Timing marks kinda weird

[mark houghton]

Embarrassed to to even ask, but this has been bugging me since I took ownership. My crank pully doesn't have the traditional Z1 stamped on it, and only two main timing marks. I marked them both some time ago...one with a drop of white and the other red...they've gotta be at least 20° apart. See the picture.
With my dizzy rotor pointing to the TDC notch, the pulley lines up with the white notch. If I recall, with the engine running, I've set the timing about midpoint between the two, shooting for around 10° advanced, and the car runs fine. Also note that my dizzy is cranked close to the end of its adjustment, advanced in other words. If I were to reset (retard it) to more of a midpoint and then line up the rotor to the TDC notch, the pulley timing mark would correspond to the red notch.
Sooooo...the red mark that's left of the white mark is most likely TDC, and the white mark is for timing at 4000 rpms.
Agreed...? And yeah my rotor looks crappy.

[Alan L]

So you need to find which is actually TDC. The rotor thing is just a general indicator - like which bit of the rotor?
You have a couple of options. Since you are doing a valve adjustment - you could look at the Inlet valve depression on #1. That will give you a definitive answer. When you are approaching your 'Z1' marks keep an eye on the valve clearance. This is when your rotor is on or approaching the dizzy mark. So now you know you are approaching TDC on #1. The valve will start to depress. Once it has moved a mm or so, which mark is within spitting distance of the case line?
Then you have the answer.
But you knew all that I am sure.
FWIW I think my pulley is same - no designated Z1, and I think 3 marks - two close together and one for full advance.
Alan

[mark houghton]

Originally Posted by Alan L

So you need to find which is actually TDC. The rotor thing is just a general indicator - like which bit of the rotor?
You have a couple of options. Since you are doing a valve adjustment - you could look at the Inlet valve depression on #1. That will give you a definitive answer. When you are approaching your 'Z1' marks keep an eye on the valve clearance. This is when your rotor is on or approaching the dizzy mark. So now you know you are approaching TDC on #1. The valve will start to depress. Once it has moved a mm or so, which mark is within spitting distance of the case line?
Then you have the answer.
But you knew all that I am sure.
FWIW I think my pulley is same - no designated Z1, and I think 3 marks - two close together and one for full advance.
Alan

Yeah, which bit of the rotor...I'm with you there! Since I don't have a marked Z1 and the second notch 5° after it, I'm presuming that the notch I marked red is TDC, primarily because the only other mark is probably close to 30° advanced from there for the 4000 rpm full advance timing.
I'll rotate the crank and watch the valves. I've done weirder Fred Flintstone things on past vehicles...run a wood dowell down the bore through the spark plug hole to gauge when the piston is at TDC. Supremely accurate, that!
Thanks for chiming in.

[Alan L]

Yeah - well that was option 2. And it would work well enough. If your pulley is same diameter as mine, remarkably (?) the circumerence distance is the asme as degrees. So if you get a piece of tape and mark the two marks on it - while stretched around the pulley, that will give you the degrees between the two marks. So the pulley circumference is 360mm. So your piece of dowel wood would be able to tell, at least within 5 deg where TDC is. Which again would show you the TDC mark.
Alan

[Alan L]

If you use the valve method, with the rotor near your dizzy mark, (so you are on the right stroke) you will get a valve movement about 5 deg (5mm) before Z1.
Alan

[Alan L]

You would think the first mark to hit the case line is your BTDC mark - advanced timing.
The 2nd mark should be your Z1. It may be your timing specs at idle are 0 deg.
Alan
Edit - my pulley is same as yours - 2 marks - about 25-30mm apart.
And my idle timing spec is 0 deg.

[gorskined]

mark
i noticed your distributor looks to be at the end of the adjustment.
mine sits about 1/3 the adjustment away from the opposite end also my #1 plug sits much closer to where your #5 resides, but mine is a 76 row .
. When i put my motor back together i originally put the distributor in one tooth over like yours and i couldn't access the rear clip to snap it in place . so i lifted the distributor and rotated one tooth over. is your timing 100 percent correct ?
im only asking because ( new to the turbo world originally a 356 guy ) i was wondering if i was able to clip the distributor cap would i have been able to time the car one tooth over ?
also asking because my car is a 3.0 row and im using the 3.0 American distributor. The row motor has a different timing but the setting reflect the same degrees offset for advance and retard. i believe the American timing is +5 at idle and -25 at 4000 and the row is 0 at idle and -30 at 4000 so basically its the same distributor just timed differently. both have a 30deg curve .. i have both distributors the row and the American and i couldn't find any difference between the two, other than the part # ... i used the American distributor because it was in the car when i got it and looked to be in much better shape Than the row distributor that was in a box on the back seat.


