Tuning Dellorto FZD

[Toshi 975]

I have just acquired another Dellorto FZD 30.24 carburettor which I am going to make available at a reasonable price of £260 + postage. I have checked it over and it is in good clean condition.

 

[dangfiat]

I have just acquired another Dellorto FZD 30.24 carburettor which I am going to make available at a reasonable price of £260 + postage. I have checked it over and it is in good clean condition.
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How suitable is this for a hot(ish) 650 or 700? Planning on basically 650 or 700 (currently stock 126P 650), with uprated compression (10:1 or so) and a 40/80 cam with head/valves to suit.

Is this enough carb, too much carb? Also how easy is it to get different jets/venturis, & approriate throttle linkage?

Sorry for all the questions, very interested but trying to figure out what direction to go

 

[Toshi 975]

There is a great thread you can search out on this forum by a guy in Australia who goes by the name Bambino, a must read for anyone considering a Dellorto FZD. Also I am sure that Tom “the Hobbler” will be happy to give his opinion as he runs one on his car. Another forum member bought one off me quite recently, he already has one on his car but is so pleased with it that he wanted a second one in case he ever needed a back up. Jets are easy to get here from Eurocarb with main jets about £5.50. Venturi sizes only come on the size for the carb, unlike the 40DCOE types, so you would not change it. Throttle linkage is common to any make of carb and available from any carb specialist.
This carb sold within about an hour and will soon be on its way to New Zealand

 

[the hobbler]

There is a great thread you can search out on this forum by a guy in Australia who goes by the name Bambino, a must read for anyone considering a Dellorto FZD. Also I am sure that Tom “the Hobbler” will be happy to give his opinion as he runs one on his car. Another forum member bought one off me quite recently, he already has one on his car but is so pleased with it that he wanted a second one in case he ever needed a back up. Jets are easy to get here from Eurocarb with main jets about £5.50. Venturi sizes only come on the size for the carb, unlike the 40DCOE types, so you would not change it. Throttle linkage is common to any make of carb and available from any carb specialist.
This carb sold within about an hour and will soon be on its way to New Zealand

The FZD is, in my 'umble opinion' just about the best carb for "common sense every day" driving on a tuned engine. Easy to set up (I will happily pass on my jettings), light in weight (compared to a DCOE) and they stay in tune. Parts are available, although some GENUINE jets are getting difficult to obtain. I have found a source in Italy who can supply jets that are very well made, and having used them on carbs, work well. As well as the choke size being 'fixed, the only 'constant with regards to jets is the Emulsion-tube size---6747-6. ALL my sources say to use this size on any tuned Fiat/Abarth. They are available from the Italian gent, but a '6747-1 CAN be easily adapted. Contact me on [email protected] and I will help you out. The throttle linkage is easier to set up if you use a FZD with the linkage on the RIGHT side as you look down the carb through the trumpet.

 

[dangfiat]

Thanks all. I'll keep an eye out for another FZD (they do seem to be quite difficult to find!). Eventually I'm wanting to up the ponies a bit according to Tom's formula (650, cam, slight head work, etc).

In the meantime, it's drive it like I stole it and have a ball

 

[Toshi 975]

Thanks all. I'll keep an eye out for another FZD (they do seem to be quite difficult to find!). Eventually I'm wanting to up the ponies a bit according to Tom's formula (650, cam, slight head work, etc).

In the meantime, it's drive it like I stole it and have a ball

I have got more FZDs that are either new and or made up as complete kits along with inlets/filters and the all important mounting manifold with special studs. Used ones have been rebuilt and fitted with jets up to Abarth specification.

 

[Toshi 975]

Lot of talk on the radio about the Crown Jewels , seemed appropriate as I just had mine out for a little photographic session

 

[dangfiat]

Hey @Toshi 975

Sorry for the late(ish) reply. I had to fly out to Atlanta for a few days for a work issue (I'm a data-center engineer: have to go where the issues are!)

Mind if I DM you to discuss the "crown jewels"? I'm looking to get my 500F upto the point of a daily driver here in San Jose, California. I think I only "need" 650cc with a good head/exhaust/cam... and of course the right carbie

Considering 700cc, but avoiding the case machining (automotive machine shops here are pretty thin on the ground and we are typically a 3-4month waiting list)

Thanks in advance and hope to hear from you

Daniel

 

[the hobbler]

Hey @Toshi 975

Sorry for the late(ish) reply. I had to fly out to Atlanta for a few days for a work issue (I'm a data-center engineer: have to go where the issues are!)

