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Thread: Removing Choke Butterflies from 32/36

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    Bodger

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    Removing Choke Butterflies from 32/36

    I wanted to know if a jetted 32/36 weber on a pinto with the chokes removed would have significant gains.

    1: would the removal of the chokes hinder anything? e.g start up, high speed, idle?
    2: would removing the chokes with out jetting make any difference?
    3: what if i just go for bike carbies?

    and what bike carbies are the best to go for? include years please.
    I want to start of with cheap mods and then go crazy with a ported head and cam etc.

    should i skip the jetting of 32/36 and go bike carbs?

    I ask a tonne of questions on here because i want to get things right the first time and not have to go back and do stuff again.

    thanks

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    Re: Removing Choke Butterflies from 32/36

    ok been there done that, if you remove the choke flaps, you will need to pump the throttle to start the engine cold, and keep it alive until it warms up a bit and you will have to put up the stalling spitting back until about half way warm, but yes it does give a performance gain.

    you could go half way, remove the choke spindle cut it in half and reassemble with a flap in the primary barrel only, like this it will start and run as normal as long as you are gentle on the throttle until its warmed up, i did that with my capri many years agao it it was quite manageable.

    this is a good cheap starting mod

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    Bodger

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    Re: Removing Choke Butterflies from 32/36

    thanks i will try that when i get to it.
    I have of people just getting a piece of wire and holding the choke open.
    i dont want to do that as it seems a little dodgy.

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    Re: Removing Choke Butterflies from 32/36

    pointless getting bike carbs (or dcoe etc)untill final spec is reached unless you can get em re-calibrated /rr tuned on the cheap

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    Re: Removing Choke Butterflies from 32/36

    Quote Originally Posted by MK1 CAS View Post
    I have of people just getting a piece of wire and holding the choke open.
    .
    cant see that achiveing anything any good

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    Re: Removing Choke Butterflies from 32/36

    Been there done that as well, and removed just the choke flap on the secondary barrel. Performance gains will be very marginal if any.

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    Re: Removing Choke Butterflies from 32/36

    what will give a much bigger gain is to remove the aux vents, if you look you will see one of its legs is hollow the other solid file down the solid leg so its around 1mm thick, this will add considerably to the amount of air the carb will flow, and make choke flap mods more worthwhile

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    Re: Removing Choke Butterflies from 32/36

    ............................
    Attached Thumbnails Attached Thumbnails D56C2FB4d01.jpg‎  

    bell_dual_throat.jpg‎  

    STD carb flow.jpg‎  

    Take it Easy....

    Roger Miller

    Works-Escorts = http://rsmotorsport.com.au/

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    Re: Removing Choke Butterflies from 32/36

    yes roger they are well worth it, unfortunatly they mean no choke flaps at all

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    Re: Removing Choke Butterflies from 32/36

    FantasticO!!! I've been looking for these babies ever since reading Vizard's bible. Was thinking about putting plasticine on the dgav but wasnt sure if it could potentially crumble off into the throat!

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    Re: Removing Choke Butterflies from 32/36

    The reason i ask about taking the butterflies off is because you rarely hear of people doing major mods to a 32/36 for street use. (class restricted race engines exempt).

    I have heard that a 32/36 can match a single 45 for power with stuff like a fast road cam and higher compression. so why arn't people keeping the 32/36?

    i think i want to keep my 32/36 and find some decent mods for it too. but i don't know where to start. I thought the choke thing may be a good start but it sounds like it does nothing... the reason i thought of this mod is I have a manual choke setup on my car and was going to fit auto choke from an Xf falcon (80's aussie ford). so thinking that i could get rid of the chokes all together would make life alot easier.

    So where to from here with the 32/36, genuine mods that i can do and can get a mechanic to perform. I currently have standard cam and compression.
    my carby was rebuilt about 12 months ago. so its pretty fresh.
    Last edited by MK1 CAS; 09-10-2006 at 01:41.

