As I am in the middle of restoring my 1969 500L, I am, like many, looking at my engine options. I am trying to locate a 126 engine and transmission, which as you can imagine is difficult here in the USA. Probably going to build a 700cc engine similar to what Chris did.

As far as carburetors go I have read quite a bit. The FZD is just too ridiculous in cost. The 28 IMB is maybe a possibility but maybe a bit small and has no accelerator pump.

What about the Solex 34PBIC? This is the carburetor that Abarth originally installed on the 695SS. They seem to be much lower in cost, and are available used and new. There is an available Abarth combination valve cover / manifold single casting specifically for these carbs from most of the suppliers.

Does anyone have any experience with this carburetor? All comments welcome.

John

John,

What cylinder head were you thinking of using? The standard 126 head or a Panda 30? With the Panda head you then have the options of Weber and Dell'Orto side draft carbs, which are used on many 695 engines.

Cheers,
Matt

Thanks Matt,

I intend to use a 126 head massaged along the lines that Chris did (35mm intake and cleaned up ports, etc.). I can say I have no interest in going to anything other than using a mildly modified stock head.
If you think 126 bits are scarce in the USA, Panda parts would be unobtanium! I have some friends in the USA Fiat club looking for me. www.fiatclubamerica.com

Want to make a 600 - 700cc engine that makes 30+hp. More interested in torque than high rpm horsepower. The car will be used for driving around town and maybe on some trips. Looking for faster acceleration and overall better drivability in modern traffic.

John

Hi John,

From my information the original Abarth 595SS and 695SS were both fitted with the 34PBIC. Both of these engines were in a high state of tune with 10.5:1 and 9.8:1 compression ratios respectively. The milder Abarth 695 was equipped with a 28PB and ran an 8.5:1 CR.

The 34PBIC was also used on Citroens and Renaults so you are right - they should be cheaper and there should still be plenty around, possibly even new old stock, though I have no idea what jetting you would use for your engine.

The FZD was never stock mounted on any engine and was always sold as an after market bolt-on. They are rare and expensive but they are very good.

Alternatives would be Webers - eg: 30DIC, 30DGV, 30DGS etc - or even SUs.

See here for a brief discussion of the Webers -

https://www.fiatforum.com/500-classic/301381-new-again-forum-3.html

and here for the SU -

https://www.fiatforum.com/500-classic/304606-650-carburetor-upgrade.html

Chris

Thanks Chris, excellent information as always!

My Abarth book (Abarth, by Pat Braden and Greg Schmidt) shows the 595SS and 695SS with the Solex 34PBIC and the non-SS 595 version with the Solex 28PBJ.

Just trying to find an economical carburetor set up that will work well with a 600-700cc engine that has been massaged similar to your engine. Maybe even an American one barrel Autolite!

I will check out the Webers and Solexs. I am not a real fan of the SU carbs with the constant depression moving mixture needles and the little oil reservoirs that must be kept filled. I had those on a 1966 Sunbeam Alpine (duals) and was not impressed.

Problem in the USA is any engine upgrade is difficult. You can of course have a used engine shipped from Europe, but that is expensive.

Best regards,

John

Oops - forgot about the 'standard' 595. Yep - you are right, it used a Solex C28PBJ (whatever that is ??) and ran a 9.2:1 CR for 27bhp @ 5000rpm.

One of my reference books is Greggio's 'Abarth, the man, the machines' published by Giorgio Nada. It's quite a large book, full of fascinating information and it covers all of the Abarths - Fiat, Simca, Porsche derived etc.

I've attached a couple of photos from that book. The conversion kit is similar to what I've done with my engine so I'm quite happy to believe that my rebuild is faithful to what could have been achieved at the time.

Regards,
Chris

Hi John, for what it's worth I was considering the 34 pbic also or the weber 30 dic. I has also discounted the the dellorto fzd on cost although from what I read it appeared to be the best carb for this engine. I consulted Middle Barton Garage in England for their opinion and was advised against the 34 pbic in favour of the 30 dic on the grounds that the solex was old fashioned and harder to find parts for with the remanufactured versions being of poorer quality than the originals. I have a 650 engine with gas flowed head, aftermarket cam and exhaust and electronic ignition. It is near completion and I will post once it is running to report on it.
One aspect interested me in upgrading the carburetor an d that was the air supply. I had always believed that a source of cooler air being fed to the carburetor from outside improved the running and power output instead of the carburetor having to suck hot air in from the engine bay, as per the original setup where the cool air if filtered through to the carburetor. The advantage of the weber 30 dic (and solex 34 pbic) is that there are air covers for the top of the carburetors that allow this original system with air filter cannister to be used. They guy building my engine builds race engines and maintains that the temperature of the air makes a noticable difference to the torque the engine can produce. Keep us posted on your project.

