[steve392]

I want to set my static timing as close as possible before starting up my engine for the first time. I read a procedure to do this by using a timing light and having the ignition switch turned on (in fact, I think I read it here..).
The engine will be at TDC (firing) on #1 cylinder and distributor will be installed with rotor pointing to correct terminal on distributor cap. So far, nothing new.
For sake of discussion, lets say I want to set the timing at 10 deg. BTDC.
I'll back up the crank to 10 deg. on the timing pointer, hook up a timing light onto #1 plug wire, and turn the ignition switch to "run". Now, if i slowly turn the distributor housing, shouldn't I get spark to the plug? That way the static timing will be dead-on. Seems like it will work, or am I missing something?
If I need the secondary ignition, I do have a relay set up to provide it to the distributor with switch in "start" position only. I would just disconnect starter wire and have helper turn switch to "start" while I rotated distributor.
Like I said , seems like it will work. What do you think???

Steve

[coupster]

Yes you can static time an engine, this is the only way we time aircraft recip engines. Your timing light will not work because you wont create a spark moving the dist that slowly. We use a timing box on aircraft that is nothing more than a ohm meter hooked to a light and buzzer to tell when the points open. On elctronic ignitions I do not know how you would do it, maybe the timing light would work on those. Another note you would not want too turn the engine backwards to the 10 degree mark as there will be slop in the cam drive mechanics. Mike

[onovakind67]

I set the timing in the ballpark by setting the engine at 10°-15° BTDC on the #1 firing stroke, point the rotor directly at the #1 wire and leave the distributor loose enough to rotate. I hook up my timing light and fire the engine. The first thing I do is set the total timing to 34°, usually within 10 seconds and it's good to go.

[66GMC]

Let me start by saying that I'm a partsman, not a mechanic ... and hopefully someone else will confirm or deny what I believe to be true.

IMHO it will work on a breakerless system, because the armature and pickup coil work together to generate a pulse which triggers the coil. Points rely on a physical connection to do the same thing, but I would expect the same result within 1°? I don't think it has much to do with the speed of rotation ... perhaps in a magneto system it would?

As far as the timing chain slop goes ... if you rotate the engine back to say ... 20° BTDC, then forward to 10° BTDC you should be able to negate any of this effect.

Don

[steve392]

I should have mentioned that is an electronic breakerless HEI distributor.

Although I mentioned "backing up the crank", I'll either bring the crank around to TDC (firing) again or back up farther than 10 degrees and then rotate crank in correct direction to take up timing chain slack.
I'll probably just time it by aligning the rotor with the #1 distributor terminal and the crank at 10 deg. BTDC and set total timing where I want it once the engine fires.
It seemed like a good idea at the time.....
Steve

[Henry Highrise]

Originally Posted by steve392

I should have mentioned that is an electronic breakerless HEI distributor.

Although I mentioned "backing up the crank", I'll either bring the crank around to TDC (firing) again or back up farther than 10 degrees and then rotate crank in correct direction to take up timing chain slack.
I'll probably just time it by aligning the rotor with the #1 distributor terminal and the crank at 10 deg. BTDC and set total timing where I want it once the engine fires.
It seemed like a good idea at the time.....
Steve

Thats the way I always do it.

[docvette]

Originally Posted by coupster

Yes you can static time an engine, this is the only way we time aircraft recip engines. Your timing light will not work because you wont create a spark moving the dist that slowly. We use a timing box on aircraft that is nothing more than a ohm meter hooked to a light and buzzer to tell when the points open. On elctronic ignitions I do not know how you would do it, maybe the timing light would work on those. Another note you would not want too turn the engine backwards to the 10 degree mark as there will be slop in the cam drive mechanics. Mike

Doc here,

OK, on The Aircraft engines, you need the buzzer because the magneto needs to develop a charge to fire the points..To do that it must be rotating (more than one turn..)

