pop&crack
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Freshman User
Joined: Apr 2007
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From: huntington
pop&crack
I have 78 with a 460 automatic it has a holley750 the disributer is been replaced a year ago with the plugs and wires . But one day i was driving and went to pass a car and when it comes on real good about 3500rpm it pops though the carb and will keep doing this untill you let off the gas. Ihave replace the power vale in the carb butt it wasnt bad.Any suggestions?
New User
Joined: Jan 2008
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Backfire through the carb is always bad ignition timing.
How many miles on this engine?
If a hi-miler I suspect worn out timing chain and gears and they need replaced.
also check the Vacuum advance on the distributor for being seized or diaphram being broken..
How many miles on this engine?
If a hi-miler I suspect worn out timing chain and gears and they need replaced.
also check the Vacuum advance on the distributor for being seized or diaphram being broken..
Post Fiend
Joined: Jan 2003
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From: Montana Territory
I bet the little hose that connects the distributor to the vacuum source on the carb (do not use manifold vacuum for the distributor) is cracked and leaking. While you are in there, its worth it to replace any suspicious hoses. Most parts stores have a variety of vacuum hose diameters available to choose from.
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From: huntington
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From: Piney Woods of East Texas
First indication is alway ignition, second it fuel lean.
Did you have it to the floor when this happened?
What model 750 Holly do you have? (mech sec or vac sec)
Have you checked the float levels on the bowls?
If it pop through the carb on the older model holly's you Blow the power valve.
Did you have it to the floor when this happened?
What model 750 Holly do you have? (mech sec or vac sec)
Have you checked the float levels on the bowls?
If it pop through the carb on the older model holly's you Blow the power valve.
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Joined: Apr 2007
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From: huntington
ok vacum secondarys ,i set the timing at 12degs \yes it is on the mat &the flots are fine & i checked the power valve it was fine, i replaced it anyway and total advance im not sure
