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Tuning SOLEX 32PHH and 35PHH Carburettors

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Tuning SOLEX 32PHH and 35PHH Carburettors

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Toshi 975

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Does anyone have experience of these particular carbs. They were originally fitted in pairs to the Lancia Fulvia or as a single twin choke carb on the Fiat 1100R. They seem to be well recognised in Italy as a good tuning carb for the air cooled engines. I only recently discovered that the 32PHH ever existed and managed to find a complete but slightly sad one on ebay which I believe is from a Fiat 1100R so will be jetted accordingly. I guess that in theory one carb from a 1300 Lancia would be jetted for 650cc :) so interested in jet sizes if anyone has a note of these.
 

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Toshi 975 said:
Does anyone have experience of these particular carbs. They were originally fitted in pairs to the Lancia Fulvia or as a single twin choke carb on the Fiat 1100R. They seem to be well recognised in Italy as a good tuning carb for the air cooled engines. I only recently discovered that the 32PHH ever existed and managed to find a complete but slightly sad one on ebay which I believe is from a Fiat 1100R so will be jetted accordingly. I guess that in theory one carb from a 1300 Lancia would be jetted for 650cc :) so interested in jet sizes if anyone has a note of these.
Click to expand...

Hi Dave, I have been looking into these carbs for a while now (specifically the C35phh) having obtained a NOS item from Sicily with manifold for the Panda head. I have notes of the Fulvia applications jetting, plus a few others, but there is a list of six different applications for the Fulvia C35phh alone all with differing jetting!!! I'll have a dig around and let you know.
Dave, can you identify the model of C32phh you have??? (stamped in the circular markings above the manifold face) and the size of the fixed choke, It would help me. thanks.

Ian.
 
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Hi Dave, I have had a good look at your picture and as far as I can tell it seems that you have the number 1 of a pair. going by the type of disc starter you have and the position of the linkage and the fuel pipe you may have the forward carb of a pair. looking from the front of the car the carbs would be mounted on the left. I cannot be certain without better pics - unless the seller can confirm the provenance ????
Ian.
 
The web-site "Fulvias in France: Fulvia thoughts-6" has a number of tuning options on the 1300 and 1600 Fulvias with regard to the jetting of the PHH Solex carbs. Being that 2 of these carbs were used on the Fulvia, yes, you are correct--being that 1/2 of 1300 is 650, the jetting won't be too far out; definately close enough that you will be able to start the car, and sensibly run it to a rolling-road for final setting up.
 
Bleeding Knuckles said:
Hi Dave, I have been looking into these carbs for a while now
Dave, can you identify the model of C32phh you have??? (stamped in the circular markings above the manifold face) and the size of the fixed choke, It would help me. thanks.

Ian.
Click to expand...

Had a look at the carb and it is a Solex C32PHH / 6 and they were used on some of the Fiat 124 models. I have a 124 manual and the jet sizes all match which is probably the worst set up from my point of view being a single carb on a 1500cc engine. So looks like I will need to replace all jets to have a chance of using it.
 
Toshi 975 said:
Had a look at the carb and it is a Solex C32PHH / 6 and they were used on some of the Fiat 124 models. I have a 124 manual and the jet sizes all match which is probably the worst set up from my point of view being a single carb on a 1500cc engine. So looks like I will need to replace all jets to have a chance of using it.
Click to expand...

Hi Dave, If you need a supply of jets let me know as I have a few notes of people who can get them to you.

Ian.
 
Toshi 975 said:
Had a look at the carb and it is a Solex C32PHH / 6 and they were used on some of the Fiat 124 models. I have a 124 manual and the jet sizes all match which is probably the worst set up from my point of view being a single carb on a 1500cc engine. So looks like I will need to replace all jets to have a chance of using it.
Click to expand...

Yes, this carb was used on the early 124 model (which was 1197cc not 1500) and was then replaced by a twin choke downdraft carb with vacuum operated secondary choke - for good reason. The early side draft carbed cars didn't run very smoothly.


I wouldn't have thought this carb would be good to use on a Fiat 500/650.

The main problem I'd forsee is air speed through the carb dropping too low when the 2 x 32mm chokes are opened. You can go as small as you like with the jets but you can do little about the air speed apart from maybe changing the venturi sizes. Air speed is what causes the depression that draws fuel through the jets, atomises it and transports it into the cylinders.


A better choice of carb might be what Fiat did with the later 124's i.e. fit a twin choke carb with the second choke only opening when there was sufficient vacuum or use a carb which delays the opening of the second choke by mechanical linkage means.


I've always believed an S.U. carb of approx. 1-1/4 inch ( maybe 1-1/2") bore would be a good choice for a tuned 500/650 cc engine. Only one needle to change, no jet changes, acceleration enrichment mainly by way of an oil damper on the piston, effective choke size can't be too big for the engine as the piston only rises if there is sufficient vacuum (depression). Of course there's 100's of needles to choose from. I did see a guide to selecting the correct needle on the i/net a while back but I can't find a link.


