Idle Timing EURO SC

[Vereeken]

Could someone confirm the following I have found for 911 SC Euro?

Idle timing: 5deg BTDC vacuum disconnected. I only have advance not retard going to dizzy.

Timing at 4000 rpm: 33deg

The problem I have is that my pulley has only two markings and nothing written on them. They are about 3 cm apart.
I was expecting to find Z1 (top dead center) about half a centimer to the right a second one (5 BTDC) and a third one about 3 cm to the right of the first one.
But I only have two markings and nothing else. Can I assume the first is TDC and the second is 33 deg BTDC?

I have a strobe light and i feel that the car runs best with 5 deg BTDC (at least if the mark I see is Z1) I see the timing move to the extreme right one when accelarting but I can not see how many RPM I am making when I am doing this as my head is stuck in the compartment trying to read the timing and manipulating the throttle linkage.

Am I doing OK (on the timing ofcourse).

Thx

Michel

[psalt]

Michel,

Idle timing is less important than high speed advance. What year is your car ? I don't see a 33 degree spec, 82-83 SC ROW is NOT ABOVE 25 BTDC (Porsche spec book).

The pulleys do not have a full advance mark, just TDC (Z1) and 5 BTDC. You need an advance timing light or measure the pulley and make a mark at 25 BTDC. Set the high speed advance and let the idle timing fall where it does. If you wind up with more than 5 BTDC, your springs are worn.

[Vereeken]

Originally Posted by psalt

Michel,

Idle timing is less important than high speed advance. What year is your car ? I don't see a 33 degree spec, 82-83 SC ROW is NOT ABOVE 25 BTDC (Porsche spec book).

The pulleys do not have a full advance mark, just TDC (Z1) and 5 BTDC. You need an advance timing light or measure the pulley and make a mark at 25 BTDC. Set the high speed advance and let the idle timing fall where it does. If you wind up with more than 5 BTDC, your springs are worn.

The car is 1982 (end). EURO no O2 sensor, only advance on distributor.
I have two marks on the pulley. I shall measure them but they are 2 to 3 cm apart. So I guess I will find 25mm between one and two if you believe 25 BTDC is the high speed idle setting. I understand taht 1 mm is about 1 degree.
Can you tell me what the Porsche spec book says on when 25BTDC should be reached? At 4000 RPM?

Thanks

Michel

[psalt]

Michel,

The marks on the pulley are TDC (Z1) and 5 BTDC, not full advance. The mark you need to make should be around 27 mm from TDC with the stock A/C pulley.

The Porsche spec book say 25 BTDC @ 4000 rpm and not above 25 BTDC @ 6000 rpm.

[Vereeken]

Originally Posted by psalt

Michel,

The marks on the pulley are TDC (Z1) and 5 BTDC, not full advance. The mark you need to make should be around 27 mm from TDC with the stock A/C pulley.

The Porsche spec book say 25 BTDC @ 4000 rpm and not above 25 BTDC @ 6000 rpm.

Damn. I wonder what is going on. Can it be that I aligned my timing with the piston 180 degrees opposite teh number 1 piston?
The car starts fine runs great once warm no hesitation only a slight stumble around 2800rpm pulls nice all the way through the rpm range AFR is around 14 which = about 2% CO.

Can this be possible totally timed on the complete opposite cillinder?

I am going to inspect the pulley see if I find other marks and am going to reset number 1 to TDC that should bring the correct mark to the front I guess.

I assume I have to work as if timing is completely lost.

Michel

[dede911]

Hi Michel,

I to have a 82 euro 911SC . 33deg total advance is definitely to high and can cause detonation.

Porsche spec for this type is 25deg @4000rpm

I set mine at 27deg, what is OK for our fuel quality (super 98).

The 5deg at idle is only a baseline to get the car started after a retune. Once the cat is warmed up, set it to 25-27deg at 4000rpm and job done.
To do this properly you need an adjustable timing light.

Be careful with the "afr 14 is around 2%co" conclusion.I don't trust this...don't ask how I know...
Have the car checked on a 4 gas analyzer.

Last time I had the CIS tuned (and ign ckecked) by a pro for very little money..;

Ther is on the Pelican forum a very noce thread from Gunther about servicing the distributor

By the way, where are you located in Belgium?

André

[Vereeken]

I am in Leuven.

I did the Gunter Distributor overhaul two weeks ago. Dizzy is fine. I am fairly confident on the CO I have a CO analyser as well. Also there is no hunting at idle wich is a sign that i am within spec. I will set to 25 at 4000rpm but what strikes me most is that I think I am looking at the wrong pulley markings and still get the car to run OK. I understand that you can find up to four markings. I am going to try to find TDC at cilinder one and see which marking comes up set the dizzy, start, warm-up and then set the 25 at 4000. Just a tad worried about screwing out the spark plug.

Michel

[euro911sc]

I'll check, but I swear that there is only one extra mark on my ROW SC no ac pully... one just clockwise of Z1, about 3 cm on the perimeter, which has 25 just under the mark. When I set my dist. up I made it so I hit that mark at 4k... To set idle I had to measure the perimeter and divide by 5, then ink it... kinda a pain.

