Okay, last week I replaced my timing chain and gear and rotary button. And Now I've been trying for a week to time the freaking thing. THe rotary button has three timing points? Which one do I point to the #1 piston on the comp stroke??? Ive never seen anything like it. I've had four mechanics look at it and they cant get it timed either. Now we are all stumped and would really like to know how to time it. It has a Variable Venturi Carb if that makes any difference. I almost had it once I thought but it acted like it was still slow, but when I advanced it, it only got worse. What is the correct way to time this motor??? I would really appreciate any advice or help you guys could give me, Im very stumped here. Thanx guys.

 

I've never heard of a rotary button.

If you have an EEC controlled (TFI-IV) ignition you are supposed to disconnect the single wire SPOUT connector otherwise you won't get an accurate timing measurement.

 

Does your distributor rotor look like the one in the photo below on the left? That's EEC III. You can confirm that if there is no vacuum advance diaphram on the distributor and the ignition module has a brown colored grommet. With this type of distributor you cannot adjust the timing. The distributor advance is controlled by the ECM. The only thing you can do is align the distributor shaft and adaptor so it has the correct reference when the ECM advances or retards it.

Post back to confirm and I can give you the procedure for distributor alignment.

Scott

 

THats it exactly!!!! Please show me how to make this truck run again!!!!

 

Okay. But first one other thing and this may be the main reason your truck won't run.

This distributor has the normal 351 firing order, 1-3-7-2-6-5-4-8 but is has a different wiring order. So the wires still go counter clockwise from #1, but the order is 1-5-7-8-6-3-4-2. This is because this is a 180 degree distributor.

The way this distributor works is by firing alternately 180 deg from both sides of the rotor. So #1 fires, turn one to the left and 180 deg and #3 fires on the other side of the cap. Turn one to the left and 180 deg and #7 fires and so on.

That's why there are electrodes on both sides of the rotor.

The other thing you need to do is coat the electrode blades on the distributor rotor with silicone grease. You do not grease the two high voltage pickups that stand up vertically. Also grease the electrodes in the cap shown at the locations I've circled in the photo in the post above. I believe this is to prevent arcing, and the grease needs to be applied about 1/32" thick.


Okay, now the distributor alignment:

With the rotor removed, rotate the crank to align the smaller notch in the dist. shaft with the notch in the adaptor. With cyl #1 on compression stroke, the timing mark on the vibration damper should be plus or minus 4 degrees of TDC when the two notches are aligned.

So, with the notches aligned if you are within 4 deg of TDC, you're good and it's close enough.


If you are off by more than 4 degrees:

The procedure then is to turn the engine so the timing mark is at TDC and then loosen the two bolts holding the sleeve assembly on the distributor shaft. Then you can put a screwdriver in the notch in the shaft and turn it so the smaller notch in the shaft aligns with the notch in the adapter. Once aligned, tighten down the two small bolts on the sleeve assembly. You are supposed to use a special alignment tool that fits in both notches and holds them true. Eyeballing it works just fine as long as you don't disturb the alignment while tightening the two sleeve bolts.

Here's a photo showing the notches in the shaft and adaptor aligned. The two small bolts securing the sleeve can be seen on either side of the shaft.

Scott