Colm.

Thanks Colm,

That is good information on the 34PBIC. What carburetor are you going to use?

Cooler air = denser air = higher output.

John

Many years ago I fitted a 500 with Giannini tuning bits plus a Solex Type B32 PBI-5, as used, in pairs, on the 2.4 litre Jaguar. Definitely made a difference. Then I went the whole hog and fitted a flat twin BMW engine of 700cc, as used in the BMW 700 Coupé, fitted with motor-cyle-type Amal carburettors - a lovely piece of engineering, with many roller and ball bearings, and an enormous appetite for high revs - it also lowered the centre of gravity very significantly and the result used to leave Mini Coopers standing.

Hi John;
Shame you are so anti SU carburettors because the HS2 is a perfect match for the 595/650/695 variants of the 500 engine. HS2 means that it is a 1-1/4 inch, semi downdraught. The version to use is the left-hand, variable-angle float; Using the appropriate float chamber/carb body adaptor, the float chamber can be made to sit at 20 degrees to the horizontal, the same angle as the Dellorto FZD, and the carb-to-manifold flange on the FZD inlet manifold exactly matches the HS2 SU flange--even the bolt spacings are the same. 1-1/4 inches is 32mm, the same venturi size as the FZD--and a darn site more available and cheaper. By using the left hand version, the throttle linkage can be at the rear of the car, easily accessible. I am going to look seriously at this combination on my 695 project--when I know which piston spring and needle to use, I will advise the forum--hope this helps

the hobbler said:

Hi John;
Shame you are so anti SU carburettors because the HS2 is a perfect match for the 595/650/695 variants of the 500 engine. HS2 means that it is a 1-1/4 inch, semi downdraught. The version to use is the left-hand, variable-angle float; Using the appropriate float chamber/carb body adaptor, the float chamber can be made to sit at 20 degrees to the horizontal, the same angle as the Dellorto FZD, and the carb-to-manifold flange on the FZD inlet manifold exactly matches the HS2 SU flange--even the bolt spacings are the same. 1-1/4 inches is 32mm, the same venturi size as the FZD--and a darn site more available and cheaper. By using the left hand version, the throttle linkage can be at the rear of the car, easily accessible. I am going to look seriously at this combination on my 695 project--when I know which piston spring and needle to use, I will advise the forum--hope this helps

Click to expand...

There's just something very non-Italian about an SU, don't you think?

Hi John, I'm using a weber 30dic carburetor bought off Matt here on this forum.
It is on the car but still has to be set up, just waiting for a few linkages etc.
If you check the "New (again) to forum" thread a couple of pages back, it came off that yellow car from Belgium. An alternative and similar carburetor is the Weber 30 DGF from the 650 twin port Panda 30 engine.

Cheers,

Colm.

the hobbler said:

Hi John;
Shame you are so anti SU carburettors because the HS2 is a perfect match for the 595/650/695 variants of the 500 engine. HS2 means that it is a 1-1/4 inch, semi downdraught. The version to use is the left-hand, variable-angle float; Using the appropriate float chamber/carb body adaptor, the float chamber can be made to sit at 20 degrees to the horizontal, the same angle as the Dellorto FZD, and the carb-to-manifold flange on the FZD inlet manifold exactly matches the HS2 SU flange--even the bolt spacings are the same. 1-1/4 inches is 32mm, the same venturi size as the FZD--and a darn site more available and cheaper. By using the left hand version, the throttle linkage can be at the rear of the car, easily accessible. I am going to look seriously at this combination on my 695 project--when I know which piston spring and needle to use, I will advise the forum--hope this helps

Click to expand...

Wow, thank you for the very detailed information. I will wait and see how this set up works for you. I am not anti SU, they are just not my favorite way to go. I have always considered them a bit "fiddly", requiring occasional adjustment where say a weber is more stable once sorted out. Let us know how it works out and especially what it ended up costing. SU's are readily available in the USA as this is where most of the UK auto output in the 60's and 70's ended up.
John

Hobbler,

So the Zenith Stromberg comparable carb to the HS2 would be the CD 125?

John

How difficult is it to fit a BMW flat twin. The Austrian Steyer puch version of the 500 used a flat twin and it reved better.
Is there any benefit of fitting an electric fan and removing the belt driven one?