Help in setting ignition timing

[Joost van der Velden]

I have some question about static timing. I have connect a 6V lamp between my distibutor and the ground.

Please see attached image. I presume the TDC is the mark in the middle of OT??? When should the light go on? Is it 3 degrees towards the O or 3 degrees towards the T? In my opinion above the T because the light should go on before passing TDC but I would like to make sure.

On the other picture you seen the distributor. This picture is taken while the TDC mark on the pulley is in line with the crankcase marking. What could cause that the rotor does not point directly to the marking?

Thanks,
Joost
BTW; I have a S90 therefor it is 3 degrees and not 5

[Michael Eker]

The firing point is 3 degrees before top dead center (BTDC); this is equivalent to approximately 3.6 mm to the left of TDC ("OT").

You need to check also that the distributor shaft is meshed in the correct position in the

toothed drive:

Position piston in Cylinder 1 on firing point TDC.

The coupling slot in the pinion shaft is off center.

When installed, the pinion shaft must be so positioned that the slot is directly

perpendicular to the longitudinal engine axis with the smaller section of the pinion shaft top

facing towards the crankshaft pulley.

If you need to move it:

Remove fuel pump, insulating flange, gaskets, and actuating plunger .

Lift distributor pinion shaft by pushing up and turning to the left through orifice of fuel pump

receiving flange. You can turn the shaft one tooth at a time until it is in the correct position.

Caution - do not drop the thrust washer into crankcase interior !!!!

meker

[Glenn Ring]

Before Top Dead Center is clockwise toward the "T".

The distributor looks like its advanced quite a bit more than 3º.

Personally I never use static timing. I always use a modern timing light and time it at full advance. I also like a light where you can "dial in" the advance. This means the TDC mark is illuminated when you reach the "dialed" advance. You don't need a degreed pulley or to mark your stock pulley. You just need the TDC mark.

I have a OTC that I purchased a number of years ago that does 6v or 12v, tach display and adjustable "advance". It was not cheap but well worth the investment.

[Glenn Ring]

The firing point is 3 degrees before top dead center (BTDC); this is equivalent to approximately 3.6 mm to the left of TDC ("OT").

You need to check also that the distributor shaft is meshed in the correct position in the

toothed drive:

Position piston in Cylinder 1 on firing point TDC.

The coupling slot in the pinion shaft is off center.

When installed, the pinion shaft must be so positioned that the slot is directly

perpendicular to the longitudinal engine axis with the smaller section of the pinion shaft top

facing towards the crankshaft pulley.

If you need to move it:

Remove fuel pump, insulating flange, gaskets, and actuating plunger .

Lift distributor pinion shaft by pushing up and turning to the left through orifice of fuel pump

receiving flange. You can turn the shaft one tooth at a time until it is in the correct position.

Caution - do not drop the thrust washer into crankcase interior !!!!

meker

While it's "nice" to have the distributor drive in correctly it is not mandatory.

(VW Type 1 picture) but you get the idea.


All that matters is when #1 is at TDC you can rotate the distributor so that the rotor is pointing to the #1 mark. It's more of a cosmetic thing that you want the BOSCH name plate facing the rear, since that's the way the factory installed it, but from a purely mechanical point of vies... it doesn't matter.

[Barry Brisco]

I presume the TDC is the mark in the middle of OT??? When should the light go on? Is it 3 degrees towards the O or 3 degrees towards the T? In my opinion above the T because the light should go on before passing TDC but I would like to make sure.

Joost, the article at http://356registry.org/tech/ignition_tune.html by Ron LaDow explains pretty clearly how to time your car. Follow it step by step and I think you will understand. Post again if you have questions.

[Guest]

Joost:
The light should come on when the engine is at 3-5 degress BTDC. Since the crankshaft rotates clockwise when viewed from the back of the car, this will be to the RIGHT of the TDC mark, about a 1/4 inch.

[Joost van der Velden]

I am sorry but I still don't know where "Before TDC" mark is. Is it 3 degrees to the right or 3 degrees to the left (from the OT mark which is in the middle)?

[Michael Eker]

Using a timing light the OT mark should be illuminated 3.6mm to the left of the crankcase

join.

If the engine is stationary the points should open 3.6mm before the OT mark is at TDC.

The engine runs clockwise.

meker

[Glenn Ring]

Print this and use it to mark your crank pulley.

[Joost van der Velden]

Using a timing light the OT mark should be illuminated 3.6mm to the left of the crankcase

join.

If the engine is stationary the points should open 3.6mm before the OT mark is at TDC.

The engine runs clockwise.

meker

I think and I also get replies that is is to the right when standing behind the car and looking at the engine......

The pulley runs clockwise so before it gets to the TDC it will first run by the "T" so that means to the right of OT.

Or am I thinking wrongly?

[Joost van der Velden]

Print this and use it to mark your crank pulley.

Thanks! This will be helpfull and shows also where to look for the BTDC mark.......

[Michael Eker]

Think of it like this.

Once the spark has ignited the fuel it takes time for all the fuel to burn.

At idle Porsche say this takes the time the crankshaft turns through 3 degrees.

So you need to ADVANCE the spark before top dead centre, or OT on your pulley.

( the spark occurs when the points open and your timing lamp comes on)

Over about 3000 rpm Porsche say the spark has to be 30 degrees in advance of TDC.

You could set the timing at 3000 rpm and 30 degrees advance and just let the idle timing

fall wherever.

In fact as Porsche published this data based on 1960s German gasoline which bears no

resemblance to that available today this is probably your best plan.

If you don't have a timing light,

( they are very inexpensive http://www.pvrdirect.co.uk/productinfo. ... tref=52616)

You will need to set the static timing at 3 degrees before TDC.

meker

[John Clarke]

Hi Joost.

I think that timing at the crank at 3000 rpm is the way to go. Personally I think that with the modern fuels that the ignition should be set at NO MORE than 32 degrees, and NOT at 35, you don't want burnt pistons!
Glenns protractor for marking the degrees on the pulley is a good idea.( I shall print one of these off, Thanks Glenn ). Mark off 32 degrees on the front of the pulley rim, accurately cut a small "V" notch and mark with white marker paint ( sold in roller ball type dispensers)
Hook up your timing lamp and run at 3000 rpm on the rev counter / Tacho and adjust the dizzy to the mark. If your centrifugal advance mechanism in the dizzy is O.K . the tickover should be fine . If not just speed up the tickover equally on both carbs.

Keep the Faith

Jay Cee