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    Re: Removing Choke Butterflies from 32/36

    the main reason the 32/36 is ignored is the 38 dgas!

    in thoery the 38 dgas is a much bigger carb, 2 38mm throttles compaired o a 32 and 36, but if you look a bit deeper you will see that the 32/36 has 26/27mm chokes and the 38 has a pair of 27mm chokes, this in practise means the 38dgas wont actually flow much more air than the 32/36, and if you get the wrong variation the low speed progression stuff is crap,

    where the dgas does score is with lumpy cams, having two sets of idle drilling means you will get a better idling motor if you have a hot cam.

    i had a mildly moded 2.0 renault years ago which i made a few mods on including 38dgas, when i sold it i put it back to the std twin choke,
    trouble was my mate bought it and and complained that it was dog slow compaired to when he used to borrow it off me , so i put the 38DGAS back on, then his wife complained, the throttle was too on off for her

    so i modded a 32/36 for it instead,

    removing the choke flaps was a non starter as it had to behave like std, but heres what i did.

    first off i bored the chokes out to 28/29mm i used a pillar drill but if you patient you could do this just with an electric drill and flap wheel,

    next i removed the throttle screws (best do only one screw at a time), counter sunk the holes and used some countersunk throttle screws from a weber 28/36dcd making sure to fit the screws with some loctite.then filed down any pertruding bits,

    next as described earlier i thinned down the solid leg of the aux vents to around 1mm maybe less, a power file was ideal but you could do it by hand.

    on guestimated jetting i refitted it to the car it went quite a bit faster than when it was on the dgas and miles faster than when on a std 32/36, i have no power figures but i know how much faster it went and what the speedo said and before it would comfortbly cruise at do 90mph but didnt really want to go much faster it would just scrape 100, afterwards that 90 criuise became 110mph and i remember seeing 126mph!

    add a stub stack and throw the choke flaps away and it would of been even faster

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    Bodger

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    Re: Removing Choke Butterflies from 32/36

    I ned to print this off, because i have no idea what is what and how to do this.
    So I will look for a 32/36 manual or diagram and start my research in the coming weeks.

    Thanks again for the help. I think i will stick it out with the 32/36 and try and get the most from it, i suppose for fun sake.

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    Re: Removing Choke Butterflies from 32/36

    other mods in a similar vein, if you have room height wise fit a couple of insulator spacers under the carb, this has the effect of making the carb appear a bit bigger as far as the engine is concerned, and if you a dab hand with the die grinder match the intake manifold to the head and where the manifold runners meet up put a nice radius around them so the mixture doesnt have to make such a sharp turn after its left the carb.

    once you've done this lot you should match the power you'd have from sidedrafts assuming you've still got a std engine

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    Re: Removing Choke Butterflies from 32/36

    I will also study the diagrams! I can't picture the aux vents... can you help me?

    Anyone know where to get the stub stacks in the 2nd pic of Rogers post? or the best stub stacks one can buy?

    Substantial info there Graham, the most satisfying mods are the ones you can carry out yourself!

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    Bodger

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    Re: Removing Choke Butterflies from 32/36

    The manifold mods sounds easy enough, Jetting the carb and getting bored out I will leave to an expert. do you think removing the aux butterfly with these mods above (the basics) will do much on a standard motor?

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    Re: Removing Choke Butterflies from 32/36

    every little helps as they say, but yes even a std motor is restricted power wise by the carb, just look at the 2.0 injection engine its got 15-18 bhp more than the carb'd version, ok the head is better, but not by THAT much, most of the power gain comes from the better flowing intake

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    Re: Removing Choke Butterflies from 32/36

    Cas, with the coppers and EPA and their crap here in OZ, I've kept my 32/36 on my RS2. I've removed the choke plates from both sides and went to 140 main/140 secondary jets. This has improved the response no end! I would like to find a stub stack to finish it off, but I can't find one over here. The RS is a daily driver, so I can't take it off the road for any length of time to have it fully dyno'd and tested. The right foot is the best way of determining economy! Keep off the 2nd barrel and you get resonable mpg.

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    Re: Removing Choke Butterflies from 32/36

    the chokes are just the tubes that sit in the shaft below the venturi's ? correct?

    can't you take the choke out all together? (stupid question i know)
    what is the best way to bored the whole shaft (primary and secondary to get more CFM or air)


    I was looking at a diagram and it looked a little different than i would have imagined. But

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    Re: Removing Choke Butterflies from 32/36

    please instruct
    Attached Thumbnails Attached Thumbnails inside_weber2.jpg‎  


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    Re: Removing Choke Butterflies from 32/36

    aux vents are no 5, they can just be pulled out after unscrewing the pump jet (3) your soon see which leg is hollow, chokes are 6, and dont come out you have to bore them in situ

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    Re: Removing Choke Butterflies from 32/36

    i understand the main jets are number 1 and are usually replaced to get better fuel flow.
    (can you drill them bigger? or are parts easy to get and find).
    whats is number 2 does that need to be replaced aswell to get better flow?

    since the chokes are part of the carb (i take it they are solid and not hollow) how far can bore them?

    is 2 mill the furthest or can you go ot 4 mill per side?
    Last edited by MK1 CAS; 11-10-2006 at 09:22.