On a points type ignition, yes, it will show a spark at the plug..(anyone whoever has turned the Dizzy stop to stop, with the key on, on a stopped engine, and had a Backfire Can tell you this )

The source current is DCV from the battery, To the coil..Back down to the Points , and condenser, to Buffer and shape the spark, to ground..by opening and closing the air-gap, loading the coil, and producing a spark across the gap, and at the high tension output Back to the rotor..

If you think about it, and ever pulled the coil wire on a points system, then manually opened and closed the points, a spark jumps from the center tower to the coil body OR either terminal..(or sometimes your hand or watchband )

The only difference between that, and the number 1 plug..is the cap and rotor are in place..and the manual excitation is done by the advance/retard movement of the dizzy, instead of opening and closing the points with a screwdriver.

Electronic (HEI type) Ignitions are not that much different..

Instead of the points being dependent upon a Mechanical Contact between a movable arm and a high speed cam, (and all the mechanical wear it causes) It has a Magnetic pickup and and a star that passes by it to magnetically open and close a small switch. (or in some cases an optical sensor "light/Dark")

The module is nothing more than a Buffer/Shaper, and high speed switching amp, and in some cases, with added delay time (EST modules)

In any case, it all ends up imposing an "open/Closed" Signal across the Coil primary, to generate a spark to the rotor.

So now for MY question...

WHY , on a first to life engine do you need it this accurately close? Once the engine Warms, and the Cam breaks in, The oil fills up "Dry Gaps" , The Choke opens, this will all change slightly anyway..Which is why you want to check it again after to ensure it is "All Good"..

For me, Compression, TDC, #1 Plug, Valves closed, mark at 0, has always worked well until the rest of the engine gets up to speed..(after cam break in, Fully oiled, and WARM ) and you usually need a little time setting up the tuning after anyway..It seems logical to me to just do it then..(not saying that spiking the Dizzy DEAD on "XX Degrees" when installing isn't good...just maybe a step that may be subject to change in a short while after run~in..)

So long as it is accurate enough to fire and run (Without Backfire a definite No,No, on a NEW unspun cam and chain) within a few degrees, It should be fine.

Doc

[onovakind67]

If you set the timing correctly as soon as the engine first fires, you reduce the chances of high exhaust temperatures and discolored headers.

[ElegantInventor]

I have worked on some very high performance engines that have a Low Tolerance for Mistakes where initial timing is concerned. Any misfire, backfire, or error can be extremely expensive with some engines. I watched someone try to start a newly rebuilt V12 with 5 cam chains... it only backfired once and it sheared off so many parts it never ran again.

With durable engines of moderate power, a great many mistakes can be made and recovered from. American engines? I have seen plug wire order all wrong, initial timing wrong, timed 180 degrees out, and they survived. I have witnessed a backfire that split Borla exhausts like they were soda straws. Seen flames that hit the ceiling, flames leap from carbs.

The Ferrari engine above lasted 4 seconds. What a waste.

My method for setting intial timing, when you absolutely must have it right:

1) remove all the spark plugs

2) since most performance ignition coils can be damaged if every spark doesn't jump a gap to ground, put all the sparkplugs back into the wires.

3) ground every sparkplug body shell against engine parts that are metal and grounded. I use clear vinyl hose from ACE hardware over the sparkplug threads, and use it to hold a bared copper wire to the threads. Ground the other end of these wires to engine ground.

4) insure no flammable material (like fuel) is near the sparkplugs, or better, slip a piece of vinyl hose over the exposed sparkplug tips if any doubt exists

5) leave choke open and fuel pumps and/or fuel computer off if possible. empty the float bowls if possible, or bleed fuel pressure off. Pull pump fuses.

6) setup timing light normally

7) crank engine over and set timing. If your engine isn't timed and making good sparks, fix it.

The ignition timimg is set... it will at least start and not just explode something. Put the plugs in, and connect the fuel pumps. Make sure the firing order is right and wires tight.

Timing light check at once as the engine runs. If timing is not correct, shut down to protect header finish. Let it cool, try it again.

Jon P

[steve392]

Thanks again for everyone's replies. This was not something that I needed to do for accuracy when I first start up, more of a theoretical question, thats all....

Steve