Question about timing marks, smog shop failed me 79 911SC
 

i have a late build 79 911SC.

The timing on the lid says that the car needs to be at 5 BTDC. The smog shop failed the car because they said it was 7ATDC.

Would not disconnecting the vac lines cause that much advance? I am thinking they didnt disconnect the lines when checking.

The car was just tuned up at a reputable shop, i check the notes and it says timing was set. Car idles right around 900.

thanks!

I would go back to the shop and ask them. Where are you located?

You're getting confused. The vacuum line to the single port pod is for advance at high RPMs. Remove hose and plug
Set your 5 degrees BTDC @900 then plug hose. There should be no decernable vacuum at idle in the hose.
Now, make sure the upward fingers inside the distributor have some circular movement available.
If the fingers are frozen that's another problem that might be related.
Bruce

Sorry a tad confused with your statement. there are 2 vac lines on the distributor, which one are you refering to?
http://forums.pelicanparts.com/uploa...1401549032.jpg

you say to remove hose and plug, then set timing, and to plug hose again?

i found this picture, where the timing mark lands currently with the gun with vac connected @900 is to the left of the z1 mark.

http://forums.pelicanparts.com/uploa...1313957490.jpg

Ignition distributor.......
 

Infinkc,

Inspect and check the Bosch ID number on your ignition distributor. It looks like a different part for your '79 SC. Cross reference the part number using the CIS Primer by Jim Williams or other shop manuals. Keep us posted.

Tony

sorry the picture i used was from searching the web, not the actual. I just wanted to show it had 2 vac lines.

Bosch part number.......
 

And that's the reason I suggested to check the Bosch identification number of the ignition distributor. The basic question you have to establish is that do you have the correct part/s installed on your engine? If the answer is YES, you could proceed. But if the answer is NO, you know what to do next. Keep us posted.

Tony

Sounds like you car was tuned right. You failed because you are more than 2 degrees off the listed spec on the emission decal.

Do you have the correct emission decal (year) for your car? Going from my VW experience with the dual vacuum distributors, I seem to remember the ATDC specs on the labels. But maybe not.

Do you know if the smog tech referred to his emissions manual for any further instructions? These manuals are required for a smog shop to have and are used to confirm procedures and smog equipment when emission decals are missing or illegible.

The manual may have the instructions to disconnect the retard vacuum hose putting the timing back to an advanced position or 5 degrees BTDC. But Since you have a label, he went by that and maybe some of the timing instructions were illegible.

I have the manual that I can look at later today and I will look up your car.

For a 79 SC you either have the wrong distributor or the wrong pod as a 78/79 has a single hose pod. The 80 to 83 has the dual hoses.
I imagine, even wrong you can still set it up
Disconnect and plug your hoses
Set the spec 5 BTDC @900.
Connect the advance hose leave blue hose plugged
With the dual pod you're testing as a 80 to 83 with ox sensor and the engines are supposed to pull 7 degrees ATDC. 78/79 aren't supposed to pull it back.
Bruce

ok, this is where i have been confused with this car, since it is a late 79 build, but its registered as an 80. Is there a cut off point where i can say this is an 80? I just had to replace the gas cap also because it failed smog also, it has the all metal cap which pelican parts has listed for a 79, 80 went to a red top.

The engine does have the dual pod and is at 7deg ATDC like you say, but the trunk sticker has 5BTDC.

As far as i know everything is original to this car, i have all the service records for it and didnt ever see the distributor being replaced. The crank pulley has the marks for the 5BTDC on it.

What pictures should i take?

Ok, just to put an update to this thread.

I got the procedure from the factory manual to properly adjust/check the timing. It explains that you need to check with both vac lines disconnected, and adjust the idle to 900rpm, then check timing. I checked it and it was spot on. spec is 5btdc on my 80 with the dual pod distributor.

To the car back to the smog shop, complained, they re-checked per the manual and also their computer instructions and its passed fine. The tech before that did the test did not do it correct they admitted.

Late '79 might be a MY80 car. My Euro 1980 SC came out of the factory in August 1979 according to the original German registration. My VIN is 91A013xxxx (for US, 91A014xxxx) and a '79 would be 91193xxxx (for US, 91192xxxx.) Where does yours fit?

I like a happy ending! :D

its a US, 91A014xxxx, so by what you say its an 80. Thanks!