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    Re: Removing Choke Butterflies from 32/36

    jets are easy to find, yes they can be drilled, they can even be soldered up again and redrilled if they are too big, but jetting is really the demain of the rolling roads, progressive carbs like the 32/36 are particulary difficult to jet at the roadside,

    no 2 are the air corrector jets, the adjust the mixture at the top end, without them the correct size mains for the mid range would give a horribly rich top end mixture, mains and air correctors need to be looked at together, for mild tuning goung up on the mains usually suffices but if you have to go a lot bigger on the mains you usally have to go up on the airs also.

    no dont try to bore the chokes 4mm, several reasons, you may find your carb ends up with a ventalation hole just where you dont want one!

    but also because to work properly the choke size has to remain within a certain size range of the throttle, or you wont have any real venturi effect which is the principle of how a car works in the first place, so 28mm really is the biggest size choke you want in the primary barrell, forgetting casting thickness for a moment the secondary choke shouldnt be more than a couple of mm bigger than the primary or you will have a nasty flat spot/ jump in the carburation and it will be horrible to drive

    it might not seem like it but boring both chokes 2mm is actually a big jump in size and airflow capabilities

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    Bodger

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    Re: Removing Choke Butterflies from 32/36

    I wanted to save abit of money so I think getting the jets drilled and the chokes bored (minus the secondary butterfly), get the di griinder out and do a jobby on the manifold; should be just what i need.

    Thanks again for the great answers and sharing your knowledge with me.


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    Re: Removing Choke Butterflies from 32/36

    no worries,m8!

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    Re: Removing Choke Butterflies from 32/36

    if you want to drill jets your self go down the model makers shop where you can buy packs of drills that vary from 0.5mm upto 2mm in 0.1 steps

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    Re: Removing Choke Butterflies from 32/36

    People who drill out jets should be jailed!
    The accuracy which the jets have been made is approx. 0,01 mm that's 1/5th of the thickness of a hair ... any bored out jets will have a tolerance of up to 0,1 mm or even 0,2 mm depending on the drills used.

    Boring out venturi's (chokes) properly is a difficult job if you want to keep some sort of smooth shape. Performance gains will be minimal especially if you keep the inletmanifold as it is and the cylinderhead is standard.
    Mounting a bellmouth like the ones RMinOz posted are a better option to get more air in the carb.

    If you do go the drill-out route, remove the number on the jet so you cannot make a mistake that it's a std one when you put it back in a box.
    Also if you dismantle the carb note exactly which jet, tube, aux venturi came from where as the DGV is a non-symmetrical carb. (the 38DGAS is).

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    Re: Removing Choke Butterflies from 32/36

    sorry but i disagree, the chokes themselves by way of nature are one of the most restrictive parts of a carb, regarding jets maybe new factory jets are drilled to a very fine tolerance, but float hieghts certainly are not set to anything like such a fine tolerence almost redering really accurate jet sizing a waste of time and there theres nothing wrong with drilled jets provided the sizes are determind by a rolling road or at least a plug chopping session,

    the same jet setting on new or drilled jets would be slightly different, but provided you get the motor set up with the correct mixture who cares if the jet is a 125 or a 127 or even 130 as long as the motor gets the right mixture, and seeing as no two motors are ever quite the same anyway all jet settings should be regarded as a starting point and fine tuned on the dyno anyway

    not that i know anything, only done it for 20 years and the man that taught me 20 years before that
    Last edited by Graham; 11-10-2006 at 23:33.

