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Discussion Starter · #1 ·
Hey y'all.
I'm coming super close to the end of my long and painful 77 440 swap into my 86 w150 and am in need of help.  The engine wil sit and idle and rev all day until roughly 2200 rpm no load and in park. Past that it'll back fire through the the carb.  Under load it'll backfire and hesitate until the secondaries open up. All ignition parts are new, distributor, ignition box, plugs, wires, voltage regulator, coil and ballast resistor. Im running about 12 degrees timing (seems to live happy there and produce the most vacuum.  The engine was just rebuilt and the timing marks are bang on and the chain hasn't skipped a tooth on the gears. It has a mild Melling 
can with a Duration 204/214, Lift .421/.443. it has a edelbrock 1406 600 CFM carb with an edelbrock performer intake and it's tuned to the most vacuum it will produce at idle with 2.5 turns on the idle screws. Also has a brand new fuel pump and clean fuel filters. Any body have any insight to help me out?
 

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Well i think your problem is a fuel delivery issue... to lean.
A 600 cfm carb on a 440 is pushing those limits of fuel delivery.
When your secondaries open up... it works better because your dumping more fuel in.
You could richen up the main jets up for some improvement but your going to have problems going down the road eventually.
My first 440 I was running a Accel 750 cfm D.F.I. unit. It died on me at Pismo Beach. To get home I found a 650 cfm Edelbrock carb at some auto parts store. Stuck it on and it would lean out and run out of fuel on grades all the way home.
 

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Discussion Starter · #4 ·
That very well could make sense. I have a shelf full of q-jets I could install one and see what could happen. I have messed around to see what sort of CFM carb I'd use using the calculator on summit and it was right around 600 to 650 cfm. Only because I'm not planning on revving just farting around town. What CFM carb should I be running?
 

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Cumminsguy said:
That very well could make sense. I have a shelf full of q-jets I could install one and see what could happen. I have messed around to see what sort of CFM carb I'd use using the calculator on summit and it was right around 600 to 650 cfm. Only because I'm not planning on revving just farting around town. What CFM carb should I be running?
Well with your mild cam... you could get by with a 750.
That cam is pretty low lift.
Your 600 might still work... if you try bigger main jets.
 

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I read a formula at holley just the other day... Engine size X max RPM divided by 3456 for Higher RPM
use for regular day to day driving Engine size X rpm divided by 3456 then x0.85 

This gives you ideal CFM of the carb.
 

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the best way to get the right carb is by experience , so either you try different things/ carbs or you use other folks experience , you can calculate all day and still be way off .... IMO .

do put the timing light on it WHEN its having hick-ups , look for the timing jumping around , then look at the vac and mechanical advance in dizzy IF you see a problem , but I vote yes , too lean ..... rejet try again ... also richen the idle some , I use a sniff test , I go too rich , then back off a little ... test again ... a little rich with a 440 is going to be best overall ... ( we are talking carbs ) 
 

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Don't rule out a bad fuel pump. I had a brand new small block pump, that could only push2 to 3 PSI.
 

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ummm but when secondary's open it runs ok sounds like the bowl has fuel , agreed I'd also had weak pumps that were new ...
 
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