Carb size

Discussion in 'Technical' started by Broncobru, Dec 8, 2015.

  1. Broncobru

    Broncobru Member

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    Thank you.
     
  2. baddad457

    baddad457 Member

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    You're build is similar to my 331, which has the Canfield head equivalent to the AFR165's. My comp ratio is 10.4 to 1 with SRP flat tops and 57 cc chambers. Cam in mine is a Ford Racing Z303. My induction of choice is a repop 3x2 setup with a mech progressive linkage (a 750 triple pumper:evilsmile:) I ran this for years with a mild stall converter C4 (around 2,000) and it never bogged down from a dead stop, in fact it's always had traction issues, even with 3.50 gears, trac loc and 295/50 tires. There's just no weight in the rear of these cars to bog down the car. I don't recall what cam you chose, but you may want to go bigger, afterall who uses their car as a daily driver ? Mine is tame enough with the Z cam to drive everyday (did so with it in an 89 Ranger for 2 years) If you want my advice, buy a "little used" Holley 650-750 VS carb (these look new, but were tossed by someone who didn't understand Holleys) for around $100-$150 and take it apart and change the powervalve and accelerator pump diaphragm (these two parts will go bad after sitting dry on a shelf), then tune the jetting to your car. Also get a secondary diaphragm spring assortment and use either of the two lightest springs, these will let the secondaries open a second or so after nailing the pedal, eliminating any chance of a bog (which would be doubtfull) and keeping traction issues under control.
     
  3. Broncobru

    Broncobru Member

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  4. Broncobru

    Broncobru Member

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    Thanks for the good advice. I though about 3x2 myself they look so cool ! Summit Racing has a complete set up for $2800.00 to rich for me right now.
     
  5. baddad457

    baddad457 Member

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    I hunted my setup down on the net and bought it from a guy in Indiana who had only run it for a year. Paid $1100 shipped. ($100 for COD shipping) Mine has three 250 CFM carbs, Summit's set has 350's I think. Throttle response is fantastic with the 250 cfm center carb, much like EFI. After tuning it to get the jetting correct, I haven't touched em in the past 12 years, other than to go up a couple sizes after adding 1" spacers under them. And it sits sometimes for a month between firing it up. I feed it a mixture of 93 octane-( 10% ethanol) and straight 91 octane premium, alternating between fillups. Definitely has the WOW factor every time the hood is raised, there's simply nobody else around that runs multiple carb setups.
     
  6. Broncobru

    Broncobru Member

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    Looks great! The first of the year I might do my on search for a set up like yours. What type of fuel pump are you using?
     
  7. baddad457

    baddad457 Member

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    You'll be surprised but it's a simple and cheap 30-35 gal/hr electric low pressure pump . I ran a Purolator this size for 10 years in my 89 Ranger, then went with the Mr Gasket of the same size. I had to replace that one a year or so ago (it lasted 6 years or so) but I don't recall what brand. 30-35 gal/hr is plenty enough to feed all three carbs at WOT both on the strip and the open road (don't ask) The only time it'll starve the carbs is when the inline fuel filter gets clogged. When it does that (rarely) I know it's time to replace the filter.
     
  8. Broncobru

    Broncobru Member

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    I've noticed that some guys on forum are going back to mechanical fuel pumps. Any idea how much HP it takes to run a mechanical pump? Did you use a fuel pressure regulator with the low pressure pump.
    Thanks.
     
  9. baddad457

    baddad457 Member

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    Don't know about HP demand, but there is a penalty to pay in the friction at the pump lever/eccentric. Also if your car sits for long spells between the times you run it, the fuel in the carbs evaporates, then you have to crank it a long time before the mechanical fuel pump refills the bowls before it'll fire off. Neither of which happens with an electric pump. You just turn the key on and wait a few seconds to let the pump refill the bowls before cranking it. I never have had to use a regulator with these pumps. They're all low pressure pumps with a more ideal flow rate suited to a carb.
     
  10. Broncobru

    Broncobru Member

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    Thanks for the good information. Can you suggest a quite low volume pump? Your ideas about fuel pumps is a good way to go. Isn't there a switch that stops the power to the pump if the engine stalls and the key is on? Have you used something like this? Is it needed?

    Thanks, Joe
     
  11. baddad457

    baddad457 Member

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    I went with a Professional Products #10700 last year, so far no problems with it. It's very quiet, you can only hear it run with the engine turned off. I didn't wire it with an automatic shut off, I've got a manual toggle switch controlling it. Not a bad idea to use an automatic cutoff though, I did use the stock Ford switch in my 89 Ranger when I did my V8 swap.
     
  12. dan gregory

    dan gregory Member

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    If it is mostly a street car,& sits a lot without being driven,consider the edelbrock 750.They say that they are easy to tune & with a solid base there are no bowls to leak or any of the other problems that go along with Holleys,just something to consider.
     
  13. quickshift

    quickshift Member

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    I have both (Holley and Edelbrock) and I still prefer a Holley.
     
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  14. Broncobru

    Broncobru Member

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    Thanks!
     
  15. Broncobru

    Broncobru Member

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    Thanks.
     

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