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Carburator Conundrum

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    I will most probably be going for a Holley Street Avenger 570 now but my mate has offered to rejet the summit in the interim,just wondered you guys with 600's what jet sizes you had on stock 302's?

    Funny thing is rsk289 mentioning 4100 I was offered one free from a friend who imported a 66 Thunderbird rather than do a rbuild he just threw a holley on his and the 4100 is available if I want it?

    Would need a full rebuild though as the car was a non runner and hadnt run with that carb for some time.

    That one was off a 390 though...........


      To be honest I would go for the new 570 SA carb. At least your starting with a known quantity.


        Carb Update Guys

        While away on holliday I left the Mustang II with my Tame Mechanic to give him plenty of time at his leisure to fettle it.

        After a bit of a rebuild its come back with smaller jets and its no longer chucking out Bovril from the tailpipes
        Its a lot leaner now though I wonder if its just a smidgen too lean as though it runs great and pulls like a train its a little harder to start from cold and needs time to settle but once it had its transformed!
        So it looks like I dont need to buy another carb now


          Actually not running clean on immediate start up is a good sign in my books that the engine is not running rich. I am sure you will quickly develop a starting technique.


            All good advice above - with this owners club there's so much actual practical experience you're unlikely to have a problem that can't be solved with a thorough approach.

            I would add that, until you get chance to consider a rolling road set up, be sure not just to check the jetting - if you're not sure of its maintenance history give the carb a full once over to set up properly. There's an order to do things in, that I can't remember at present, but starts with basic mechanical adjustments and then progresses to running adjustments. It's very satisfying to tweak the carb to it's best like this.

            1. Does the butterfly plate open fully vertically on full throttle pedal push? - if not adjust the carb linkage so it does.
            2. With throttle fully pushed, push down on the accelerator pump lever and check the gap to the adjuster is 15 thou.
            (Adjustment is easier with 2 people and a small spanner to gently push the lever down.)
            3. Consider removing that auto choke and wiring the choke constantly open with a bit of solid wire.
            (You'll need a bit more throttle to idle in winter, but the engine soon builds temperatiure. )

            4. Adjust the front and rear float levels until fuel only just leaks out with the engine vibration when running.
            (Care needed here with fuel and hot engine!)
            5. Wind the enrichment screws in GENTLY until they bottom out, then wind each side back out 2 1/4 turns as a starting point, to obtain a smooth idle.
            (These are small screws and you don't want to break the head off.)
            6. Set the idle speed to obtain an idle of around 750rpm.

            This is from memory so I've probably missed something but will be a good thing to do for the re-jetted carb and your understanding of its workings.

            You can then fine-tune these settings based on your driving experience over the next few drives.

            Looks like that's what's been done then - great to have it running nicely I'm sure!
            Mine is running a Holley 600cfm with smaller jets and it's absolutely fine like that.
            Last edited by SurreyXedos; 06-04-2019, 11:48 AM.
            '65 289 "A" Code GT Optioned Coupe, with 4spd Toploader, lowered on Konis with export and Monte Carlo braces, and Arvinode exhaust - sounds great!