fine tune 351
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fine tune 351
truck fires right up,think holley carb is pretty close,timing close, vac.18steady, battery 12.7v-bad hesitation from idle, minor pop threw carb,alt light always on but all test say alt and reg. good,use vacgauge to adjust timing and carb but doesnt change much
Cargo Master
Joined: Nov 2009
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From: starship enterprise
Pop through carb is a lean condition. Off idle might suggest accelerator pump. What carb is it? Are your idle mixture screws set right? I had one do this and the throttle plates were open too far allowing it to idle in the transition circuit and causing a lean condition when the idle circuit phased out at light throttle. Slowly Close the idle mixture screws down and monitor the rpms; they should drop accordingly until the engine finally just dies. If the idle mixture screws won't kill the engine then you have a condition where idle fuel is not isolated within the idle circuit. This means as the throttle is open then the fuel used to idle is from the transition circuit meaning when at part throttle, it leans out due to the idle using the fuel from the transition. You end up with a lean condition off idle.
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holley
holley-4barrel-singlefeed-elec.choke-pri.meterigjet64-p/v65- paper says carb#0-80457s-truck[351 stock but headers and carb]put vac gauge on,seems like wide range of adjustment before vac changes much[timing and idlemix screws
Lead Driver
Joined: Nov 2006
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From: Pa.
The vaccum advance should have little to no effect on motor at idle .. To tune timing with vaccum gauge take it to max vaccum achieved and go down just a little then set .. If it becomes hard to start after the motor is warm with characteristics like a low battery bring the timing down a little more
Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Right when you first get on the throttle? just off idle?
Seems? it's either working or it's not, there is no inbetween.
Agree, vacuum advance has no effect @idle (if connected to ported vacuum) OP stated hesitation "from" idle, i assume that to mean just "off idle"
Seems? it's either working or it's not, there is no inbetween.
Agree, vacuum advance has no effect @idle (if connected to ported vacuum) OP stated hesitation "from" idle, i assume that to mean just "off idle"
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fine tune
sorry-i had timing gun hooked up,rev motor and marks on balance moved 1/2 inch or so. idles fine, startsfine, the sec. you hit throttle bad hesitation. slowly increase rpm its fine. little bit pop out of carb ,not much. closed throttle, not running, set acc pump .015 between adjust bolt and pump lever. no emission decal in truck-books say6-14degbtc i got it around 10degs. steady 18 vac gauge
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Post Fiend
Joined: Apr 2008
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From: Big Sky Country
If you've eliminated timing as the issue i'm thinking your mixture is a little lean just off idle, i'm an Edelbrock guy, you're running a Holley, i think Redroad runs Holley's so let him chime in....
Lead Driver
Joined: Nov 2006
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From: Pa.
but I have been thinking about it something with vaccum secondaries @$375 it will take some for me to get off the fence besides probably don't need to make that decision until September
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Senior User
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have elderbrock on my chevelle, dont no what possesed me to go with holley
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try that now, plug port on carb, i guess leave pvc open? have large port in rear of manifold maybe hook to that?
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no air pump, pretty striped down, pvc in 1 v/c,open plastic 90 in other wich i`ll hook to breather. manifol has large port in back,can i hook pvc to that?and plug 1 on back of carb