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  #1 (permalink)  
Old 05-28-2012, 10:40 AM
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Default Distributor set up

Using a Mallory uni distributor with a vacuum advance. can someone help with the setup. Car runs fine if I push the rpm's up slowly. If I stand on it I get backing through the exhaust. till i back off. thanks!!
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Old 05-28-2012, 11:13 AM
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wow.....ok....plugs,wires,carb,ignition box,rev limiter hit. the neighbors kid stuck in the sidepipe.......you'll have to give us more info there........
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Old 05-28-2012, 01:23 PM
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Plugs new, wires new, carb new, rev limit set at 5200, if the neighbors kid is stuck I'll kick his ass out for gettin the car dirty. We've narrowed it down to vacuum. floats set ,jets are 80's(holley), timing and valves all set to factory spec. can't get rid of the popping in the exhaust when you stand on it. Mallory site says to backoff the allen set screw in the vacuum advance to two turns and adjust from there. Thats where I'm lookin for guidance. Thanks!
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Old 05-28-2012, 01:28 PM
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Disconnect the vacuum advance, plot the existing timing versus rpm with a timing light, advance the timing 2 degrees at a time to see how the engine reacts.

Report back with your advance curve from the above and supply the engine specs.
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Old 05-28-2012, 01:37 PM
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Quote:
Originally Posted by jlb169 View Post
Plugs new, wires new, carb new, rev limit set at 5200, if the neighbors kid is stuck I'll kick his ass out for gettin the car dirty. We've narrowed it down to vacuum. floats set ,jets are 80's(holley), timing and valves all set to factory spec. can't get rid of the popping in the exhaust when you stand on it. Mallory site says to backoff the allen set screw in the vacuum advance to two turns and adjust from there. Thats where I'm lookin for guidance. Thanks!

i agree, disconnect advance first and see.......have you hung a vacuum gauge on it?.......do you just have a vacuum leak?
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Old 05-28-2012, 01:49 PM
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doesn't change with or without a vacuum line. thats why i'm thinking I'm not getting any advance from the distributor
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Old 05-29-2012, 07:06 AM
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,jets are 80's(holley),

80's are....alot of jet....
I run 74 in the front and 82 in the back.
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Old 05-29-2012, 07:39 AM
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Exhaust popping is often caused by a lean mixture. Which Holley do you have? How are the secondaries set up?
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Old 05-29-2012, 11:41 AM
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Quote:
Originally Posted by jlb169 View Post
doesn't change with or without a vacuum line. thats why i'm thinking I'm not getting any advance from the distributor
What doesn't change, the timing or the backfiring?

Have you plotted the timing curve with a timing light?

What Holley are you running, CFM, list number etc?
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Old 05-30-2012, 05:20 AM
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Back to "have you hung a gage on it?". Do you know that you are getting enough vacuum out of the engine? Sometimes, with certain cams, you only draw a few pounds of vacuum and need to think about mechanical advance distributors.
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Old 05-30-2012, 10:27 AM
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Sounds like a fuel problem or ignition breakdown issue - but not vacuum advance. Too much vacuum advance while cruising along (light throttle) can cause a miss-like sensation but vacuum advance falls out immediately as soon as you punch it.
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