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Old 01-03-2019, 02:43 PM   #3
jcwren
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Join Date: Nov 2018
Location: Flowery Branch, GA
Posts: 207
Re: Correct distributor insertion for 250 L6?

Quote:
Originally Posted by RichardJ View Post
>> TDC on the compression stroke. I'm using the timing mark on the pulley and the timing mark <<

This is a 4-cycle engine that turns two complete revolutions of the crankshaft or 720 degrees of rotation for each cylinder firing event. For each firing event the TDC mark lines up twice, but fires every other revolution.
The plug must fire at TDC Compression Stroke, but not on the TDC Exhaust Stroke.

If you don't understand that or can't determine TDC Compression, then stop.
This much I do know

Quote:
On your #3 ............. 1/8 turn more toward left cylinder bank and ...............
An inline engine doesn't have a left bank, so I'm not sure what you are reading.
Reading straight from the service manual, "ST_133-70 Chevrolet Truck Chassis Service Manual Serial 10-60", page 6Y-31, "Installation -- Engine Disturbed (All Models)", step #3. It covers both the V8 and L6, sometimes in the same paragraph. For the L6, I took this to mean the ONLY cylinder bank.

Quote:
I've seen that picture with the green circles before. The guy that originally posted that picture did not understand what he was doing. He seemed to think the rotor needed to be pointed to the spark plug in the #1 cylinder.
You correctly understand that the rotor points to the #1 wire tower on the cap.

#4 is all about getting the distributor to drop down onto the oil pump slot and still keeping the rotor pointed the way you want it to. On a six, it is very easy to reach down to the pump with a screw driver and light.
Agreed. Their suggestion is to bump the engine, I've just been turning the engine by hand (plugs are loose) until it drops down. The distributor gear is engaged even though the oil pump is not.

Quote:
Static timing with points distributor.
1. Move the crank timing mark to about 6 degrees BTDC. ( On the compression stroke)
2. Rotor pointing to #1 plug wire on cap.
3. Remove #1 plug wire from #1 spark plug and attach any old spark plug to it. Place the plug on any unpainted surface on the engine so the plug body is grounded.
4. Turn ignition key to "ON".
5. Rotate distributor body back-and-forth until you see the old plug fire. Do this as many times as needed to feel comfortable that you have found the correct spot when the plug fires.
6, Reconnect the plug wire to the #1 plug and start engine. If you were careful, your timing light will show that you are within 2 degrees.
The plug should fire just as the points open. I've seen the suggestion of using a ohmmeter to determine when the points open. Any reason to avoid that method?

Good stuff, thanks!
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