Timing Mallory Unilite mechanical Advance

[Chris Nelson]

I have a timing light, but I am not experienced in its use. Can someone give me step by step the setting of the timing? The engine is an 8BA with a 77B Isky cam, dual 97s and a PCV valve and Mallory mech. advance dist.
The car starts hard and stumbles when cold, but fires up easily when warm and runs smooth. I'm not sure of the timing at present.
Chris Nelson 206-915-4773

[tubman]

In my opinion, the factory timing specifications go out the window when an engine is modified to any extent, especially if the camshaft is changed. What I have done with modified engines is to disconnect and plug the vacuum advance (if any), and hook up a vacuum gauge. I adjust the timing until the vacuum gauge shows the highest reading, and then retard the timing just a smidge. This has worked for me on everything from flatheads to Chrysler hemis , to even (gasp!) SBC's.

All of this aside, the symptoms the engine is exhibiting don't look like an initial timing problem to me.

[rotorwrench]

Timing does change some with modifications but the initial timing and full advance are still lower than the average OHV engine. When mechanical advance is all you have then you have to know what rpm is starts to advance in order to get the initial timing at idle rpm. If it doesn't advance at all at idle, then you can set the minimum there without locking the advance in position. Initial on a stock 8BA is 2 degrees by the single mark on the pulley aligned with the pointer. Stock may not apply for your engine. Idle RPM will generally be different with a cam. Your engine timing will depend on the cam specs and what your distributor advance curve is set to.

All engines have to warm up some before they run to normal operational settings. Modern fuel injection systems have cold start built in to their design but carbs just have a choke with manual settings. If the engine runs well after warmed up then you are already somewhere in the ball park but you may need to have your advance curve set up on a machine before you go much further. Whom ever does the check needs to know flatheads.

[flatjack9]

I would set initial advance at around 4 deg BTDC. Your problem sounds more like carb than ignition.

[19Fordy]

I agree with tubman. The vacuum gauge is your friend.

[Ol' Ron]

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The above information is good stuff. What's important is to find out what in the distributor. You can do this by placing a mark on the crank pulley about an inch away from the dot. this is around 20 degs. Now with a warmed up engine and the timing on the dot. rev the engine and watch the pointer. It should come up to the mark you put in the pulley and stop. If it goes much further than the mark, you might have too much. If it doesn't come up to the mark, not enough. This is a backyard distributor machine, but you might have to putz around it some.

[Paul Bennett]

Originally Posted by Chris Nelson

I have a timing light, but I am not experienced in its use. Can someone give me step by step the setting of the timing? The engine is an 8BA with a 77B Isky cam, dual 97s and a PCV valve and Mallory mech. advance dist.
The car starts hard and stumbles when cold, but fires up easily when warm and runs smooth. I'm not sure of the timing at present.
Chris Nelson 206-915-4773

1. Engine off, jog gently so the engine damper, with the timing mark bump, is visible. Clean dirt,grease etc from the bump and the pointer. Mark the timing bump and the pointer with white paint. Use hobby thumb sized bottle or white with brush in cap or even use white rattle can paint on cardboard and a long handled brush to mark the timing mark bump. Some even paint the area black before using the white but this depends upon your eyesight and ability to see the marks.

2. Connect the timing light to 12v (use motorcycle battery if your car is 6v). Fiddle with the timing light until you are comfortable getting the output lens close to the damper to see the bump without endangering contact of your hand or the timing gun with the fan.

3. Before the adjustment phase, park your car in a position (garage or tree) to minimize the ambient light. You need to easily see the timing mark.

4. Barely loosen the bolt which holds the distributor just loose enough so you can turn it with some resistance.

5. Vacuum gauges are inexpensive, this would be a good time to connect it.
Now you are ready to set the timing using suggestions above. Hope this helps. O'Ron suggests an additional 20° mark but needs to say which direction on the pulley to place it - O'Ron

GL

[tubman]

Hell, I'd put two marks on (one on either side) just to be safe. At my age, it's easier than trying to remember which way to go!