Check my timing ohh

[calimedeiros]

So I got my 81 targa back in March this year and today checking around and thought I would check the timing with A new timing light I bought last year
Disconnected vacuum lines and plugged them checked timing and found it was 12 degrees past my 5 tdc mark ouch
No wonder I was hearing a bit of pinging at hard runs in 3rd 4th gear
Off to the tool store I gotta get a 1/2 " wrench that has a bent end to adjust the cap
Will see how it runs when I set it to 5 tdc

[Flat6pac]

The PO might have set the timing up to compensate for the pod advance not working.
Hook a small hose up to the rear attachment on the pod and suck it to see if the distributor advances when idling.
Bruce

[Bob Kontak]

Cool you found this.

When talking timing, for all to understand, the timing is set at 5 degrees before top dead center, right? That means that the timing is advanced from (before) TDC by 5 degrees.

If it is dialed in at 5 BTDC and you plug in the retard , I think it retards to 5 degrees ATDC. This is where it fires at idle when all is hooked up.

Advance hose will do nothing until you give it some beans off idle.

That said, you are at 7 degrees ATDC doing the math without retard hose. 17 degrees ATDC with the retard hose.

The SC is wimpy as far as total advance when dialed in properly. Maybe 23 degrees if you are on the high side of the tolerance. Something like 18-23 degrees BTDC at 3,500. 5,500RPM is meaningless to check total advance timing as the SC plays out fast. Check it at 5,500 RPM though to make sure.

Based on your input, you are around 10 degrees total advance right now at full tilt.

Adjustment will wake your car up big time.

[Bob Kontak]

Originally Posted by Flat6pac

The PO might have set the timing up to compensate for the pod advance not working.
Hook a small hose up to the rear attachment on the pod and suck it to see if the distributor advances when idling.
Bruce

So the PO set the timing up to compensate for an inoperative vacuum advance but set it so it fires 12 degrees past the standard firing point?

OP - clarify what you mean by 12 degrees "past".

Is it before or after the 5 degree mark?

[Gogar]

You guys,

I think the OP means that his (lines disconnected) advance was 12 (or maybe even 17) BTDC, and he was hearing some pinging when he would hammer it.

12 BTDC would put you at 32BTDC full tilt (if I remember it right) which is too much for an SC for sure.

Unless you're on the Pikes Peak hill climb or something.

[calimedeiros]

Ok guys I had another 12 degrees more after my 5 degree mark so my idle timing was 17 degrees I dialled it back to 5 degrees at 900 rpm as per the Bentley manual plugged in my vaccum line and timing increased by 9 degrees
Checked my total timing all in at 5000 rpm it's sitting at 20 degrees
Runing good at this setting
Should be good from now on will take it for a good rip when it's not raining and check to hear if I still hear some pinging

[Bob Kontak]

Bump the bee-otch to 23 total.

Use premium gas and take it to the moon!!!! 25 BTDC (heh heh)

The wimpy total timing is because the SC is supposed to run on 87 gas effectively. Older (well, any) 911's, especially those that are performance oriented, run over 30 degrees total advance.

Premium gas explodes at a stable rate. It does not "pop" or "foof" like lower octane fuel, so it's safer. It's predictable.

[Bob Kontak]

Originally Posted by calimedeiros

Ok guys I had another 12 degrees more after my 5 degree mark

Argh - you had 12 degrees more BEFORE your five degree mark.

Before / After means something.

I am going to hang myself right after I kill my cat.

I always wanted to kill that cat anyways. Sometimes when I am in a bad mood it wants me to pet her when I get home and I am just not in the mood.

Maybe I will just deep fry some french fries and make a burger.

Goodnight all.

[Flat6pac]

There is 2 vacuum hoses. If you picked up timing at idle, you hooked up the wrong hose to the advance side. The advance pull is to the rear of the pod, the retard is to the forward side. You want retard at idle say from 5 degrees BTDC to 5 to 7 degrees ATDC. This hose is hooked up below the butterfly so there is vacuum at idle.
The other hose, advance, starts pulling at probably 3000+ to get you to to 6000 rpm and 25 to 27 degrees advance.
Bruce

[Bob Kontak]

Originally Posted by Flat6pac

If you picked up timing at idle, you hooked up the wrong hose to the advance side.

OP said he disconnected all vacuum hoses and was 12 degrees past "5 tdc"

It's in the first post. How would you interpret that otherwise?

I swear my cat is so dead.

[calimedeiros]

Yes I had 17 btdc
Is your timing not suppose to change when you hook up the vaccum lines to the pod
Mine advanced another 9 degrees
As per my previous experience on the sbc motors
Same thing happens when you reconnect the vaccum lines the timing advances another few degrees

[Flat6pac]

When you hook up the retard line at idle, you get a change to atdc or that direction
The advance vacuum doesn't kick in until you have volume air flow through the throttle body
If you're at idle 5btdc and you plug in the vacuum line and the idle advances to 17 btdc you hooked up the wrong vacuum line because that line is supposed to retard on the forward connection of the pod
Bruce

[calimedeiros]

When you hook up the retard line at idle, you get a change to atdc or that direction

The advance vacuum doesn't kick in until you have volume air flow through the throttle body

If you're at idle 5btdc and you plug in the vacuum line and the idle advances to 17 btdc you hooked up the wrong vacuum line because that line is supposed to retard on the forward connection of the pod

Bruce

So for example what is your timing at with your vaccum lines connected and at idle. ??

[psalt]

Ignition timing with both lines connected should be around TDC. The advance uses ported vacuum, (little or no vacuum at idle), originally a smooth orange hose, connected to the outside of the module. The retard uses manifold vacuum, (full vacuum at idle), originally a grey braided hose, connected to the inside nipple. It is not unusual for these hoses to be swapped or changed. The retard hose will pull back the idle timing from 5 BTDC to around TDC when connected. The advance hose should have little or no effect on the idle timing. The retard is an emission control device to meet the curb idle HC test and has the side effect of raising the engine temperature at hot idle. My experience is these cars run best with the retard hose disconnected and plugged, the idle reset to 950 rpm and the full advance checked at 25 BTDC @ 4000 rpm (no vacuum hoses).

[calimedeiros]

Oh ok so maybe I just connected my 2 vaccum hoses in the wrong ports
I'll change them around and see what happens
Do you guys think it's a problem if I leave it the way it is. ? My total timing is 20 21 degrees at 5000 rpm
But my idle timing with the vaccum connected is 14 degrees

[Flat6pac]

Idle timing with vacuum hose connected is supposed to be about 0-5 atdc
You have hoses connected wrong.
Like I originally said. Put your tongue ob the hose and the one with vacuum is retard to the distributor side of the pod
Bruce

[calimedeiros]

Ok bruce i switched the hoses yes the timing went to tdc just a touch more
Had to increase my idle screw a turn to get it to run at 900 rpm
Seems ok

[calimedeiros]

I wonder if this was causing my start up surge problem

[Bob Kontak]

Originally Posted by calimedeiros

Do you guys think it's a problem if I leave it the way it is. ? My total timing is 20 21 degrees at 5000 rpm

It's fine at 20-21. I think my 81 was spot on 21 at 3,500RPM - with no difference at 5,500 RPM ,except the noise.

You can take it to 25 and I would think you could feel a difference in grunt from 20. Suggest 89 octane though at least. Just a bit of insurance vs. 87.

[calimedeiros]

Just took it for a good rip no pinging heard at all