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Thread: Twin 40 help

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    Twin 40 help

    Hi all ...
    ive searched the site for this but can’t find the answers I need

    before spending my money on a rolling road set up I just want to get the carbs as close as I can.

    Also recommended rolling roads please ( Manchester area )

    my xflow ... not sure of the exact spec.. but it’s running 1300cc plus 40 pistons , fast rd cam , idles really smooth , ported head GT spec head with standard valve springs , vacuum less distributor.
    Electric fuel pump ...
    it does ‘breathe’ a bit out of the catch tank breather , the previous owner has put the block and rocker breathers into the same tank ( I’m changing this , putting the block into the rocker lid , then the rocker to the catch tank )

    carbs twin 40’s Weber’s bought s/hand told they were off a 1.6 xflow

    the car starts runs and ticks fine ... a bit of splutter/ hesitation when rev’d ( not a clean progression)
    on the test drive it stands off with not much power ...

    so ive had a quick look at the carbs which I will update the sizes
    the chokes are 30 , 45 auxiliary Venturi and f7 emulsion tubes , main jet 115

    the rest ill I’ll have to get ...

    what should be in there please ..
    thanks Chris

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    Re: Twin 40 help

    you will need to list the idle jet sizes ( ??F?) to give people more chance.

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    Re: Twin 40 help

    Main jet 115
    F7 tubes
    180 air corrector

    45f9 slow running jet

    30 chokes
    45 aux

    Carbs numbered 144 & 151

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    Re: Twin 40 help

    Pump jet 40

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    Re: Twin 40 help

    Think my problem maybe the carbs are not matching numbers ��

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    Re: Twin 40 help

    Do they have ram pipes fitted?

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    Re: Twin 40 help

    Yes .. got 45mm or 55mm ram pipes ( set of each )

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    Re: Twin 40 help

    Have you set the float heights and fuel pressure?

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    Re: Twin 40 help

    Fuel pressure is ok ... floats I haven’t checked .. going to get a balancer

    Just thought the jets / chokes etc seemed on the small side

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    Re: Twin 40 help

    chokes are small, which is why the jets are also small

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    Re: Twin 40 help

    Quote Originally Posted by chrisb View Post
    Think my problem maybe the carbs are not matching numbers ��
    151 is a suitable carb for xflow, not sure about the 144 (never heard of a 144) - I would check to see if the progression holes in the different carbs are the same. If not, that will contribute to your issues.

    Matching carbs aside I would normally try F11 or F16 emulsion tubes.

    30 chokes will do upto around 105-110bhp ish but that's if you've got everything matched and your choke size and aux vents are giving a good signal to the emulsion tubes.

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    Re: Twin 40 help

    Thanks honky... I had a little tinker today with a bit of rubber pipe ...

    Got the carbs all sounding similar .. can hear A ticking sound as well as the hiss from 2nd carb

    After a little adjustment I got it to rev a lot cleaner and the sound ( bark ) was more distinct

    Waiting the loan balancer to turn up to make more accurate adjustments

    Honky if I changed to 32mm chockes to squeeze more power out of it .. with the f16 tubes ... I’ll have to increase the jets ...
    any idea on the sizes required

    Thanks Chris

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    Re: Twin 40 help

    Quote Originally Posted by Graham View Post
    chokes are small, which is why the jets are also small

    Hi Graham

    Could you point me in the right direction .?

    32 chockes .. etc
    Thanks Chris

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    Re: Twin 40 help

    ** CHOKES ... very tired

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    Re: Twin 40 help

    32 chokes will want something like a 135main

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    Re: Twin 40 help

    Balance isnt the issue, balance only really effects idle at very small throttle openings, i would set your float heights before doing anything, chokes are small but it should run ok

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    Re: Twin 40 help

    Quote Originally Posted by Erikmex View Post
    Balance isnt the issue, balance only really effects idle at very small throttle openings, i would set your float heights before doing anything, chokes are small but it should run ok
    Thanks Erik
    I’ve looked up the float levels , just need to take all the throttle linkage off again ...

    It’s been off that many times because of bonnet clearance issues..

    As you say the chokes are small so I am going to go upto 32mm so I’ll need to get new bigger mains and like honky said f16 tubes

    Thanks for your help

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    Re: Twin 40 help

    People think balance plays a big part in driving but it really doesnt, a 1% unbalance at a small say 5% throttle opening is alot but 1% at 50% is nothing, balance only smooths idle. Dont spend a fortune on jets, fit an AFR meter or take it to a rolling road, maybe buy new chokes and f16 e-tubes, some bigger mains and do the rest properly measuring AFR at load.