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    Re: Removing Choke Butterflies from 32/36

    now miniliteman comes in with a comment that rivals everything said above. Why make a statement like that, when I initially wanted to know how I can improve the 32/36 carb, if you know how to improve on it ina streetable way please let me know.

    graham: what is 125, 127, 130 and 140 jets in relation to (size wise) eg. mm, microns etc.

    how do I know I have reached the right bore for the jet?

    thanks

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    Re: Removing Choke Butterflies from 32/36

    cas, jets are sized in mm, 125 is actually a 1.25mm hole. everything i've said can and will improve the carb from a performance point of view and retain streetability.

    re jet selection of sizes, its a bit of a black art, sure you start with a "known" setting, i.e one that is known to work well on a similar setup, or one drawn from basic principles, or even experience, then you have to start the fine tuning, the best way to do it is the rolling road, but it can be done well by seat of the pants feel and plug chopping, plug chopping is wher you drive the engine under load for a while and without slowing down first you symaltainiously cut the ignition and dip the clutch, remove a plug and look at it, assuming the plug is of the correct heat range the plug colour will give you a good idea of mixture strength, chopping at different speeds and throttle positions you can pretty much sort it.

    now as i said before its very much a black art, the rolling road is the best way to set your carb and ignition up by a country mile, and i know it sounds a bit defeatest if you have no idea what you are doing with regards to carb jetting its highly unlikely you will get it anywhere near right, and possibly even risk engine damage trying to do so, so what i would strongly suggest is you merely go up a bit on the existing jet sizes to provide a safety margin against a dangerousnly lean mixture and get it to a rolling road.

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    Re: Removing Choke Butterflies from 32/36

    Graham B: I am not saying you are not a guru, and the mods to the carb that you describe can make some more bhp but only minimal in my experience and only if you know what you are doing and/or have a way to check the mods are effective or not. (flowbench, rolling road, dyno)
    I've seen so many people bolting on twin carbs and expect to have 170 bhp instantly only to find the engine has less bhp then it had as standard.

    When boring out jets, measure them with a jetsize-gauge. Especially when jetting 2 twin carbs as the jetsizes need to be the same for every cylinder.

    Cas: as an alternative to the plug chopping procedure I would like to suggest you fit a lambdasensor to your exhaust(-manifold), see pic as an example.
    Lambdasensors are not that expensive and on ebay you can buy the readouts for this sensor cheap as well. For my own car, and for diagnosing faults, I made my own LED-bar display. The high intensity LEDs are visible even in daylight. With the sensor fitted and hooked up to the display you then drive the car at several speeds/loads and check if the mixture is ok instantly. If the mixture is lean then fit a bigger jet and go and drive the car again.

    Regards, Leon.
    Attached Thumbnails Attached Thumbnails lambdadisplay_s.jpg‎  

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  32. #32
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    Re: Removing Choke Butterflies from 32/36

    actually i forgot all about using a lambda probe! strange because a wideband probe is the first thing to be attached to my cars before mapping!!

    i personally am a true convert to managment and modern methods, but also like to keep the old school stuff alive

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    Bodger

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    Re: Removing Choke Butterflies from 32/36

    I have thought of a Lambda sensor previously and I have checked on ebay oz for air/fuel meter.

    I take it the lambda sensor gets hooked up to the air fuel meter but does it need a power supply?

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    Re: Removing Choke Butterflies from 32/36

    although a lambda prode does generate a voltage its only small and confined to use as something an ECU can read, you will need a seperate 12v power supply.

    a note on lambda probes, you must use a wide band and even then most that are described as wide band are not that wide, not for getting these probes were origonally intended to checking correcting the mixture strength on modern engine managed cars fuel and burn efficent engines, the use of one that isnt truly wideband is limited on our engines which will generaly run quite rich mixtures.

    the reading of one isnt quite that straight forward either! light/part throttle and steady cruise you want a chemicially correct mixture, but the full power stuff needs to be a fair bit richer!

    and even then a lambda probe cant help with getting the timing right, i still say the best course of action is to mod the carb, go up a bit on jet sizes and get it to a rolling road.

    if you want a carb modded send it to me and i'll do it

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    Bodger

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    Re: Removing Choke Butterflies from 32/36

    I wish I could send it to graham as you are a knowledge bank.
    well doing some more research has brought me to this formula.
    firstly from the literature, if you are to go up in size for you main jets it is recommended to go up in aire corrector jets to to give the same air fuel ratio and not run too rich (get it wrong and you will run too lean).

    So here is the formula I found...Please let me know if this sounds right.
    If I curently have a 120 main jet and I go up to 135 the difference is 15.

    therefore with a ratio of 3:1

    15 * 3 = 45

    and if my air corrector jets were 140 they would not be 185 (+/- 10 depending on the tune of car).

    do you think the dude that wrote this is correct?

