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Timing setting for high boost?
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2595
Location: MI

PostPosted: Tue Jun 30, 2015 2:29 am    Post subject: Timing setting for high boost? Reply with quote

80 931..

I'm going to the speed shop in about 2 hours to get my timing set up/confirmed because they have the tools and I don't.. I want to make sure my timing is correct before I start raising boost..

Should I run my timing a bit retarded if I'm planning on raising boost above stock levels for a safety net? How much?

If no one answers before I go I'll just set to factory spec.. Any advice?
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ideola  



Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI

PostPosted: Tue Jun 30, 2015 2:41 am    Post subject: Reply with quote

I have run up to 15 psi of boost on my "941" using factory ignition system. The car is not exactly stock (8.3:1 CR diamond pistons with Crower long rods, ported head, and water-meth injection for intercooling). I typically leave the boost controller set to 11-12 psi, but on really cold or wet days have turned it up to 15 psi with no ill effects or audible pinging.

I firmly believe the car would benefit from additional ignition tuning, but the stock system has been rock solid with almost two full seasons of driving.

YMMV.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2595
Location: MI

PostPosted: Tue Jun 30, 2015 3:14 am    Post subject: Reply with quote

So do I do what haynes says or what?

haynes says...

"turbo models"

"20 deg btdc @ 2000 +- 50 with vac lines attached"

"Timing mark -20"


and..

3-9 deg btdc at 900 idle.. lines connected..

and..

250 mbar Vacuum applied to connection 1 of disributor (or link both ports to intake vacuum?)..

idle should raise and advance should be 32-38 deg btdc..



Or the 924board way of doing it??

remove and plug vac lines..

10 deg btdc at idle?

Is haynes correct and I can just do it that way + the control tests or what?

Very confusing..

Haynes is correct that the "timing mark" is -20 deg or 20 deg btdc?
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ideola  



Joined: 01 Oct 2004
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Location: Spring Lake MI

PostPosted: Tue Jun 30, 2015 3:39 am    Post subject: Reply with quote

Pretty certain I have my 80s all set to 20 deg btdc as per the instructions on the decal on the fender. I suspect that Haynes' instructions are a reasonable fascimile thereof.

If you're missing the decal, have a look at this thread:
http://www.924board.org/viewtopic.php?t=22954

I can't point you to the correct post in that thread because my company's firewall filters out most of the images, but pretty sure there is an S1 931 decal in there somewhere. That's what I would rely on rather than Haynes or some random posting on the forum.

Which leads to this question: where are you getting the 10 deg as "the 924board way" of doing it?
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ideola  



Joined: 01 Oct 2004
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PostPosted: Tue Jun 30, 2015 3:46 am    Post subject: Reply with quote

Actually, my own post on the second page shows the correct procedure. The photo is actually from the 941 before I converted it to 944 expansion tank.
http://www.924board.org/viewtopic.php?p=249514#249514

From 941 (originally a 1980 931).




So notice the instruction column. You should remove and plug the vac lines BEFORE checking timing. On a fully warmed up car, set to 20 degrees BTDC +/- 1 degree at 2000 RPM. Then reconnect the vac lines.

The additional tests in Haynes are to confirm that the advance/retard is functioning correctly.
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Fasteddie313  



Joined: 29 Sep 2013
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PostPosted: Tue Jun 30, 2015 3:52 am    Post subject: Reply with quote

ideola wrote:

Which leads to this question: where are you getting the 10 deg as "the 924board way" of doing it?


IDK because I see so many different recommendations I'm all confused..

Haynes doesn't say anything about removing the vac lines for idle timing setting but thats what I read here, remove/plug vac lines 10 deg btdc at idle 900..

rather haynes says 3-9 btdc with hoses attached as a check, at idle 900..

but to set to -20 at 2000 rpm with hoses attached..

I'll go look at the sticker, forgot about that thing..

sticker = + more confusion..

it says -20 deg at 2000 rpm like haynes says but the sticker says with the vac lines off and plugged while the haynes doesnt say to remove them..

haynes says "leave vac lines connected unless otherwise stated in the spec section"

haynes spec section does NOT say to remove the vac lines for 2000 rpm -20 deg setting..

the sticker on the car says remove/plug them, haynes says do not remove/plug them, both for 2000 rpm -20 degree..
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Fasteddie313  



Joined: 29 Sep 2013
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PostPosted: Tue Jun 30, 2015 3:56 am    Post subject: Reply with quote

Actually haynes says to remove and plug the lines on ALL models BUT turbo models in the specifications section..
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ideola  



Joined: 01 Oct 2004
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PostPosted: Tue Jun 30, 2015 4:08 am    Post subject: Reply with quote

Haynes is near-useless for turbo-specific instruction.