-Michael

[Vereeken]

Originally Posted by euro911sc

I'll check, but I swear that there is only one extra mark on my ROW SC no ac pully... one just clockwise of Z1, about 3 cm on the perimeter, which has 25 just under the mark. When I set my dist. up I made it so I hit that mark at 4k... To set idle I had to measure the perimeter and divide by 5, then ink it... kinda a pain.

-Michael

That is what I would have expected as well, but I swear at least 3 markings. Could it be this has someting to do with teh fact that my SC was one of the very last of the line? I have bumpers, fog lights etc like the carrera and they where on straight from the factory... i will try to take pictures this week.

[Gunter]

When the pulley is showing Z1 with the distributor rotor pointing to the notch in the housing, the #1 cylinder could be at either compression- or exhaust stroke.
To be sure, set the pulley to Z1 (TDC), open the cap, rotor points to the notch.
Remove the left top valve cover and wiggle the rocker on intake valve #1; it should be loose because of the 0.1 mm clearance.
If it is tight, you're at the exhaust stroke and need to turn the engine cw 180 deg to Z1; now the rocker should be loose.
A way to confirm Z1 is to remove the plug on #1, insert a chopstick into the hole, turn the engine slowly cw and watch the stick; when it stops moving Z1 on the pulley should be very close to the center (Case seam)

If you're worried about removing the plug from a hot engine, remove the plug for #1 with engine cold, use a small amount of Anti-seize, re-torque to just half of the normal 20 ft-lbs for the short duration of testing for TDC and tighten it to the correct torque when you're finished checking/testing.

If there are no markings on the pulleys for RoW or Euro 911, how do you set the valve clearances?????
US 911's have markings every 120 deg for that on the pulley.
Z1 is TDC and 5mm to the right is the 5 deg BTDC-mark to set timing for idle.

So, how do you set valves on Euros without markings??????

[Head416]

I think when he says there are no other marks he means in that area. My RoW definitely has the marks every 120.

[Vereeken]

Originally Posted by Head416

I think when he says there are no other marks he means in that area. My RoW definitely has the marks every 120.

Yep that sums up my problem. I have two markings on my pulley and none of them says Z1 as far as I can see. They atcually say nothing just 2 notches in the pulley.
The two markings I have are roughly 30mm from each other and when I set Idle at 5 degrees to right of first marking then give 4000 RPM the timing moves to the second mark and stays firmly there even at 6000 RPM so all in all you could say that the dizzy does what is supposed to do and that I timed correctly.
If i had timings every 120 I should at least find 2 more and that is not the case.
I will dismantle and go out and find actual Z1 the chopstick way.

So to my second question. can it be that I timed the engine on the basis of a wrong cilinder and still get a good running engine?

I will try to take pictures and explain the problem more in depth. I want to understand this. All in all this is basic engine tuning.

Thank you for all teh help so far.

Michel

[psalt]

Hello Michel,

This may be a ROW vs US difference. On US cars, TDC (Z1) is a double notch filed in both sides of the pulley. The 5 BTDC idle timing notch is a single notch. The factory spec book has no idle timing spec for the ROW engine, just 25 BTDC @ 4000 rpm, so maybe the pulleys are differently marked.

[don gilbert]

mike, to get the most out of your advance, esp. if you made mods to exhaust,fuel or intake, the factory spec are no good, the old hot rod trick is to advance until u hear pinging, and then back it off a bit,differnt grades of fuel make a huge differences, the factory spec are not optimal for max perf. even on a stock engine, i recomend using 93 octane, advance as far as u can go without pinging

[Vereeken]

Originally Posted by don gilbert

mike, to get the most out of your advance, esp. if you made mods to exhaust,fuel or intake, the factory spec are no good, the old hot rod trick is to advance until u hear pinging, and then back it off a bit,differnt grades of fuel make a huge differences, the factory spec are not optimal for max perf. even on a stock engine, i recomend using 93 octane, advance as far as u can go without pinging

That should not be an issue over here. We have got 95 as a minimum but I always load on 98. I never heard any pinging on any of my cars I only have a description on how it should sound.

Michel

[moneymanager]

In my experience you can't time the motor on the wrong cylinder and get anything like normal performance. Having screwed this up several times, I am pretty sure you will not be able to get the car to run at all, or if it does, it will sound like it has thrown a rod. This from someone who once adjusted all his valves backwards. Amazingly, the car ran, barely.

[Vereeken]

Ahah. an experience answer ;o)

[MBEngineering]

HI Michel
which "ROW" pulley do you have??









this is the part No' of the above pulley


and the info for your timing and fuel.


regards mike

[Vereeken]

MBengineering (and others).

I looked and compared to you pictures. I have the last pulley . With a mirror I was able to see two markings when number one was at TDC.
I thought it said Z1 and Z5 but looking at your picture I think it is Z1 and 2 5 .
The two are about 2.5cm apart. So If I am right Z1 is TDC and 25 is 25degrees before TDC the point I have to set at a certain rpm for my model range.

It is more clear to me now. I had timed at number one but always timed on idle 5 degrees. Clearly this is indeed not the way caus I have set timing now at 25 at 4000 RPM and the car runs smoother then before. Why we need idle timing at all is a mystery to me.

Next step is to fine tune the mix.

So I guess if I will set my timing at 27 at 4000RPM given that I run 98 octane and set my mix to 3% CO. I believe from what I read that would give me maxium performance with maximum smoothness.

Michel

[Gunter]

Sounds good to me.