Dizzy issue
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Dizzy issue
The gear on the distributor (390 motor) shouldn't be able to be held still while spinning the rotor on the other end should it? Or am I misinformed about some sort of black magic that happens in these things? I went to go put the distributor back in and it just didn't feel right so I took it out and found this issue.
Laughing Gas
Joined: Sep 2003
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From: Corbett, Oregon
You should not be able to "spin" the rotor while holding the drive gear. The gear is held in place by a roll pin, located in the "collar" of the gear. The rotor is indexed to the shaft by a "dog" cast into the rotor.
There should be some movement between the gear and rotor, due to the advance mechanism.
Roger Carter
There should be some movement between the gear and rotor, due to the advance mechanism.
Roger Carter
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Thats what I thought. Its not just a little movement, I can spin one side completely around while holding the other stationary. Makes a nice little grinding sound when it does so as well.
I think I know why too. The timing chain set I replaced was the OE set and EXTREMELY loose. With both gears seated fully back I could almost slip the chain off the crank sprocket without moving the cam sprocket at all. I am actually confused as to how the truck ran. I am sure that this looseness is what broke the distributor.
I think I know why too. The timing chain set I replaced was the OE set and EXTREMELY loose. With both gears seated fully back I could almost slip the chain off the crank sprocket without moving the cam sprocket at all. I am actually confused as to how the truck ran. I am sure that this looseness is what broke the distributor.
Logistics Pro
Joined: Mar 2005
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From: tujunga, calif
That is strange, I've never heard of one breaking, what could possibly cause that? Be glad it's not the pin, if the pin sheared it is caused by a major problem.
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Yeah I don't know what happened or how the truck even ran for that matter. I've just been in the process of freshening up the motor, resealing, etc and I didn't even think to really look at the dizzy when I pulled it out. Just yanked it and set it aside. The truck ran relatively well actually.
And where it broke is weird too. It looks like it broke directly beneath the main plate the rotor rotates above (not sure what the actual name for this part is...) Hope that makes sense.
Perhaps one of my buddies that was over stepped on it or something... lol.
Oh and what do you mean be glad its not the pin? Just curious.
And where it broke is weird too. It looks like it broke directly beneath the main plate the rotor rotates above (not sure what the actual name for this part is...) Hope that makes sense.
Perhaps one of my buddies that was over stepped on it or something... lol.
Oh and what do you mean be glad its not the pin? Just curious.
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Logistics Pro
Joined: Mar 2005
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From: tujunga, calif
I've only seen a sheared pin once. It was caused by the oil pump coming to a stop..LOL. Later inspection found a small piece of metal in the oil pump gears. When the pump stopped it twisted the pump drive rod but it didn't break, the force of the cam gear still trying to turn the dizzy sheared the pin.
Logistics Pro
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From: tujunga, calif
I was just thinking, and someone will correct me if I'm wrong, but I'm assuming you have a dizzy similar to the earlier ones I'm use to working on. Take the rotor off and look down the center of the shaft and see if there is a felt looking thing, that for upper bushing oiling, remove that and see if there is a small snap ring that holds the cam assembly down onto the shaft.
Logistics Pro
Joined: Mar 2005
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From: tujunga, calif
There is a tool you can buy to do that. I have used a 1/4 drive and socket but be extremely careful LOL. Why do you want to prime it, is it a new engine or just been sitting for a long time?
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. Just wanted to get some oil flowin before the initial startup.