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Discussion Starter #1
I have a 850 dbl pump with dual 6.5 power valves on a 355ci with 244/250 @0.50/ .503/.518 solid cam, victor jr., sportsman II's - engine has vacuum can on 85 camaro as vacuum is low at idle - have to stomp on brakes if left idling low and then move off ( sometimes) has good lope

engine at top end runs as if over carbed (on 700r4 and 4:11 rear) as if its a slow builder is my best description

I changed the jets around, as I can't change carb now, to 78 primary and 80 secondary with 37 shooters to compensate (from 31 originally); left 6.5hg power valve on primary side and added 3.5hg to secondary - ie. to limit the effect of enriching mixture on secondaries to ease overly rich condition at top end

its my reworking of holley supertuning book theory on power valves

?? if my engine is over carbed on top end, what do you think of my newly hatched plan in addressing this problem

Be gentle!!
 

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I will try to help. An 850 DP. is a terrible street carb even on a big block. You are definately over carbed. Changing the sec power valve will do nothing as soon as you open all 4 barrels your 355 will have almost no vacuum so the 6.5 and the 3.5 will open at the same time. Did it run better when you leaned down the primary I bet it did. Go back to the orgional squirter if it stumbles then go bigger one. Try not using the whole carb when you accelerate just half throttle until the RPMs get way up I bet it runs better. When you can get anything else do it I bet it would run better with a vacuum sec 600 than it does now.
 

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Discussion Starter #3
Thanks for your reply but I never got to check my plan on the road - fuel bowl gaskets have decided not to seat - may be a slight warp

so I have put back on my edel 600 cfm

I know that a smaller carb would work better on my car but the 600 has leaned out on me at 5500 and I am not yet able to understand fully the "recalibration" of edel's which seems rather complicated compared to the 850

I am hooking up a holley fuel pump to see if I have a fuel flow at high rpm problem
 

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You have WAY too much carb, and your primaries are WAY too rich. If you have to keep it (once you square away the gasket problem), drop the primary jetting down to 72 and work up from there (if you have to).

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JohnZ
'69 Z28 Fathom Green
 
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