Race Engine Forum UK

Hi
Can anyone help me with those carburetors.
First thing is what are these for :




1 and 2 is on both carbs , no 3 is only on one.

Second thing - jetting chart, this is a current one :
Choke 32
F11 tube
Main Jets 140
Air Correction 175
Idle 55
Pump Jet 45

Will it work with stock 2.0DOHC Fiat 132 engine?

Do i need velocity stacks or i can fit only 2 x45mm air filters on top of the carbs ?

What type of Fueal pump is the best for that. Can I use facet silver top pump ?

HOw many psi and how much fuel flow these carbs need when used with stock engine?

Thanks
Andy

1 is choke (fuel enrichment) control arm

2 is vacuum pipe connection for air filter box

3 is fuel return pipe to petrol tank

Thanks

But if the fuel will return just after 1st carb the second will get less petrol ??

What about the fuel and jetting ?
I have currently fuel injection pump that gives 1.1bar and 65 or 85 ltrs , so i defenetly need a carb pump + pressure regulator , i was thinging about 4-6psi pump + regulator to keep it 4psi. But i dont know is it good or bad :/

Andy

Andy, hi

I like your little post with the annotated photos! Nice and clear.

Yes the carb fuel return can draw off too much but this only happens when the pump is of insufficient capacity or worn out. If you are running a mechanical pump it's best to keep the return line - if already installed in the car - because it allows the fuel to circulate and stay cool in the fuel line and carb. That is only a problem with mechanical (block mounted) pumps though: without a return line the pump suction causes low pressure in the delivery line from the tank and at altitude on a hot day the fuel can boil and the engine will stop.

As you are going to use an electric pump the one you should use is the Facet Silver Top interrupter type. Buy the kit with its special mountings and unions. Don't use the 'competition' spec and certainly not the 'Red Top'. You do not need a regulator with the Silver Top, it does not produce so much pressure that it will upset the float needles. The pump should be wired on a fused, relayed circuit with cable rated same as the earth lead on the pump and is should be mounted in the boot so it's pushing not pulling.

Those jettings are OK for the stock 2 liter unit but the chokes want changing to 34 really.

Try a search by IDF too, there is a lot on this site about them,

GC

Hallo Mr Croft , it`s nice to meet You.

Thank You for reply.

The only thing is which of silver top pump should i go for (probably the weakest one 4.0-4.5 psi, flow rate 18galls/hr up to 150bhp)

Do You know the diamensions of the pump ? Because i have limited space under the acces panel in boot

The other solution is the solid state "cubical" pump, but also I have no idea how big is this one.

Can I fitt the pump under the car ?

1. Facet Silver Top interrupter type.
2. Buy the kit with its special mountings and unions.
3. Don't use the 'competition' spec and certainly not the 'Red Top'.
4. Get it from the UK main agent FSE, internet search will find them.

I used these on TCs for 20 years. FSE will tell you everything else you need to know.

GC

Ok I got them
Which one is better ? The road of fast road version ? How much psi should be set on pressuere regulator if fast road used ?
THe pump have build in filter, shall i add another one under bonnet before carbs ? Can I use just external filter only without build in pump filter ?

Thanks
Andy

Ok the pump is sorted.
Now i wanted to buy synchrometer and air filters but :




1.The air correction jest are different is it a problem when i`ll be tuning the carbs ?
2. What are those cooper pipes sticking out from carbs ?
3. DO i need to buy another plate that goeas on top of the carb and then i fit filters ?
4. Do I need velocity stacks or just air filter ?
5. Why my emulsion tubes are not sticking out , on most idf`s thay do.

Thanks :)
Andy

Andy, you should have a pair of these to bolt on the top of the carbs

thanks bernie

Do You know where i can get these ?

Are they ok to fit ramflow airfilter which is about 51mm high ?

If those plates are hard to get can i just buy ram pipes to balance the carburetors and then take them off and fit filters? I hope it will work or i have to balance them with the ram pipes and run the car with them ?

Felga, if you can't find the stacks for your carbs, I may have a set. The only problem is I'm in the USA. The longer air corrector will make the carb more sensitive to tuning. I replaced mine because the end had worn down and I couldn't get any response when turning them in or out. The shorter one looks like an original from a 13/15 40 idf.
The brass tubes are mixture enrichment tubes. Fuel is drawn from the float chamber and is sprayed out of the tubes into the air horns to aid in acceleration.
Your emulsion tubes look normal to me. I haven't had the opportunity to work on anything but the early version of these carbs.

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GC

Guy,
interesting information on the Silver top interupter electric fuel pump.
Would i need to fit a regulator if i was to use a Silver top interupter on my 131 fitted with a pair of 45's?
Steve

No, absolutely not.

Provided the carb float level is correct and the float needle in good condition, neither the Silver Top nor Silver Top Competition Spec interrupter pumps will lift the needle off its seat on any carb I know of.


GC

Hi Guy hope you well,
Reading what you have said about using the silver top pump and not a
red top has got me a bit concernd,After talking to a company about that
i had a 2ltr twin cam with twin 40idfs and was thinking about uping the power in the future ie maybe you doing my cylinder head so they suggested a red top with a regulator which i purchased but will this give
me problems.
many thanks Andrew