131mirafiori forum

Can anyone suggest where to start , I have 1600tc with 32adf carb , used service kit on carb , now the carb will only tick over , once it runs upto 3000rpm , it cuts out with a sucking noise . I have plenty of fuel in float chamber so is it obvious that I am short of air somehow?. Parts replaced are jets , throttle pump , pump diaphragm needle valve and gaskets . Pin in float chamber is a lot looser than old one ?, but seems like it can not really fallout?.  Any advice would be appreciated. ???

Check for holed float ?  take it out and shake it and see if there is any fuel in it. have had this happen a couple of times. You can convert 1600t/c  to 34 adf but you will need 2000 manifold as ports are larger and it will go better.

Why did you replace jets? They're not part of a service kit. Everything has to go back in the same place they came out from. If you mixed up idle jets, mains, emulsion tubes or air correctors you'll have issues. Are you getting a squirt of fuel from the pump nozzle into the primary when you move the throttle? Did you set the float level? Can you slowly raise the revs passed 3k/rpm in neutral?

The Float seems ok , its a bit dented but no fuel in it and was working ok before .Fuel level in float chamber seems ok . I replaced the jets with the same size as were fitted originally , thought it was an easy thing to do and would make things better . I replaced throttle pump because the nozzle which faces down was broken off . There is flow from pump throttle when you open throttle. Not sure if it matters but when engine was running I put hand on top of venturi`s there was a very strong suction to the extent I had to drag my hand away and engine cut out . I was wondering if this was normal ? , did not notice this before , made me think I needed more air also sucking noise when engine cuts out . In neutral unable to go above 3000 rpm without engine cutting out?. If short of air do I just need to adjust air/ fuel mixture screw?.

The adjustment screw usually just adjusts the mixture at idle. If the car idles I doubt adjusting this will cure the fault you describe. If it ran ok before the chances are it is something you've done when working on the carb although sometimes coincidences happen!

Always start with the simple things is good advice. Check all the basic things that could cause this type of issue.

If you are sure you put same size jets in etc etc  and the float height is good then try checking for an air leak at carb base ( use a squirt of easy start around the suspect area with enging on tick over, revs go up you have an air leak, simples!) could be that with the leak making the mixture weak, once you ask for more revs, there is not enough of the good stuff to go round and yes the engine will die and give that sucking sound, if your quick enough you can sometimes catch it with a couple of pumps of the pedal to make the accelerator pump artificially richen up the mixture before the engine dies completely. If you dont really want to start spraying inflamable gas around your engine bay, on tick over try turning the mixture screw. Start at a nice base setting of say 1.5 turns out, then keep turning it out (richens the mix), if the revs come up and keep on climbing till nearly fully out its running lean. If not, go back to the 1.5 turns out and try turning it inwards, weakening the mixture, again if revs increase then your running rich. Make all adjustments in small increments. Hope that may help. G

PS yes if you put your hand over the carb with the engine running it will suck like hell, it has to get its air from somewhere and as your starving the engine of air, it will stall as the mixture is to rich.

Thanks for the suggestions , guess  I will just have to take it all apart at the weekend . The engine was running ok previously but not very smoothly , I knew gaskets and throttle pump were broken so thought that it would improve things by using service kit?, seems I was wrong!. My only thought with the sucking noise was if it starts at around 3000rpm then this would be when secondary was opening so could the problem be something in this area . Probably find its something I did wrong , annoying as I had no such problems when I took the carb out last year .

Are both chokes opening properly as they should?

Unfortunately no garage and working too much so I will check at the weekend , but I think that the secondary was sticking a bit more once the carb was fitted compared to when I had it off ?. Also I think when I had carb running at the weekend there was some small amount of liquid/fuel? on top of base section at rear so maybe that is my leak , if so what is best to seal with will instant gasket do or is there something better to use . I have tried to put back as I found things but might have made the mistake of cleaning all surfaces , should I reseal all gaskets with something to ensure a seal?. Also the base spacer , on top of inlet manifold, only had gasket next to manifold and not one between the spacer and the base of the carb , should I have one or not , did not get one with kit . Sorry if these are stupid questions.

Carb gaskets are usually assembled dry. The inlet manifold to head joint (if you took the manifold off) can be assembled with gasket sealant.

Had a look at the weekend , the main jets supplied are slightly different in design and although they both say they are the correct size one fits better than the other and when swapped around engine ran very much better . Seems the one which does not quite fit as well will not work on the secondary at all but will do a partial job on primary . Full rev range available when I swapped them around although refusing to idle but I think chokes need resetting . Any thoughts about slightly different shaped jets?, I am going to contact suppliers and get replacements sent out .No apparent leaks and as it ran very well when swapped round I will try and get matching pair!.

 ???

Put the original jets in and leave them there. Absolutely no reason to replace them unless you want to change jet size.

ebay item no;; 271436804295.  ( i dont know how to do links)

I was very lucky found a new 32 ADF carb on ebay for one of my Super last week, was a bit of a find :)

(http://i739.photobucket.com/albums/xx34/minicacj/Mobile%20Uploads/photo_zps2caea31e.jpg) (http://s739.photobucket.com/user/minicacj/media/Mobile%20Uploads/photo_zps2caea31e.jpg.html)

Engine is up and running !. I think that the choke was sticking so I have positioned cam to it does not open throttle up when starting , starts fine and runs a lot quieter , but on a long run noticed loss of power at top end , I assumed that the secondary jet was not opening . Having checked on the drive running engine up to 4500rpm does not open the secondary?, what revs should it open at and how do I adjust to make it I have lever mechanism on top of cam . Not sure if this is enough info , engine is running a bit rich at the moment but I don`t think this matters. The secondary does open if you move throttle by hand with engine not running , decided it should open before this point so stopped. As before any advice would be appreciated .

The secondary opens due to throttle position rather than revs. If you ran it up to 4500 revs without load the throttle may not have been open far enough to open the second choke. Do you have a rolling road facility nearby? It might be worth spending a bit on a rolling road session where you can get everything set up correctly with the engine under real life conditions.