuming you had a stock 6, many have replacement flywheels from 911s.
This method is also useful on any engine to verify true TDC on the pulley.

[larryM]

CORRECT - just do it

even better - first static time it using the pulley notches

TDC is notched on the front pulley

(along with the other 2, so be sure you get #1 TDC by method as above)

also usually is an advance notch close next to the TDC notch -

all you need to know is here - 911 pulley marks

Shouldn't I simply be able to find TDC for Cylinder 1- put a paint mark on the flywheel at TDC. Find the appropriate timing numbers for my engine. Use a timing light that has adjustable advance- set the timing light to the appropriate advance- rev up to 6000 rpm, twist the distributor until the TDC mark lines up. That way it shouldn't really matter if I have any timing marks other than TDC.

Am I correct or am I missing something?

[r_towle]

Interesting,

I wonder if someone could simply glue a piece of polished stainless steel to the back of the firewall and leave it there, then air the light in the area and use the mirror to see the marks up front....

For setting timing at 6000 rpms, which is crazy, I would just tie off the throttle body with a zip tie at the correct rpm and go from there. I drove On my way! once like that when I broke the accelerator cable.

[messix]

timing at 6k rpm? (IMG:style_emoticons/default/screwy.gif)

how much more advance comes in after 3-4k rpm? (IMG:style_emoticons/default/shades.gif)

seems a little extreme.... (IMG:style_emoticons/default/stirthepot.gif)

[messix]

and it should be one of the more important things to remind people to do when doing a 6 conversion is to find absolute tdc and mark the flywheel as such and mark the desired advance mark before the engine is installed.

[patssle]

and it should be one of the more important things to remind people to do when doing a 6 conversion is to find absolute tdc and mark the flywheel as such and mark the desired advance mark before the engine is installed.

NOBODY MENTIONED THIS ANYWHERE AND I DIDN'T DO IT! (IMG:style_emoticons/default/hissyfit.gif)

[mskala]

timing at 6k rpm? (IMG:style_emoticons/default/screwy.gif)

how much more advance comes in after 3-4k rpm? (IMG:style_emoticons/default/shades.gif)

seems a little extreme.... (IMG:style_emoticons/default/stirthepot.gif)

Dude, have you seen the distributor curves for the early motors?

[mskala]

...
Shouldn't I simply be able to find TDC for Cylinder 1- put a paint mark on the flywheel at TDC. Find the appropriate timing numbers for my engine. Use a timing light that has adjustable advance- ...

Am I correct or am I missing something?

Yes, this is correct. Beware that if there are issues with getting all the
pulses and nothing but the pulses to the gun's sensor, then its advance
setting won't work well. I have had problems with both of my guns getting
crosstalk or something. YMMV

[messix]

nope.

please post up one.

i have a very hard time believing that a porsche six is that bad of a design that it takes until 6k rpm to get all the advance in.

that suggests that the combustion chamber design is very inefficient and has trouble controlling flame front.

[fixer34]

timing at 6k rpm? (IMG:style_emoticons/default/screwy.gif)

how much more advance comes in after 3-4k rpm? (IMG:style_emoticons/default/shades.gif)

seems a little extreme.... (IMG:style_emoticons/default/stirthepot.gif)

Dude, have you seen the distributor curves for the early motors?

Just goes to show that when you ask a question, it should be qualified if ANYTHING is other than stock. When the question asked 'how do I time a /6', I answered with what is appropriate (and documented) for a factory car with a /6 engine.
Yea, I wasn't real keen on leaning over that engine while it was screaming at 6000 rpm, but I figured the Porsche engineers who wrote the owners manual knew more than I did. They gave me a way to set it.
Now if you change something like the flywheel or engine, well, some of the above answers will probably help.

[messix]

timing at 6k rpm? (IMG:style_emoticons/default/screwy.gif)

how much more advance comes in after 3-4k rpm? (IMG:style_emoticons/default/shades.gif)

seems a little extreme.... (IMG:style_emoticons/default/stirthepot.gif)

Dude, have you seen the distributor curves for the early motors?

Just goes to show that when you ask a question, it should be qualified if ANYTHING is other than stock. When the question asked 'how do I time a /6', I answered with what is appropriate (and documented) for a factory car with a /6 engine.
Yea, I wasn't real keen on leaning over that engine while it was screaming at 6000 rpm, but I figured the Porsche engineers who wrote the owners manual knew more than I did. They gave me a way to set it.
Now if you change something like the flywheel or engine, well, some of the above answers will probably help.

i bet it was the engineers sense of humor that wrote that....

lets see how these driving glove pansy's like working on the car when it's making all this noise at 6,000 rpm and is pissing off all their neighbors with all the racket.....

(IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/av-943.gif)

like in the 914 manual .... 1st step for everything in the manual... remove engine and transmission.

[mskala]

nope.

please post up one.

i have a very hard time believing that a porsche six is that bad of a design that it takes until 6k rpm to get all the advance in.

that suggests that the combustion chamber design is very inefficient and has trouble controlling flame front.

Not at home so these are not the best graphs, but:
This is a Marelli from some version of 2.0T:


This is a bunch of other types shown together: