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Crotchety Old Bastard
 
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There is no reason for confusion other than getting so far away from the original question as posted. Simply follow the factory manual procedures and call it a day. Mark's distributor is an early 3.3L Euro with the same part number as the one I use.

Moonie's dizzy must work fine or he would have had problems by now. Only his mechanic knows for sure what was done an he is the one to ask questions to, anything else is pure speculation.

The late model distributors that have vac advance are timed the same as the Euro at 4000rpm; they too work using mechanical advance on boost. This function allows for more advance during cruise which is lost when vac goes away. This is covered in the manual for that year. Don't speculate, run the part numbers to see what you have and follow the manual.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 04-01-2010, 07:32 AM
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sudo apt-get purge 930
 
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Quote:
Originally Posted by RarlyL8 View Post
There is no reason for confusion other than getting so far away from the original question as posted. Simply follow the factory manual procedures and call it a day. Mark's distributor is an early 3.3L Euro with the same part number as the one I use.

Moonie's dizzy must work fine or he would have had problems by now. Only his mechanic knows for sure what was done an he is the one to ask questions to, anything else is pure speculation.

The late model distributors that have vac advance are timed the same as the Euro at 4000rpm; they too work using mechanical advance on boost. This function allows for more advance during cruise which is lost when vac goes away. This is covered in the manual for that year. Don't speculate, run the part numbers to see what you have and follow the manual.
I agree this is getting too deep for my simple mind and my XDI comment started another debate that would be good for another thread.
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Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***

"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"
--clutch-monkey
Old 04-01-2010, 07:40 AM
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fredmeister

For referance the 91-94 C2 turbos run 21 deg +/-3 deg depending on intake temp. That could be -18 to -21 or -24. No one has verified if they will go past 21 deg under hot intake temps.

Dave,

Good suggestion on a rebuild. Andial used to offer a performance rebuild for the 930's and might be someone to concider as they probably knew these cars better than most at one time. They also want the pressure box (pot) as I believe them modify its stop.
Old 04-01-2010, 07:49 AM
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Quote:
Originally Posted by 911st View Post
Roland,

So the pic of the single pressure box is from a 3.0 turbo? Anyone have a 3.3 single box distributor?
Mine is a 3.3l with intercooler

...and it's the same distributor on every 4-speed turbo 930 from '78 on (Euro)

Quote:
Originally Posted by e170drvr View Post
So a late model euro cvs turning dizzy only has vac retard
No, vac retard and centrifugal advance, see charts earlier in this thread
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Roland

930 Turbo '81 Too many modifications to list

Last edited by proffighter; 04-01-2010 at 02:00 PM.. Reason: additional info
Old 04-01-2010, 01:56 PM
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Quote:
Originally Posted by RarlyL8 View Post
...The late model distributors that have vac advance are timed the same as the Euro at 4000rpm; they too work using mechanical advance on boost. This function allows for more advance during cruise which is lost when vac goes away. This is covered in the manual for that year. Don't speculate, run the part numbers to see what you have and follow the manual.
Are you sure. I did not think any of the 3.3 distributors had "vac advance", only 'Vac-retard'. Especially the dual pot type so this it new info I am thinking. Or can you elaborate, post, or forward me that section please?

It dose not seem like any of the 3.3 distributors had 'Vac-Advance' thought I have long suspected the single box style did only to be told this is not the case.

Appreciated.
Old 04-01-2010, 02:48 PM
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Roland,

Thank you.

Then the two pictures seem accurate for the two main 3.3 style distributors.

The retard pots enter on opposite sides of the dist. The twin pot pushes, the single pot looks to pull against the dizy's internal plate.

Both dizy's we are told rotate the same directions.

The dual pot Vac-retard/Boost-retard pushes. The single pot Vac-Retard pulls.

If this is correct then my thoughts about Mooney's modified dist may have some merit and are at least worth looking into of verifying just to be safe.

I would think a Vac-Retard pot from an SC would have been a better choice if the 930 single is NLA. However, I do not know how much retard it has.
Old 04-01-2010, 03:01 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #66 (permalink)
sudo apt-get purge 930
 
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I bought a hand vacuum/pressure pump today and if things works out I'll measure timing at 500 rpm increments with the hose connected and disconnected. I will also note the direction the pot moves the ring under vacuum and if it moves it under pressure. I think we'll find that my observation will match the factory manual.
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Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***

"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"
--clutch-monkey
Old 04-01-2010, 03:21 PM
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Cool!!!
Old 04-01-2010, 03:24 PM
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This is a standard European distributor.

This distributor rotates counter clockwise.

It is connected to the correct port on the throttle body.

There is no vacuum at idle supplied to the distributor.

This distributor has the control arm attached to the left, which allows for vacuum retard. Most US distributors have the control arm attached to the right (see diagram below).

The correct timing for this distributor is 0 + or - 2 degrees AT 1000 RPM with the hose connected.

The maximum timing under boost is 2 (static) + 0 (vacuum or boost) + 12 centrifugal = 14 crank degrees.

UNDER NO CIRCUMSTANCES SHOULD THIS DISTRIBUTOR EVER BE TIMED OR "LOCKED DOWN" TO 26 DEGREES AT 4000 RPM. THIS WILL BE THE TIMING YOU HAVE UNDER BOOST!!!!




Quote:
Originally Posted by equality72521 View Post
Ok Speedy, here is the best I can get without pulling it apart and I'm not doing that until the weekend. It's too nice out not to drive it.

It looks like the numbers are 0 237 301 00 and PGFUDB

Old 04-01-2010, 04:22 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #69 (permalink)
sudo apt-get purge 930
 
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Quote:
Originally Posted by Speedy Squirrel View Post
UNDER NO CIRCUMSTANCES SHOULD THIS DISTRIBUTOR EVER BE TIMED OR "LOCKED DOWN" TO 26 DEGREES AT 4000 RPM. THIS WILL BE THE TIMING YOU HAVE UNDER BOOST!!!!
I'm confused. The factory manual clearly states, in no uncertain terms, that idle for R.O.W. cars is to be set at 29 BTDC @4000RPM with vacuum hose disconnected.


Directly from the manual:


ADJUSTING IGNITION TIMING FROM 1978 MODELS


Adjusting Values:
Europe. R.o.W.
29 before TDC at 4000 rpm

Europe version requires the detachment of vacuum
hose at distributor. It remains connected for USA,
California and Japan versions.
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Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***

"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"
--clutch-monkey
Old 04-01-2010, 05:00 PM
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Wait, I made a mistake.

There IS vacuum supplied at idle.

This makes the total maximumtiming under boost 10 (static) + 0 (vacuum or boost) + 12 centrifugal = 22 MAXIMUM.

Quote:
Originally Posted by Speedy Squirrel View Post
This is a standard European distributor.

This distributor rotates counter clockwise.

It is connected to the correct port on the throttle body.

There is no vacuum at idle supplied to the distributor.

This distributor has the control arm attached to the left, which allows for vacuum retard. Most US distributors have the control arm attached to the right (see diagram below).

The correct timing for this distributor is 0 + or - 2 degrees AT 1000 RPM with the hose connected.

The maximum timing under boost is 2 (static) + 0 (vacuum or boost) + 12 centrifugal = 14 crank degrees.

UNDER NO CIRCUMSTANCES SHOULD THIS DISTRIBUTOR EVER BE TIMED OR "LOCKED DOWN" TO 26 DEGREES AT 4000 RPM. THIS WILL BE THE TIMING YOU HAVE UNDER BOOST!!!!

Old 04-01-2010, 05:01 PM
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Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***

"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"
--clutch-monkey
Old 04-01-2010, 05:08 PM
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does anyone know where i can purchase a "single vacuum retard pot" for my distributer?

or, are they just not available any more?
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Old 04-01-2010, 05:14 PM
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Porsche still has them. Here is a non-porsche version for sale:

Aircooled.Net, Inc. - Online Autoparts Catalog

I would test the non-porsche one to make sure it is working correctly.

Quote:
Originally Posted by mooney265 View Post
does anyone know where i can purchase a "single vacuum retard pot" for my distributer?

or, are they just not available any more?
Old 04-01-2010, 05:49 PM
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Quote:
Originally Posted by Speedy Squirrel View Post
Porsche still has them. Here is a non-porsche version for sale:

Aircooled.Net, Inc. - Online Autoparts Catalog

I would test the non-porsche one to make sure it is working correctly.
If i read it correctly, they only offer "advance only" or "advance/retard." but, not a "retard only??"
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LIVN80S - - Red '79 Porsche 930 Steel Slant Nose Conversion [in 1987] w. 46k miles 3.3L; 964 Cams; K27HF @ 1.0 BAR, with Garrettson Intercooler; Rarly Zork; CIS Flowtech Fuel Head & BL-WUR.
Old 04-01-2010, 05:54 PM
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The advance only, when flipped over to the other side becomes a retard only. See my apparently crappy diagram above. The top shows the left side retard configuration. The bottom two show the right side advance configuration. If the rod pulls on the left side it is retard only. If it pulls on the right it is advance only, for counterclockwise distributors.

Quote:
Originally Posted by mooney265 View Post
If i read it correctly, they only offer "advance only" or "advance/retard." but, not a "retard only??"
Old 04-01-2010, 06:10 PM
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Crotchety Old Bastard
 
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Quote:
Adjusting Values:
Europe. R.o.W.
29 before TDC at 4000 rpm
Mark, you may see in the notes I sent you that I lock my distributor, which is the same as yours, down at 26* @4000rpm. The reason for this and not 29* is so I can safely use poor grade gasoline in the hot summer. I made the assumption that the specification of 29* in my 1978 manual was for European grade fuel available to the public in 1978. I have never had an issue with detonation and my engine is very healthy after 10 years of flogging the crap out of it.
Just follow what it sais in the manual and you will be good to go.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 04-01-2010, 06:21 PM
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Sweathogs unite!

Bottom line is that when you take the vacuum line off at idle the timing will advance about 10 degrees more than with it on. If you were timed at the factory spec of 0 + or - 2 with it on at idle, it will be 10 + or - 2 with it off, and it will have a maximum of around 22 under boost, which Porsche considers safe for a stock 930. I think you will notice that it drives a little better with it off.

Quote:
Originally Posted by equality72521 View Post
Old 04-01-2010, 07:22 PM
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Thanks much Speedy Squirrel

Good work on the drawings and thank you for confirming how the retard works on the different distributors. It helps me believe that I am on the right track on this stuff after all the effort we have put in on this topic.

Brian's running 26 deg on boost with no retard is a good data point. He dose have a more efficient intercooler, turbo, and is only running .75 bar. I do not know if one could run 1 bar on Calif fuel and get away with that at 100 deg day after sitting at a stop lite for several minutes with the A/C on. The factory has to build in room for this.

It is possible that if we are watching our EGT's and AFR's we might get away with a lot more aggressive ignition timing. There are clues out there that indicate these might be possible.

If Brian can run 26 deg with not boost retard then a properly working US dist might be able to run 34 deg and then pull back to about -25 on boost. Remember, the C2 turbo runs 40 deg under light load at cruse.

I am not saying we can, just that it might be possible.

Good work so far everyone.

Just a thought.
Another data point is the C2 turbo that runs 21 +/- deg timing depending on intake air temps.

It still amazes me that euro's do not seem to have any boost retard.

I see little issue with running without Vac-Retard on a 930, euro or US, as it is more for emissions.

I wish someone that knows how to program a turbo on a dyno would test at different advance levels and see where we make the most power. That is the only way to see how much advance we can run. Of course we would want to pull it back a bit to stay safe under varying conditions.
Old 04-01-2010, 08:49 PM
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Quote:
Originally Posted by 911st View Post
It still amazes me that euro's do not seem to have any boost retard.
Which still begs the question, why not US also? Surely not emissions related. I won't be comfortable with this until the answer is clear.
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Old 04-02-2010, 04:43 AM
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