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    Re: Twin 40 help

    Quote Originally Posted by Erikmex View Post
    Balance isnt the issue, balance only really effects idle at very small throttle openings, i would set your float heights before doing anything, chokes are small but it should run ok
    Erikmex ... your right about my float heights ... they are both set differently
    Plastic type ... one is 15mm and the around the 22mm mark

    What should they be .. research I’ve found different measurements some say 15mm others 12mm

    Also what’s the bowl empty measurement.. can’t seem to find this

    Thanks for your help

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    Re: Twin 40 help

    From info I have on the 151 carbs the float should be set @ 12-12.5mm closed and 25mm open with plastic floats. Brass are 8.5mm closed to 15mm open.

    Although I'd like to think that all different Tipo carbs used the same size float chambers I don't know for sure as I've never compared any. That said, it'd initially make sense to have both floats in different Tipo carbs at the same height.

    It would be something to consider if problems persist that different Tipo carbs may well use different float heights even if using the same plastic floats.
    In my mind having different Tipo carbs would be playing on my mind until those questions are answered.

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    Re: Twin 40 help

    Thanks honky. I’ve ordered some jet drills so can check the progression drill holes are the same size in each carb.
    They are both ‘tipo’ But the 2nd one with the later number has some webbing on the top cover.

    Got myself an early Xmas gift to synchronise them .. ��

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    Re: Twin 40 help

    All DCOE carbs have Tipo on them, it is the "Tipo" number that is the difference. Each number equates to a base setting and intended use. IE as you found some carbs don't have a vent hole on the front face and instead use a castellated jet cover system instead. There will be other differences such as fuel drillings, progression holes etc etc.
    As an example Tipo 31 is for Lotus Twincam Big Valve, Tipo 34/35 for Hillman Hunter. The 34/35 suggests one carb has one setting and the other slightly different. I don't know what this is but the engine designers decided that they needed to be different for whatever reason.
    Ford never intended for two different Tipo carbs on the crossflow engine!

    Progression holes can be different in number, size and location. I would not drill any progression holes (if that is what you propose if they aren't the same size) if it were me. It takes a VERY accurate drill, being able to hold it steady and making sure you get them in the right place and even the angle. It's an expensive learning curve in my eyes!
    Last edited by HonkyWhiteTrash; 09-12-2018 at 08:35.

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    Re: Twin 40 help

    Quote Originally Posted by HonkyWhiteTrash View Post
    The 34/35 suggests one carb has one setting and the other slightly different. I don't know what this is but the engine designers decided that they needed to be different for whatever reason.
    If for a car/engine Weber lists different carbs, like 44IDF40 and 44IDF41 for the Pinto GP1 setup, the difference is in the linkage used and also in the fuelhose "pillars" .
    Settings like jetting and float level will be the same.

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    Re: Twin 40 help

    Quote Originally Posted by Miniliteman View Post
    If for a car/engine Weber lists different carbs, like 44IDF40 and 44IDF41 for the Pinto GP1 setup, the difference is in the linkage used and also in the fuelhose "pillars" .
    Settings like jetting and float level will be the same.
    Thanks for that info Leon, very helpful.

    I'd still be wanting to have a matching set of carbs to start with rather than ones with potentially different progression holes etc.

    Also of consideration if the carbs don't match is the pump jet spray - the pump jet actuating lever can have different travel / stroke therefore supplying differing amounts of fuel EVEN if the pump nozzles are the same size.

    Chris - worth checking the throttle pump stroke - you can measure the rod and how much travel it has when the carb top lid is removed.

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    Re: Twin 40 help

    Quote Originally Posted by HonkyWhiteTrash View Post
    Thanks for that info Leon, very helpful.

    I'd still be wanting to have a matching set of carbs to start with rather than ones with potentially different progression holes etc.

    Also of consideration if the carbs don't match is the pump jet spray - the pump jet actuating lever can have different travel / stroke therefore supplying differing amounts of fuel EVEN if the pump nozzles are the same size.

    Chris - worth checking the throttle pump stroke - you can measure the rod and how much travel it has when the carb top lid is removed.
    Ahhhhhh shi.... just put the covers and fuel lines and lineage back on .... doh !!!

    Anyway ... she’s running ... but upset ... tried to balance the carbs ... at first I was getting 6 out of each trumpet .... but the exhaust was popping ...
    I noticed one of the auxiliary Venturi’s had moved ( question related to this shortly ) so I undid the trumpet, spun it back and tried again .... NO POPPING ..
    However the reading on the lead carb is now only 3 - 4 and the other carb is reading 6 ... doesn’t matter how much i adjust them it won’t change .. no air leaks I’ve checked that ...
    the car ticks over and revs cleanly .. until I then ran out of petrol

    So what I’ve done .. reset the float heights , installed 32mm chokes , f16 emulsion tubes , 130 mains , 180 airs

    Looks like I’ve been really had over with these carbs .. there’s no way of locating the auxiliary Venturi shouldn’t there be a location peg that runs down the guide in the carb barrel.?

