snakepitt1

I have a 1973 911T with the 2.4L MFI motor. My timing is retarded quite a bit causing excessive exhaust temperatures and causing very high oil temps too. I have never messed with the timing on a Porsche, but, I have done so on American vehicles. I understand that the timing should be set at 35 degrees at 5 or 6000 RPM. What is the proper procedure for changing the timing and getting it back where it needs to be. The car is hard to start and has a brand new optima battery.
Thanks,
Scott Harris

Steve Weiner-Rennsport Systems

Hi Scott:

Getting your timing up to factory spec will really wake up your car and its pretty simple to do if you have done the same on other makes.

First, you'll want to locate and mark the 35 deg mark on the crank pulley so you can see it easily. I use a yellow tire marking stick, but you can use what you have.

Next, connect you timing light to the #1 plug lead and power it from the left-side mounted fuse panel.

Now, start the engine and get it up to temperature, if its not already. You are going to quickly rev it to 5K RPM.

Now,...using a 13mm socket, 6" extension and ratchet handle, loosen the nut a bit that holds the distributor.

OK,....now the fun part,... Bearing in mind that CW advances timing and CCW retards it, quickly rev the motor to 5K and observe the timing marks to see where your 35 deg mark in relation to the TDC mark on the fan housing.

At idle, move the distributor slightly in the direction you need and rev the motor again while watching the marks to see where you are at. Correct as necessary.

After you have it set, tighten the distributor hold-down nut and recheck timing.

Voila'....done!

snakepitt1

Steve,
Thank you for the information.
What about disconnecting and plugging the vaccuum lines during timing changes? What about timing at idle? I received an e-mail from pelican parts about this same question and Bob informs me that I should not set up my timing at 5K RPM but only at idle. Your advice is opposite his. Should I do both?
Will properly set timing reduce my exhaust temperatures and with those temperatures lowered, lower my oil temperature issue? The nearest Porsche repair shop is in Memphis, TN over 2 1/2 hours away. Plus I would rather work on my own car when ever possible.
The weather is nice now and I need to pop the targa off and drive through the TN and KY mountain roads.
Thanks,
Scott Harris

Steve Weiner-Rennsport Systems

Hi Scott:

I cannot advise you who to believe on subjects like this; that is something you must decide for yourself. Its a credibility issue,...

It matters little what the timing is at idle. Set the timing with the vacuum lines disconnected at 5K RPM to 35-36 deg total. Don't bother to plug them as it won't matter for what you are doing.

You should see about 5 deg ATDC with the hoses connected at 950 RPM.

Noel

To help out with the credibility issue. Steve has more experience with these cars than anyone. Based on my years on this board, you can trust him. In fact, I am printing this thread out to keep in my technical archive binder for when I next set or check my timing.

snakepitt1

Steve,
Is there an actual 35 degree mark on the crank pully? How is it marked?
By the way, thank you for advice. Very professional and well written. It helps knowing that guys like you take the time to help those of us trying to work on our own cars.
Thanks,
Scott Harris

Lorenfb

The key point, which has been implied, is that the vacuum doesn't matter at
the critical load points for max timing, as max timing affects detonation at
those points.

Steve Weiner-Rennsport Systems

Hi Scott:


Loren is right; max timing does indeed affect the threshold of detonation,...

Now,....looking at your crank pulley, you will see several marks (notches) on the outer (rear) side of the sheave. There will only be one little notch on the inner side (engine) of the sheave; that is Z1 or Top Dead Center for cylinder #1. This marker is the only one that is notched on both sides so one can ID which one is Z1.

Looking to the right of Z1 (#1 TDC), you will see two other marks and the one furthest away from Z1 will be the 35 deg mark.

Mark that one with white or yellow paint,...I've also used my wife's fingernail polish. You don't need to share that,...

Voila',...Now you are ready to time the motor.

art

I made the earlier suggestion that your timing MAY be excessively retarded which was causing your high exhaust temps. It may not be, so check it first with a timing light.

joel_in_raleigh

sorry to dig this old thread up...just want to clarify a point on the timing light

So basically any timing light will do both the idle and high-rpm timing; since the pulley is marked for Z1 and 35deg there is no need for an advance timing light? Have I got this right?

Steve Weiner-Rennsport Systems

Hi Joel:

Yessir, any timing light will do. The dial-back ones just make the task easier.

DGaunt

Two words: Believe Steve.

Steve, I thought you set the timing @ 6,000 RPM. at least on my '76. Is that wrong?

Steve Weiner-Rennsport Systems

Hi Dave:

The RPM point I use to set timing depends on how much centrifugal advance is in each distributor.

In some cases, its all in by 4K so there is no point in running it to 6K. Others are all in by 5K so that the point where I confirm and adjust total timing.

My timing light (Snap-On) has a tach as well as advance functions so I take note of the engine speed where it stops advancing.

In the case of your '76, all of the centrifugal advance is in by 4500 so I'd set it at 5K, maximum. There is no point spinning it to 6K,....

BoyT-911

Steve W.,

For 1978 SC cars, what engine rpm do you set the timing? Thanks.

TD

Steve Weiner-Rennsport Systems

TD:

I check those at 5000-5500 RPM. Make sure that the vacuum line is disconnected from the distributor and plugged off.