Use the instructions I posted above from the sticker. It's easy. Don't over-complicate things. Warm up the car. Turn it off. Remove the fact lines to the dizzy and plug them. Start the car. Bring up to 2000 RPM. Set timing to 20 BTDC. Turn car off. Reconnect vac lines.

Done.
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Cedric  



Joined: 27 Aug 2004
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PostPosted: Tue Jun 30, 2015 5:19 am    Post subject: Reply with quote

To set this straight I here give you the Porsche factory service manual with all the info you need to have!

http://www.equipedic.se/docs/924/assembly/Porsche%20924%20Turbo%20Assembly%20and%20Adjusting%20Instructions%201980%20MY.pdf

from page 35.

Have a nice day and I hope you can turn the boost up soon
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2595
Location: MI

PostPosted: Tue Jun 30, 2015 6:15 am    Post subject: Reply with quote

That was a total fail...

I guess I have to buy a timing light, if I want something done right I have to do it myself.. Like usual.. No changes were made...
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ideola  



Joined: 01 Oct 2004
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PostPosted: Tue Jun 30, 2015 6:25 am    Post subject: Reply with quote

Fasteddie313 wrote:
That was a total fail...

I guess I have to buy a timing light, if I want something done right I have to do it myself.. Like usual.. No changes were made...


Sorry, know that frustration. You can get an adequate timing light for $35 at Autozone or other FLAPS. Indispensable tool.
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Tue Jun 30, 2015 6:38 am    Post subject: Reply with quote

Cédric wrote:
To set this straight I here give you the Porsche factory service manual with all the info you need to have!

http://www.equipedic.se/docs/924/assembly/Porsche%20924%20Turbo%20Assembly%20and%20Adjusting%20Instructions%201980%20MY.pdf



Thank you... Bookmarked and reading..

BTW the boost will be a while, The pieces required are a week out at best..
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Last edited by Fasteddie313 on Tue Jun 30, 2015 8:11 am; edited 1 time in total
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2595
Location: MI

PostPosted: Tue Jun 30, 2015 7:51 am    Post subject: Reply with quote

ideola wrote:

Sorry, know that frustration. You can get an adequate timing light for $35 at Autozone or other FLAPS. Indispensable tool.


I will, and now I am clear on the -20 @ 2000 rpm setting procedure with lines removed and plugged as well.. I was planning to use the haynes as the reference at the shop, good thing it didn't work out that way..
Thank both of you two..

Would I be correct to say that I would NOT need an advancing timing light to set to -20 at 2000 rpm but WOULD need an advancing timing light to confirm 3-9 @ 900 and 32-38 at idle with artificial vacuum pulled to the distributor?

Something like, shoot the light with the engine running at specification, adjust advance on the light until I find a mark, then calculate actual current advance by timing light setting vs the mark I found?
Subtract the timing light setting from the found mark = actual advance?

How do you know if your 3-9 or 32-38 otherwise?

Or maybe just disregard the test procedures?
If the distributor wasn't mechanically advancing correctly would there be symptoms or just enough to blow me up? It would likely fail to the safe retarded position no?
It's not like I've ever witnessed a known sorted 931 to compare, my timing could be all crazy and I may know no different, ie make sure before cranking boost..
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ideola  



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PostPosted: Tue Jun 30, 2015 1:02 pm    Post subject: Reply with quote

I think the advance/retard is either going to work or not. If you plug the lines together as suggested in FSM, and you get the racing idle, there's a really good chance everything is working fine. About the only thing to fail is the vac diaphragm attached to the dizzy, and if it leaks, you won't get advance/retard. Honestly, I've never bothered (or found a need) to check the advance retard on any of my S1 cars. In my experience, the system is pretty foolproof. Set the timing to 20 BTDC and call it a day.
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Fasteddie313  



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PostPosted: Tue Jun 30, 2015 1:22 pm    Post subject: Reply with quote

I like your answer, less expensive/easier to find timing light, and less work for me..

Thanks again
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