Transition slot restrictor baseline.

Fuel and Air Systems

  1. mderoy340

    mderoy340 Well-Known Member

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    Aug 2, 2012
    Melbourne FL
    Local Time:
    9:41 PM
    Anyone installed restrictors? What's a good size to start with? Proform 750DP 4 corner.
  2. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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    Jan 19, 2014
    South-Central Manitoba,Canada, 900ftelevation
    Local Time:
    8:41 PM
    On my carb I popped the plugs out of the Idle wells and dropped very small wires into the IFR at the top of the tubes. The smallest wires I had were too big. So I gathered up a selection, did some math, and drilled out the IFR a tad. Now I had an adjustable range. Got me to 32mpgUS on an 1850. Ok I cheated with a double overdrive, to get me a 1.97 final drive and 65=a tic under 1600rpm
    I plugged the tops of the tubes with rubber stoppers, and the air-cleaner house keeps 'em in place. At the top of every wire I made a loop. Changing wires only takes a minute.I keep spare rubber stoppers in the kit ,lol.

    Be advised tho, if you make the low-speed circuit too lean, you just end up opening the throttles further. Same for rear gears; if you go too small, you just end up driving deeper into the throttle. Gears works better tho cuz the rpm can be drastically reduced, so you end up burning less fuel per hour, even tho the the throttles are open further. But that kindof depends on the cam. The slower you run a 292/108 the worse mileage it gets. Mine wasn't too bad at 2600. Not good, but not horrible. But below 2000, well, that WAS horrible lol. I pulled that cam out PDQ.
    Spreadbores work great for this mod cuz you can get a triple-booster primary, and maybe get up on the mains at like 65=1350rpm. Yet once you get on it, there's lots of secondary.
    Just tossing out ideas
    Last edited: Sep 27, 2018
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