Thanks Regards Ned

[mark houghton]

Originally Posted by gorskined

mark
i noticed your distributor looks to be at the end of the adjustment.
mine sits about 1/3 the adjustment away from the opposite end also my #1 plug sits much closer to where your #5 resides, but mine is a 76 row .
. When i put my motor back together i originally put the distributor in one tooth over like yours and i couldn't access the rear clip to snap it in place . so i lifted the distributor and rotated one tooth over. is your timing 100 percent correct ?
im only asking because ( new to the turbo world originally a 356 guy ) i was wondering if i was able to clip the distributor cap would i have been able to time the car one tooth over ?
also asking because my car is a 3.0 row and im using the 3.0 American distributor. The row motor has a different timing but the setting reflect the same degrees offset for advance and retard. i believe the American timing is +5 at idle and -25 at 4000 and the row is 0 at idle and -30 at 4000 so basically its the same distributor just timed differently. both have a 30deg curve .. i have both distributors the row and the American and i couldn't find any difference between the two, other than the part # ... i used the American distributor because it was in the car when i got it and looked to be in much better shape Than the row distributor that was in a box on the back seat.


Thanks Regards Ned

Oh Ned, here we go! Tons of discussion on this forum from other much more knowledgeable people than I, and I've forgotten more than I once knew.

My shop manual covers all from 1978 on, in three categories: USA, Europe, and California/Japan...and all are different. I use the CA/Jap specs for idle @5° ATDC with hoses connected and 26° BTDC @ 4000 rpm hoses disconnected. Once you step on the gas and open the throttle body, you lose the vacuum signal and your timing advances to around 10°.

If I'm not mistaken, the excessive idle ATDC timing had everything to do with heating up the emissions catalytic converter. Some of the earlier European years ran from 0-4° BTDC and were probably not cat equipped.

Looking at all the various timing curves at 4000 rpms, total centrifugal advance is around 16° and vacuum advance adds the remaining...totalling 26° advance.

Disclaimer: quote me not, I could be way off base. Although my spec calls for 5° ATDC, I typically time mine to around 5-8° BTDC at idle with hoses connected...that extra advance helps performance.

I haven't answered your question. I suspect my dizzy had been installed one tooth off and why I'm almost to the end of adjustment. Re-indexing one tooth the other direction may put it more centered but I'm chicken to mess with it. Right now my largest concern is getting that damn rear clamp connected back up!

[mark houghton]

Specs from one source

[Alan L]

Originally Posted by Alan L

If you use the valve method, with the rotor near your dizzy mark, (so you are on the right stroke) you will get a valve movement about 5 deg (5mm) before Z1.
Alan

A slight correction - sleeping on it, on the valve timing process for Z1, your rotor will be 180 deg off the dizzy mark. You are on the inlet stroke, not firing/compression. But your pulley does 2 revs per engine cycle.
For that rear dizzy clip I use a curved piece of flat steel - to reach behind and flick it back up - til I can get my fingers to the top of the clip.
My dizzy has about 15mm spare slot on the timing adjustment - the gap of visible slot is about 5mm.
Alan

[mark houghton]

Originally Posted by Alan L

A slight correction - sleeping on it, on the valve timing process for Z1, your rotor will be 180 deg off the dizzy mark. You are on the inlet stroke, not firing/compression. But your pulley does 2 revs per engine cycle.
For that rear dizzy clip I use a curved piece of flat steel - to reach behind and flick it back up - til I can get my fingers to the top of the clip.
My dizzy has about 15mm spare slot on the timing adjustment - the gap of visible slot is about 5mm.
Alan

I've got about the same amount of slot remaining, thereabouts. Thanks. Have settled on TDC being my red mark, which when measured is 26mm after my white mark, i.e., 26°...white mark being 4000 rpm advance. Worked fine for adjusting the vavles after checking it all out this morning. Now all I need to do is engrave a Z1 on the pulley so I don't forget as my mind ages.
And as for the dizzy rear clamp from hell, I've seen your resolution and have just now done the same with a stiff piece of wire.

[Alan L]

My pulley doesn't have Z1 on it either. But the logic will tell you that the first mark to hit the case line has to be your advanced BTDC timing mark? That only leaves one mark.
You already know, but advancing your idle timing will give you better off-boost performance, but also advances your max timing same amount.
Alan

[mark houghton]

Originally Posted by Alan L

You already know, but advancing your idle timing will give you better off-boost performance, but also advances your max timing same amount.
Alan

Way back when, with my first 930, as you know I did all sorts of stuff...one of which was to install an MSD ignition with boost retard function. Memory fades, but I think I was running almost 10° advance at idle and shaving all of that off at max boost. I think these cars can handle a bit more advance than spec as long as we don't get carried away and run high octane gas.
My current machine, the only mod I've done is replacing the stock IC with the larger B&B I salvaged from my first. Took a bit of elbow grease to clean off all the fire baked patina. Been toying with resurrecting my equally baked 7006 turbo, but need to send it in for a rebuild first.
Seems I'm getting in the mood once again! Always appreciate your input Alan.