Static timing 101 Q.
 

Ok, so I'm beginning to doubt myself after spending a day in the garage and am getting tired:eek:.

To set the static timing, Z1 indicates either TDC for cyls 1 OR 4. I check to see which one it is by inserting something down into the cyl with the plug out to see when the cyl reaches TDC.

So say I feel #1 cyl reach TDC by this method, the pulley is at Z1, then I align the distributor rotor so it points to #1 cyl (or thereabouts; a bit before?)

Question: How do I know # 1 is actually on the compression stroke without removing the rocker covers? Feel free to flame if you like.

I only get one or two chances churning it over to see before my MFI floods everything or the marginal batteries go flat, so it's proving a bit testing! Haven't done this for 10 years or so and am a bit rusty. Thanks.

method 1: look at the distributor to see which wire the rotor is pointing to, 1 or 4?
Method 2: remove the top valve cover (fewer bolts, no oil leaks), grab the rocker on 1, rock it back and forth, if it moves at all, then that is the cylinder at top dead center.
Method 3: do a leakdown test on that cylinder, if it does not hold air, then the valves are open and it is NOT at top dead center. If it holds air, then it is TDC compression

I would go for removal of the top valve cover (just one is needed)

A 2-piece compression tester will make this task easier and faster w/o removing any valve covers and wiggling rocker arms.

Thread the compression tester hose into the spark plug opening. While rotating the engine, seal the open end of the hose with a thumb. If no. 1 is on it's compression stroke, you should feel air pressure against your thumb. Observe the Z1 mark as it approaches TDC. Stop about 1/4 turn from aligning with TDC (ignition timing is usually Before Top Dead Center (BTDC). If you feel no pressure, the cylinder is on the exhaust stroke, then simply rotate 360º to bring the cylinder to the compression stroke. A simple hose might accomplish the same task albeit with a weaker pressure signal due to a lack of compression seal with the makeshift "pressure" tube.

Using a wrench on the crank pulley, continue to rotate the crank to align the appropriate timing mark with the split in the crankcase. At this point,no. 1 cylinder is in a static position, ready to fire. The rotor should also be pointing to no. 1 spark plug wire on the dist. cap. If not, remove the distributor, then reinstall it so it does. Be aware the dist. shaft gear is a helical shape (not straight cut), so the rotor rotates slightly as it fully engages the drive gear on the intermediate shaft. Okay so far?

Accuracy here depends whether you want the timing to be dead nuts ON or just close enough to start the engine, then finish with a timing light or equivalent.

Remove the ignition coil wire from the center of the dist. cap and position it close to a metal ground (about 1/4" air gap).

Loosen the dist. housing holddown clamp, then rotate the dist. housing clockwise about 15 degrees.

Ignition ON (engine OFF)

Slowly rotate the dist. housing in a counterclockwise direction (note: Opposite regular rotor direction). When the spark jumps the coil wire gap you created, stop rotating the housing and tighten the clamp. Repeat this as necessary to verify the spark occurs at the same position.

To confirm the static timing is correct, rotate the engine (normal clockwise direction) with the wrench 1 or 2 revolutions (it doesn't matter) or simply push the car forward slowly in gear (5th and not downhill), then watch/listen for the spark to jump to ground as the timing mark lines up.

Note: Since you're merely looking for a spark to occur according to the timing mark, it doesn't matter whether no. 1 or no. 4 cylinder fires. They happen to normally fire 360º apart from each other (crank) and 180º apart from each other (distributor) and share the same timing mark.

BTW, if you have a timing light, when connected to the connected coil wire (inductive clamp-type), the light itself will indicate when each spark occurs for each cylinder. When connected to one of the spark plug wires, the light will indicate when the spark occurs for only that cylinder. OTOH, if you had a timing light, you probably wouldn't need this advice.

Hope this helps,
Sherwood

many thanks for the replies guys, will do another session in the garage this afternoon and see how it works. Sherwood, I do have a timing light, dwell meter, compression tester and all the bells & whistles. It's just the basics that had stumped me for not having had to do it for so long!

I've been at an Early 911NZ meet this morning (our 1 year old new club here for pre 73's) which was great, but sadly had to go in a friends car rather than take mine. Serves me right for doing a quick tune up before the event!