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-   -   What in a Holley carb would cause a mid range miss? (https://www.offshoreonly.com/forums/general-q/232372-what-holley-carb-would-cause-mid-range-miss.html)

whoya 06-09-2010 10:20 PM

What in a Holley carb would cause a mid range miss?
 
I finally swapped carbs after changing everything out in the ignition trying to find a miss.
My Holley 850 Double Pumper causes a slight constant miss when running in the 3800-5000 rpm range.
What would cause a miss in that range? To much fuel dumping in some how?
Fuel pressure was set right and levels to.

ezstriper 06-10-2010 06:26 AM

you could be on the edge of the power valve opening, lean at that point then opens and you are good, what power valve are you running ? should be a 6.5 but that can change due to cam, intake, etc...are you running a vacume gauge ? they are very handy....

whoya 06-10-2010 08:34 AM

I tried a 6.5 and a 5.5 with same results. Im showing a vacuum between 10-14 it would not stay steady at idle.

fbc25el 06-10-2010 08:55 AM

Do you know what your fuel pressure is in that rpm range?

whoya 06-10-2010 09:26 AM


Originally Posted by fbc25el (Post 3132228)
Do you know what your fuel pressure is in that rpm range?

I have a gauge at the carb and put another one on (to check while running)with a line and its holding fuel pressure in that rpm range. I tried between 6 1/2 to 7/ 1/2PSI no difference.

Im about to go buy another Carb.

Tow-N-One 06-10-2010 09:50 AM

is the motor supercharged, if so you need a boost refrence carb

whoya 06-10-2010 09:52 AM


Originally Posted by Tow-N-One (Post 3132271)
is the motor supercharged, if so you need a boost refrence carb

No, its a N/A 547CI

ezstriper 06-11-2010 05:52 AM

547 ci ? thats really taxing a 850, call patrick @ pro systems carbs, he set you strait !!! off the shelf carbs may not work well...Rob


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