timing keeps moving
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timing keeps moving
my 79 f 250 400cu in seems to have jumped time. I put the light on it and got it back to 10 deg. turned it off to remove the light and when i restarted it the timing was off again. what could cause this?
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Is it possible the timing is out and the throttle plates are uncovering the ported vacuum holes causing the vacuum advance to be changing the timing as the vacuum fluctuates? This was happening to me.
Simple check is to disconnect the vacuum advance hose, plug and see if the problem goes away. Or check the ported vacuum at idle. Should be zero to 1-3 inHG.
If either is true you have a carb tuning issue, not a mechanical problem. Worth a check before heavy repairs.. I don't have a 400 but 10 deg seems high. High timing could cause the scenario above...
Simple check is to disconnect the vacuum advance hose, plug and see if the problem goes away. Or check the ported vacuum at idle. Should be zero to 1-3 inHG.
If either is true you have a carb tuning issue, not a mechanical problem. Worth a check before heavy repairs.. I don't have a 400 but 10 deg seems high. High timing could cause the scenario above...
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From: Cave Spring Georgia
Do you have the nut tight that holds down the dizzy? Mine was loose and causing the dizzy to turn.
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when I moved the dist and got the timing to 10 deg it sounded smooth and the vacume guage read normal. I shut it down and removed the light and when I restarted , it was worse. The short block is only a few years old, but I might have had to use the old har. balancer when I put it in. Only 18,000 mi on engine so I would;nt think chain is shot.
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From: Cave Spring Georgia
I would not think with 18 thousand it would be bad. The only thing I can think of is:
1. Bad timing chain
2. Loose dizzy
3. Possible bad gear on bottom of dizzy.
You are checking the timing with the Vac timing advance line disconnected and plugged. It should also be on ported vac to the dizzy. No Vac at Idle
1. Bad timing chain
2. Loose dizzy
3. Possible bad gear on bottom of dizzy.
You are checking the timing with the Vac timing advance line disconnected and plugged. It should also be on ported vac to the dizzy. No Vac at Idle
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