Timing marks on my 911

[steve meltzer]

I've set the timing on a number of cars in the past and have a nice "dial back" timing light. The car is '69E with a '73T MFI motor. There are two timing marks on the balancer; they are probably 5° apart, but have NO other marks on them. No letters, or insignia. I have no hx on the car and not sure where the balancer came from, which of the two marks is TDC, nor what the second mark indicates. Short of a piston stop, how do I determine which mark is TDC? Will a piston stop differentiate a 5° delta?

All of the engines that i've been involved with had an initial timing that was BTDC, but according to my source this motor should have a base timing of 5° ATDC. Once i know which mark is TDC, how do I use the light to find 5° ATDC? Doesn't the light only advance and retard between TDC and a BTDC value? Once I've found TDC, shouldn't the 5° ATDC mark reside to the left (CCW) of it?

Finally, if the left-most mark is 5° ATDC, wouldn't i just line it up with the case w/my my light set to "0"?

Am i over thinking this? thanx steve

[Showdown]

Try taking a little mirror behind the pulley toward the front of the car and you might find the stamps for TDC, 5 deg… etc. that was my experience.

[steve meltzer]

Thanx "Showdown". I'll check and post after Thanxgiving. s

[Bill Verburg]

Originally Posted by steve meltzer

I've set the timing on a number of cars in the past and have a nice "dial back" timing light. The car is '69E with a '73T MFI motor. There are two timing marks on the balancer; they are probably 5° apart, but have NO other marks on them. No letters, or insignia. I have no hx on the car and not sure where the balancer came from, which of the two marks is TDC, nor what the second mark indicates. Short of a piston stop, how do I determine which mark is TDC? Will a piston stop differentiate a 5° delta?

All of the engines that i've been involved with had an initial timing that was BTDC, but according to my source this motor should have a base timing of 5° ATDC. Once i know which mark is TDC, how do I use the light to find 5° ATDC? Doesn't the light only advance and retard between TDC and a BTDC value? Once I've found TDC, shouldn't the 5° ATDC mark reside to the left (CCW) of it?

Finally, if the left-most mark is 5° ATDC, wouldn't i just line it up with the case w/my my light set to "0"?

Am i over thinking this? thanx steve

[ryanpope]

Originally Posted by Bill Verburg

what about a 1983 -911 SC?

[Walter_Middie]

what about a 1983 -911 SC?

I have made one of these "cartoons" for most years.

if the left-most mark is 5° ATDC, wouldn't i just line it up with the case w/my my light set to "0"?

Steve - yes, if you keep the timing light at "0", you would line up the 5 deg mark (the mark to the left of the TDC mark) at idle with the stationary pointer. When you rev the engine, the marks will move. An easy way to see when you get to 38 deg is to set your timing light to 38. Then when you rev the engine and the timing moves to 38 deg, what you will see is that the TDC mark will line up with the stationary pointer. If you dial the timing light back to "0", then the pulley will show the 38 deg mark (if you have one) line up with the stationary pointer.

[HarryD]

Hi Steve. These are the timing marks on my 1973.5 911T.