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-   -   Advance Wrong--What to look for? (http://forums.pelicanparts.com/porsche-911-technical-forum/438690-advance-wrong-what-look.html)

Paulporsche 10-31-2008 01:14 PM

Advance Wrong--What to look for?
 
A mechanic who was recently working on my car said I am getting full advance @ 2000 rpm. I understand this should not happen until about 3500 to 4000.

If I open up the diz what should I be looking for? Broken springs? Dislocated weights?

I should be able to see a broken spring or a weight that has come loose. What else could cause this? Can I tell by look or feel if something is worn or fatigued?

Steve@Rennsport 10-31-2008 01:44 PM

Paul,

You should look for a broken or missing spring on one of the weights.

Remember, there are two springs in these things: one is a light spring and the other is stiffer. Both are required for proper operation.

Paulporsche 10-31-2008 07:11 PM

Thanks, Steve.

If springs are intact, is there anything else that could cause this?

Is there any reason why someone would deliberately ramp up the advance this quickly?

moneymanager 10-31-2008 07:48 PM

Not if his brain was intact!

Steve@Rennsport 10-31-2008 10:19 PM

Quote:

Originally Posted by Paulporsche (Post 4274379)
Thanks, Steve.

If springs are intact, is there anything else that could cause this?

Is there any reason why someone would deliberately ramp up the advance this quickly?

Either someone put in a very aggressive advance curve, or the weights may be stuck,........:) :)

Sounds time to remove the distributor and disassemble it to clean it up and make certain that its working properly. The latter aspect should be done on a distributor machine.

mb911 11-01-2008 03:41 AM

polarity backwards on MSD? done that once or twice with the same results

Paulporsche 11-01-2008 04:35 AM

moneymanager,

LOL! Can never rule that out.

Steve,

Thanks again.


Ben,

Interesting. I thought I read somewhere that there can sometimes be issues between MSDs
and the dizzies, but I couldn't remember what they were. I'll have to check out the polarity. Thanks.

stlrj 11-01-2008 05:37 AM

[QUOTE=Paulporsche;4273744]A mechanic who was recently working on my car said I am getting full advance @ 2000 rpm. QUOTE]


As long as it does not ping, consider yourself lucky. All in at 2k will enhance low end torque and throttle response.

Paulporsche 11-01-2008 06:27 AM

stlrj,

You might be on to something. This setup was prepared by Rudy Bartling (Google him if you don't know who he is; kind of an older Grady Clay w/ a German accent!) who's been working on these cars since the late 50s. I've been using it for something like 17 years w/o problems. The MSD has been on for 3 years. My mech said he found no broken springs.

Ben,

When you say you had the same results, you mean that polarity made no difference to the advance curve?

Steve@Rennsport 11-01-2008 08:15 AM

Paul,

If the polarity of the wires that trigger the MSD unit is reversed, the advance curve is about 15degrees off. :)

This is a common occurance so its something to check.

The green coaxial distributor trigger wire should be connected as follows: center conductor to green MSD wire & violet MSD wire to the shield.

stlrj 11-01-2008 10:51 AM

Quote:

Originally Posted by Steve@Rennsport (Post 4274972)
If the polarity of the wires that trigger the MSD unit is reversed, the advance curve is about 15degrees off. :)

.

That far retarded would have been noticed by your mechanic since your engine would barely idle if it started at all.

mb911 11-01-2008 12:36 PM

Quote:

Originally Posted by Paulporsche (Post 4274818)
stlrj,

You might be on to something. This setup was prepared by Rudy Bartling (Google him if you don't know who he is; kind of an older Grady Clay w/ a German accent!) who's been working on these cars since the late 50s. I've been using it for something like 17 years w/o problems. The MSD has been on for 3 years. My mech said he found no broken springs.

Ben,

When you say you had the same results, you mean that polarity made no difference to the advance curve?


no I had way to much advance at low rpm all do to polarity


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