    Sorry to be a pain guys

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    Twin 40 help

    I

    This may help you might need to zoom it a bit to see etc


    Sent from my iPhone using Tapatalk

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    Re: Twin 40 help

    From the quick I had at mine before fitting them into my carbs they don’t have them spring clips
    I seem to remember seeing the drill indents to accept the locating screws .. however my carb body’s have brass plugs in the area where the screws would go in ...
    looks like someone has fitted the later Venturi’s to my early carbs

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    Re: Twin 40 help

    It could be that you've got Dellorto aux vents as they have a locating screw. Not familiar with Webers' having this set-up.

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    Re: Twin 40 help






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    Re: Twin 40 help

    As you can see from the photos
    The Spring clips are missing .. And has one small drill indentation

    Brass plug has no screwhead..

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    Re: Twin 40 help

    Early Webers had the blanking plug - that is put there after the main fuel delivery gallery is drilled as it's the only way to get through the carb. It's possible later Webers had a retaining screw there just like the Dellortos.

    I have looked at my Dellorto aux vents and they are externally different, plus they only have one "spar" when looking down them, Weber DCOE's aux vents s always have two.

    Looks like you need an early aux vent to fit your carb.

    Photos show a Dellorto aux vent on the left, and early Weber one the right in both photos:




    This photo shows the drilling through a Dellorto (Weber is the same, you just can't see it unless you removed the brass plug) :



    HTH

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    Re: Twin 40 help

    You got the wrong aux. venturies. You need the one with clips. Taking out the brass plug is not a direct option The hole created is bigger as the plug that should fit. It can be done but better trying to find the right aux. venturies.

    With the other aux. venturies you will also need other trumpets. They are part of the support, keeping the aux. venturies where they should be. Otherwise they vibrate and worn out. (incl. carb bodies)

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    Re: Twin 40 help

    My trumpets do slide inside the carb body taking up the slack in the Venturi’s

    Only option is the buy the CORRECT early ones @£25 each...

    Anyone want to kick me in the nuts whilst I’m down ...

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    Re: Twin 40 help

    Quote Originally Posted by chrisb View Post
    My trumpets do slide inside the carb body taking up the slack in the Venturi’s

    Only option is the buy the CORRECT early ones @£25 each...

    Anyone want to kick me in the nuts whilst I’m down ...
    Since you asked - you really ought to get yourself a matching set of carbs rather than trying to make it work with what you've got.

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    Re: Twin 40 help

    Low blow ... thanks honky lol .. set of matched DCOE 31 went for £200 on eBay that needed work

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    Re: Twin 40 help

    Quote Originally Posted by chrisb View Post
    Low blow ... thanks honky lol .. set of matched DCOE 31 went for £200 on eBay that needed work
    Sorry, couldn't resist! £200 for 31's is quite cheap now, don't see them at that price very often. I bought some so-called refurbed ones recently for £400+ which ended up being utter tat.

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    Re: Twin 40 help

    Quote Originally Posted by HonkyWhiteTrash View Post
    Sorry, couldn't resist! £200 for 31's is quite cheap now, don't see them at that price very often. I bought some so-called refurbed ones recently for £400+ which ended up being utter tat.
    Got any spares to sell then lol ... I got outbid at £175 ... they hadn’t been used for years and looked rough...

    I gave £250 for these with the xflow manifold..
    new chokes , jets , trumpets , and now the auxiliary Venturi’s they are going to owe me over £450 plus

    May just stick the twin choke back and sell the bloody lot

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    Re: Twin 40 help

    Quote Originally Posted by chrisb View Post
    Got any spares to sell then lol ... I got outbid at £175 ... they hadn’t been used for years and looked rough...

    I gave £250 for these with the xflow manifold..
    new chokes , jets , trumpets , and now the auxiliary Venturi’s they are going to owe me over £450 plus

    May just stick the twin choke back and sell the bloody lot
    Sorry I can't help - I haven't got any parts as the carbs were sent back! I feel your pain - people just don't like being straight do they!

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    Twin 40 help

    Quote Originally Posted by wildo105e View Post
    I

    This may help you might need to zoom it a bit to see etc


    Sent from my iPhone using Tapatalk
    If you ever get to the point of new carbs. The ones above are dcoe31 I was going to fit on my lotus tc. In truth the dellortos I have on run fine. More than welcome for any inspection etc. You are fairly local.Nothing to hide on these.

    Not a hard sell but if you need give us a shout.


    Sent from my iPhone using Tapatalk

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    Re: Twin 40 help

    Quote Originally Posted by chrisb View Post
    My trumpets do slide inside the carb body taking up the slack in the Venturi’s

    Only option is the buy the CORRECT early ones @£25 each...

    Anyone want to kick me in the nuts whilst I’m down ...
    The aux. with clips you will find have flange at the end to support into the bore, the trumpets will not go over them.

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