Twin 40IDF on 1756cc Fiat Twin Cam

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Testament
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Joined: June 22nd, 2006, 7:47 pm
Location: Taupo, New Zealand
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Twin 40IDF on 1756cc Fiat Twin Cam

Post by Testament »

I'm installing a set of 40IDF's from a Fiat 124 BC coupe that I've had kicking around for some time onto the motor in my CC Coupe

Have the following setup at the moment but need to replace the Pump exhaust/spill valve? (right in the bottom of the float bowl) as one got damaged in removal and the other looks kinda blocked anyway. Pump jets themselves also look kinda blocked too so could change those as well.

anyway here is what I have in front of me atm - not all BC parts as I got recommended some different main jets and things a while ago, which I got - but might be wrong now I have the larger chokes/ I cannot really remember it was so long ago.

Engine compression ratio: 9.8:1
Cams: standard 15/55 55/15 ?
Exhaust: standard CC manifold to dual secondarys ~ 500mm long then 50mm from the collector

Carb specs
Chokes: 34mm (have the std BC 32's also)
air correctors: 180
emulsion tubes: F11
Main jets: 135 (have std BC 125's also)
needle and seat: 175
idle jet: 55
acc pump jets: 40
Pump exhaust/spill valve : 80
aux venturi: 45
Velocity stacks: 40mm bellmouth (also have the straight profile OE stacks)
Image

plus whatever these jets/tubes are? idle/acc/startup air something? - appear to be labeled E5 80

Image

they go here

Image

I see there has been quite a bit of discussion regarding IDF's so any advice would be greatly appreciated.

Thanks
Tom
Urbancamo
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Joined: August 8th, 2011, 1:04 pm
Location: Finland
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Re: Twin 40IDF on 1756cc Fiat Twin Cam

Post by Urbancamo »

Hi Tom.

Jets on your hand are starter jets for for cold enrichment circuit.

You might consider pump spill valves with lower number, eg. 55 or 30 for better throttle response.

Otherwise your jets seems to be good for starting point, but if someone has more specific information than me, please give us your comments.
You might fiddle with choke sizes, 32 or 34 mm, wich gaves you best overall performance is your preffered choise.

-T
GC_25
Marc
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Joined: September 28th, 2006, 11:45 am
Location: New Jersey ,USA
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Re: Twin 40IDF on 1756cc Fiat Twin Cam

Post by Marc »

Use the 34mm chokes if you have anything outside of stock cams or it will run rich.Jetting looks good,use F-11 emulsion tubes
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