911SC distributor question - pleas dont move

[ramonesfreak]

yea I know this isnt the tech section but I know there are a lot of SC owners here and this section seems to be more active...I have spent so many hours looking for this simple answer that im going crazy

Can someone please tell me which vacuum hose NIPPLE off the distributor is the retard and which is advance?

I want to confirm that my hoses have not been on backwards for the almost 20 years i have had the car

the hose (below) on the right (red) has strong vacuum when I increase RPM ---I would assume thats advance....is it on the right nipple?

The hose on the left (blue) has good vacuum at idle....is it on the right nipple?

[ramonesfreak]

Post #2 here suggests to me that these hoses are on backwards

SC distributor vacuum question

As does this

'82 911SC Distributor Vacuum Line Connection Question

[ramonesfreak]

And this guy just answered my question so

this can be deleted unless anyone wants to tell me something

1983 ignition timing vacuum hose question

[Scott Douglas]

Sorry, nothing to add.

[Superman]

It seems to me that reversing those hoses would have a strong negative effect on performance. We'd like to hear how this engine runs once everything has been re-sorted.

[ramonesfreak]

I can tell you. --- just tried and I have a new issue

i posted this to my tech forum thread

Something aint right

I switched them around and immediately the idle was way too high

Brought the ide down to 950 and drove about 3 miles. Tach need doesnt come back down. Stops at about 1,500. pulled over and readjusted idle to 950 and drive again. Now needle drops to 0 and car stalls in intersection :-)

my intermittent slight power loss at 2000 RPM is gone (which is what prompted me to start learning about distributor because car always seemed perfect until this spring) though but something is not right now

__________________

[ramonesfreak]

on a good note, the car does run different/better. I only drove it around the neighborhood city streets but definitely noticed it gets up to speed quicker and seems to be moving faster for any given RPM compared to how it was.....

Its not a huge difference but I can tell that it is now improved

[908/930]

Pull the dist cap off and make sure your advance mechanism moves smoothly, any play on the shaft? Does your car have any valves inline with the vac lines from the dist?

[billybek]

There is a little pad under the rotor for lubricant for the advance mechanism. I remember my cap was brutally hard to get the clips off for some reason.

[ramonesfreak]

Originally Posted by 908/930

Pull the dist cap off and make sure your advance mechanism moves smoothly, any play on the shaft? Does your car have any valves inline with the vac lines from the dist?

No not that I’m aware of.

The idle issue seems to have calmed down and I’ll set timing in a day or two and see what happens

[john70t]

I wouldn't drive it until the vacuum hoses are correct and specs are known.
The 3.0l is an excellent engine but.

Grady Clay aka Early S man (?) with his extensive knowledge of tech literature contributions doesn't seem to appear on the Pelican Search...


My rusty knowledge of CIS is limited and the following could be entirely wrong:
-One hose is definitely a timing advance hose tied to RPM. More speed equals more vac to turn the points plate.

-Vacuum retard balance of the advance mechanism (due to load at any rpm) should come from the intake manifold I would guess. Highest manifold vac is at idle. 18-24 IIRC for a good running engine. I haven't wrenched in a while

-There is divot hole in the throttle plate to allow some air through. There is a manual air bypass screw which must be set correctly. 1.5-2 turns out from seat or something. I don't remember at all. There is a large air hose bypass controlled by solenoid tied to the computer.

-Fuel injector seals and especially the CIS boot have to be changed occasionally to prevent air leaks. There is a VW/Porsche tool for the first. Be careful with this and don't break anything using leverage. They will be like rocks after decades in a hot engine.

-There is the Warm Up Regulator which puts pressure on the the fuel plunger in the CIS system. I think that is heat sensor/electric but could be wrong.


Lubricate everything possible, a dab of marvelous mystery oil in the gas, and start from from scratch would be my WAG.

[ramonesfreak]

I have it hooked up right now.

You wouldn’t drive it until it was right? Well, I drove it almost 20 years and 35k miles with it backwards and had no idea so……even if still wrong, probably wouldn’t matter if I drove it one more day

But I’m good now

[908/930]

One other thing to consider, there is also mechanical advance built into the dist assembly, likely should be cleaned and lubed about every 10 years.

That drop in idle speed could also be caused by your auxiliary air regulator acting up.

[pmax]

[id10t]

OK, this probably doesn't apply and I'm a mechanical idiot and don't know anything about 911 dizzys...

But when I had similar problems in my 356 I discovered that dad's prior mechanic used a VW 009 distributer intstead of one with the proper advance curve for the 356C engine (a VW 050 is fine, meant for the alcohol powered bugs).

So... I have to ask.... do you have the right distributer in there? With correct points/condensers/etc ?

[1990C4S]

Wouldn't you normally confirm the advance by revving the engine while you used a timing light?

[ramonesfreak]

Yea I have the original distributor

And yes you confirm advance is working with timing light

But can confirm vacuum is ok at the hoses by unplugging and using a finger at the hose opening.

As stated above, I confirmed mine were installed backwards by the prior owner

https://forums.pelicanparts.com/porsche-911-technical-forum/1144485-1983-ignition-timing-vacuum-hose-question-2.html#post12064425

I’m all set now. Just need to check my timing this weekend and put this behind me.

Unfortunately I’ve experienced almost 20 years with my 911 not accelerating as optimally as it should. I’ve never driven another air cooled 911 so I had no point of reference and there was no obvious issue. I only discovered the hoses were backwards when I started diagnosing a power loss under light load at 2k RPM. Power loss is gone now. I believe a combination of the distributor mechanical advance needing lubrication and not having the vacuum advance properly connected to assist with low load advance was causing my power loss at 2k RPM. If that power loss had not happened, I would still not realize the hoses were backwards and I would be ignorantly believing my 911 performance was normal.

A good learning experience and if you have a late SC with 2 vacuum hoses at the distributor, it is best to check they are connected properly

[Bob Kontak]

Originally Posted by john70t

Grady Clay aka Early S man (?)

Two different people.

Early S Man died a couple years before Grady.

[john70t]

Major faux pas there. Shameful of me. They were true legends outside the tech forums as well.
They should be go-to stickys.

(Cat missing. Email inaccessible. Computer acting funky. Got frustrated. Made the mistake of shvodkas. That's no good at all.)

FWIW a MityVac hand pump comes in handy for manually checking vacuum operations.

[speeder]

Find a good shop that knows air-cooled 911s, you're not qualified to be working on your car. I don't say this to insult you, people's talents lie in many different areas. Yours do not lie in mechanical things.

Wayne started this website in order to encourage everyone to work on their own Porsches so that he could sell more parts directly to customers but the results have been untold numbers of butchered and ruined cars in the 20+ years I've been here. Determining which diaphragm in a vacuum unit move the distributor in which direction is about as complicated as a steak knife. You simply remove the distributor cap and apply vacuum to each nipple and see which way it moves the plate in relation to the direction that the rotor turns. If any of the last sentence confuses you, move away from the car and take it somewhere. Driving around with vacuum advance/retard hoses on backwards could have a very negative effect on timing and cause overheating, among other things. Ignition timing on any engine is important, on an air-cooled engine, it can be life or death.