    I found jets for $8 each (air corrector and mains) what sizes would you recommend for:

    1) stock carby with exhaust manifold and 2 1/4 exhaust electric ignition?
    2) bored carby, matched and ported inlet manifold, exhaust system mentioned above?

    are the mods to a bored carby and stock irrespective of each othe ror will the bored carby thin the mixture too much and will require larger jets.

    I would like to know so I can purchase the right size for now and future mods.

    (the dude I bought the motor off used to have a tubo on it with the stock carb. but he reconditioned the motor and rebuilt the carby for non turbo use before he sold it).

    what are the stock jet sizes (main and air) so I know if the carb is in normal state or moded state, what marking do I look for, I am going to pull my carby apart in approx 14 hours. CAN'T WAIT!

    Sorry for all the questions.

  36. #36
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    Re: Removing Choke Butterflies from 32/36

    main jets have sizes stamped on the side of them, air correctors on the top edge.

    dont get too hung up on jet formula's, they are good when you dont have any sort of base setting i.e the carb is off a totally different engine, or the setup is miles away from another known jet setting, unless you are going to have to fit massively bigger main jets which you wont need to or rev the engine on miles further than std, which again your not just concentrate on the mains.

    also a carb is to a point self compensating, ie if you have one correctly jetted and put a head on which flows a bit better, more air will be pulled through the carb so you will get more fuel to go with it, its only if you fit a head which flows massivley more air or a carb much bigger will you really need to do much jetting.

    ford had a zillion different main and air corrector jet settings all slightly different, without taking emulsion tubes into account,

    but a std pinto would normally be jetted something like

    primary main 130-140
    secondary main 120-142

    air correctors somewhere between 130-180

    what has teh carb got in it now?

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    Re: Removing Choke Butterflies from 32/36

    Cas,

    I would leave the air-corrector jets and emulsion tubes as they are and experiment only with the main jets. (and maybe go up one size in idle jets).
    The wideband lambdasensor I have spends most of its time in a box as I find the info I get from a normal lambdasensor sufficient to set the mixture on carb-engines. But I think we had the discussion of what to use for a sensor more then once on this forum ...
    Things like the Gunson's Lambda System Tester can be bought cheap on ebay, see pic.

    Good luck! Leon.
    Attached Thumbnails Attached Thumbnails gunson_s.jpg‎  


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    Re: Removing Choke Butterflies from 32/36

    Quote Originally Posted by Miniliteman View Post
    Cas,

    I would leave the air-corrector jets and emulsion tubes as they are and experiment only with the main jets.

    Good luck! Leon.
    agreed, airs and correctors should stay as the as no drastic mods being undertaken,

    choke size will have virtually no effect on idle jet sizes needed so leave alone also ( cam has biggest effect on idles)

    i've a bit lost the plot as to how many of the suggested mods cas is carrying out, but if the chokes are being opened up bigger mains are a must 145 pri 150 sec should make a good safe starting point.

    dont forget when setting up you need to sort the primary barrel jetting first so wire up the linkage so you dont go into the secondary until your happy with the primary jetting

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    Re: Removing Choke Butterflies from 32/36

    Main Jets: Primary (127) Secondary (150)
    Air Corrector Jets: Primary (175) Secondary (145)

    Does this combo sound weird?
    Should I go up in primary main jet size to a 135 or 140. or will the 127 allow the car idle good.

    the secondary main is 150, so is that pretty big for standard set up?
    plus with the smaller air corrector jet won't that make it alot richer at higher revs? (I have been reading up on carbies).


    As for the mods, My vented disks are finished and sorted strut is now complete.
    The only other mods now include (full exhaust system), Electronic Ignition, Electronic Fuel Pump (Just the normal stuff to get a bit more power and better ride).

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    Re: Removing Choke Butterflies from 32/36

    main jet wont have any effect on the idle, that will be a seperate jet in the side of the carb bodies, most likely either a 45 or 50 either should be fine.

    as i said ford had many varied jet settings some a bit on the weird size but i dont think ford ever jetted a 23/36 with a 150 main so i huess it has been played with.

    the 145 sec air is very small, you would not normally have an air corrector smaller than the main jet,

    i would be starting out by changing the primary main to a 145 and secondary air to a 180

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