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Old 04-24-2013, 12:49 PM
eric32 eric32 is offline
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Yeah this carb is only a 2 corner idle adjustment. Seems the carb is not too compatible with bigger cams then rv sizes. Can't afford a new carb right now and want to do what I have to do to make this one work and I just need to get it fine tuned to do so.

Problem is if I open the secondary's to be equal with the primary's it ends up with too much of a high idle and causes off idle slow speed surging issues but fine once rpm is picked up. Using ported vacuum does make my engine run with a little less throttle response on low speed and also makes it run a little hotter through town in stop and go situations.

But the primary's I can never get to be .020 or close to it without having to open the primary's open more in order for it to idle good and not stall when put into gear but defeats the purpose of getting it to be square and not end up with the idle pulling too much from the transfer slot and making a too rich of an idle.

This carb has a very lean idle circuit and that's why I asked if I use the billet quick fuel metering blocks it has replaceable idle feed restrictions and will allow me to change the idle fuel curve and might allow me to get better adjustability as this cam want's a richer fuel curve in order to idle well.

From what I read the holley 1850/80457 600 vacuum secondary carbs and there street avenger lines are set up with a very lean idle circuit and many people have had problems with these carbs being way lean out of box on anything other then a stock size or rv cam engine.

Even if I give it more timing initial and hooking the vacuum advance up to ported source it does not make any difference and I end up with the primaries open too much but the idle mixture screws still adjust but end up with run on after you shut the engine off.


I have not checked how much vacuum I have but should be around 16 inches so that is not a problem there as far as vacuum signal goes.
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