Mind if I DM you to discuss the "crown jewels"? I'm looking to get my 500F upto the point of a daily driver here in San Jose, California. I think I only "need" 650cc with a good head/exhaust/cam... and of course the right carbie

Considering 700cc, but avoiding the case machining (automotive machine shops here are pretty thin on the ground and we are typically a 3-4month waiting list)

Thanks in advance and hope to hear from you

Daniel

If you are goingto change your 500 to a '652', unless you can lay your hand on a 126 engine (and then you will need to change drive-shafts, bell-housing, starter etc) you WILL need to enlarge the barrel aperture in the crankcase. As I have suggested before, rather than a CAR/TRUCK engine shop where they often have great difficulty in holding a single barrel in place (they are set-up for crankcases), try a MOTOR-BIKE shop---they are more used to machining single barrels, and might have a shorter waiting time. The 30/24 will be a good carb. Try and get one with the throttle linkage on the RIGHT side (when looking at the carb down the inlet trumpet)---it makes it much easier to set up the throttle linkage. You can use all the Fiat parts, but will most probably need an adjustable-length rod from the pivot-arm on top of the fan housing, to the carb ( the SU carb parts are perfect, along with the ball-joints for that job). I have a 32/28 on my engine and have not bothered to go through the hassle of trying to connect up the choke mechanism---being that the FZD has an accelerator-pump, a couple of pumps on the throttle works just as well!

 

[dangfiat]

Thanks for the reply @the hobbler , great info as always!

I have the 126P 650 engine already. So was thinking of just re-ringing the pistons when I rebuild. Not sure if I need to invest in new cylinders and I think the power of a hotter 650 will be OK.

Trying to see if I can "abarth on the cheap" and just go with a better head, new cam, and refresh the bearings (big ends, crank). Probably should do the oil pump & clutch while the engines out and apart

How much should I get the 650 head skimmed to increase compression to 9.5:1 or so?

Thanks
Daniel

 

[the hobbler]

Thanks for the reply @the hobbler , great info as always!

I have the 126P 650 engine already. So was thinking of just re-ringing the pistons when I rebuild. Not sure if I need to invest in new cylinders and I think the power of a hotter 650 will be OK.

Trying to see if I can "abarth on the cheap" and just go with a better head, new cam, and refresh the bearings (big ends, crank). Probably should do the oil pump & clutch while the engines out and apart

How much should I get the 650 head skimmed to increase compression to 9.5:1 or so?

Thanks
Daniel

If the head has not been skimmed before, it is normally quite safe to take 1mm (40 thou) off the head initially, then you will have to ascertain the capacityof the combustion chamber in order to work out the compression-ratio. If you contact me,I willtake a picture of what I use to ascertain combustion-chamber capacity, and a very simple formula forthen working oit the compression-ratio.
If you decide to change the oil-pump you MUST change like-for-like---don't let anybody tell you that the 500 and 126 pumps are interchangeable--THEY ARE NOT.
With regard to new rings, if the bore is within tolerances, than new rings won't hurt. Barrels can be bored +0.2mm, +0.4mm or even +0.6mm. If you needed to do rebore (and then you would only require new pistons and rings) hand the new pistons to the machine-shop PRIOR to them doing the rebore so that they are aware of what they have to rebore the barrels to in order to match the new pistons. Be very careful if you decide to give the bores a 'honing'. It is surprising how much metal is removed by a hard honing---I once went from just about acceptable to piston-slap just by giving the bores a good honing! If you
are retaining the 500 gearbox (and it is a stronger box than the 126 'box), don't forget that you will have to fit a 126 bell-housing and starter assembly. There should be no problem with retention of the starter 'pull' system.
If you think that I can be of help, always feel free to e-mail me. Have I sent you a copy of my thoughts regarding the tuning of the 126 engine?

 

[dangfiat]

Thanks for this! Yes, you've sent me your thoughts on tuning the 126.. very much appreciated. And thanks for the offer to take a pic of how you find combustion chamber cc. I'll email you directly.

I will do a compression test, but it seems I'm not burning oil. I might just replace the cam with something like a 40/80 or 35/75 (thoughts?). I assume you can pull the motor and replace the cam without removing crank & barrels?

Thanks again for the help, very much appreciated

Daniel

 

[Toshi 975]

Make contact if it was you who enquired about the FZD carb

 

[dangfiat]

Make contact if it was you who enquired about the FZD carb

Hi Toshi,

Yes, we've spoken offline and I bought one of the carbs from you. A huge thanks!

Daniel