ADHA to ADFA retrofit

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paulc
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ADHA to ADFA retrofit

Post by paulc » Sun Jan 13, 2019 8:42 pm

When retrofitting an adfa carb from an adha, what do you do with the open vacuum fitting on the high idle capsule? I know it's not functional on the adha but is it on the adfa? Or just plug it? :?:
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bartigue
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Re: ADHA to ADFA retrofit

Post by bartigue » Sun Jan 13, 2019 9:37 pm

Depending on the ADFA some have the high idle system and some do not. There isn't anything necessarily wrong with using the system but most of them don't work any more; they rely on the 3rd and 4th gear switches in the transmission to function as well as the solenoid and tubing from the manifold and to the carburetor. If it all works, fine, if anything doesn't work then it will cause you some issues with idle control. Summary: not worth the trouble.

The ADFA in place of the ADHA requires only the fuel lines in and out, the water lines to the choke, and the vacuum line to the distributor. Secondarily you could run the emissions canister. You could also run the low pressure vapor line if you run the stock air filter, which no one in their right mind would do, so I assume you are not!
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Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
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paulc
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Re: ADHA to ADFA retrofit

Post by paulc » Mon Jan 14, 2019 12:15 pm

Just acquired the ADFA as first step. Need the single plane manifold next as finances allow.
I first have to rebuild the carb as it's in pretty rough shape visually but it's definitely rebuildable, mostly cleaning and replacing whatever isn't right.
What would be a recommendation for an air filter since I only have the stock OEM one right now?
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atruscott
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Re: ADHA to ADFA retrofit

Post by atruscott » Mon Jan 14, 2019 12:31 pm

Save the pennies for a K&N
1960 Autobianchi Bianchina Transformabile
1970 238 Camper OHV
1974 124 Wagon TC
1974 124 Special TC
1975 124 Sport Coupe
1976 124 Sport Spider (The Racer)
1981 Spider 2000 (The Resurrected)
1985 Pininfarina Azzurra
2017 124 Spider Abarth Elaborazione
paulc
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Re: ADHA to ADFA retrofit

Post by paulc » Mon Jan 14, 2019 12:38 pm

K and N, eh? I'll keep that in mind.

Back to the carb itself.
Any advantage/ disadvantage to attaching the EGR valve with the ADFA? We don't have any emissions requirements here so I'd just be concerned with it from a performance standpoint. That's about all that's left of the emission system anyway since the air pump and all it's plumbing was removed by the PO and I've removed the funky reed valves also.
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bartigue
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Re: ADHA to ADFA retrofit

Post by bartigue » Mon Jan 14, 2019 1:12 pm

Block off the EGR at the exhaust and you can just leave the head pass-through open.
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Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
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andy
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Re: ADHA to ADFA retrofit

Post by andy » Mon Jan 14, 2019 4:32 pm

bartigue wrote:
Mon Jan 14, 2019 1:12 pm
Block off the EGR at the exhaust and you can just leave the head pass-through open.
Yep, and if you are lucky enough for the the exhaust side EGR piping to unscrew from the exhaust manifold an oil plug fits perfectly to plug the hole in the manifold.
Andy Jossy
Medford, Oregon
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bartigue
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Re: ADHA to ADFA retrofit

Post by bartigue » Mon Jan 14, 2019 6:15 pm

...and if you can't get that thing unbolted cut the pipe and a cambox hold-down thingy fits exactly into the pipe. JB Weld it in place and you're done.
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Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
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paulc
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Re: ADHA to ADFA retrofit

Post by paulc » Mon Jan 14, 2019 7:52 pm

Anyone have a photo or description of the cam box hold down thingy :?
Is that it's technical name :roll:
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bartigue
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Re: ADHA to ADFA retrofit

Post by bartigue » Mon Jan 14, 2019 8:13 pm

"Valve Cover Thumb Screw" there are two on each cam box cover. They hold the cover down. It just so happens they are the same diameter as that EGR pipe, so you cut the pipe and leave about 2" from the exhaust side. Remove it from the head side. Cover the thingy with JB weld and shove it in that open pipe on the exhaust side. Let it dry for 24 hours.

Midwest sells them:

https://www.midwest-bayless.com/FIAT-12 ... ioned.aspx
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Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
http://fiat.artigue.com
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