That's what I did with an early 124 I had. With a 1-1/2" S.U. fitted, it ran great, no flat spots, no surging, better economy, no flooding. :)

AL.
 
As far as I can see, the best of the SU range to fit onto the 500/126 engine would be the HS2---1-1/4in (31.75mm) semi-downdraught. The version to fit is one that has the float-chamber on the left side of the carb, looking from the air-filter end: i.e as the air would flow in. The HS2 has the same fitment angle and flange measurements as the FZD, so a standard FZD inlet manifold can be used. The FZD was often used as a 'tune-up replacement' on the mini range of cars. Burlen Fuels (the current owners and manufacturers of the whole SU range) have no info on fitting the SU to a 500/126 engine, but suggested to me to start with the same settings as used on the MC2 (although some info says H2) (1-1/4in side-draught) carb that was fitted to the Police 650cc Triumph Thunderbird motorbikes. I was able to sneak a look at a 'Thunderbird' owner's handbook (at an auto-jumble) and the jet was a AUD 8142 (90th-pink), the needle a M9/EP (although the Thunderbird handbook suggested a M7 if a 'chair'was fitted---more load, so slightly richer) with a red spring (AUC 4387). Whilst these settings would be fairly close to correct, they would require checking/altering on a rolling road.
 
There even used to be an inch and 1/8th S.U.. Iirc it was fitted to e.g. the 803?cc Morris minor. (not much larger than a Fiat 500/650 engine)

www.winsu.co.uk S.U. Needle selection program + tuning software

www.sucarb.co.uk On home page, enter vehicle make and model in box and see details of SU carb fitted, incl. needle used etc. This site is part of Burlen Fuel Services (owner of the SU name). If you enter Triumph Motorcycle it gives details of the carb used and settings.

www.holdenpaedia-oldholden.com/SU_Carburettors This site includes carb sizes and designations (tag attached to float bowl screw), also a very interesting animation of how the SU carb works - this is worth watching by anyone who wants to see how an SU carb works and how simple it is.

The SU carb jet stays the same for each size of carb and will be 0.09" or 0.10" or 0.125" e.g. all 1-1/4 inch SU carbs use a 0.09" jet - its the needle which is chosen to suit the engine (there's 100's of different profiles of needles).

The piston spring (fitted above the piston inside the dashpot) - there's only a maximum of 4 variations for each size of carb. They're colour coded.

Before the availability of 'rolling-road' tuning, there was a system of needle selection using a certain kind of roadtest. This is described here:-
www.tecb.eu/onewebmedia/Tuning_SU_Carbs.pdf is a website that shows a reprint of a book on tuning the SU carb, originally published by Cars and Car Conversions Magazine/SpeedSport motorbooks. On page 31, there is a list of SU carb specs by car make/model, type of carb fitted, rich/std/weak needle options and colour of spring fitted. Page 38 gives an index of 0.09" jet needles listing the step sizes of each needle letter code.

Also,if you switch to an SU carb, you can forget about your idle jet becoming blocked.....

Did I mention that I was a fan of the SU carb? :)

AL.
 
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F123C said:
The main problem I'd forsee is air speed through the carb dropping too low when the 2 x 32mm chokes are opened. You can go as small as you like with the jets but you can do little about the air speed apart from maybe changing the venturi sizes. Air speed is what causes the depression that draws fuel through the jets, atomises it and transports it into the cylinders.
AL.
Click to expand...

Hi Al, I note your last comments and agree that with a small capacity engine the air mass flow through the carb may not be sufficient for good running, however, I have a C35phh that has fixed 31mm venturis - they do come with smaller 29mm venturis and I believe that the C32phh will be similar. I found a chart that gives choke diameter selection dependant on a single cylinder capacity and the rpm proposed.
So with my engine of 712cc and running at 6000rpm I get a choke diameter of 30.5mm and running at 6500rpm I get a choke diameter of 31.7mm (y)(y)(y)
I intend to fit my C35phh jetted for a Peugeot 104 ZS 2
the engine was 1361cc ran 10.2:1 CR put out some 93bhp at 5800rpm (y)(y)(y)
The Peugeot ran two Solex C35phh 9 carbs so I should be in the ball park - I hope!!!!!
Ian.
 
Bleeding Knuckles said:
Hi Dave, If you need a supply of jets let me know as I have a few notes of people who can get them to you.

Ian.
Click to expand...

Very good of you Ian ? Not really at that stage yet as I only have one jetting list for the Lancia Fulvia Solex 32PHH and will also need a full service kit. Then my bargain ebay purchase has issues mainly that the butterflies are still seized so need some careful work. Then there is the issue of a suitable manifold but I am not in a hurry with this and am enjoying all the input here. According to the 124 manual the Venturi size is 23mm so it is in the same league as the later Weber 30DIC carbs which has progressive chokes rather than the simultaneous Solex. It was the smaller size of the 32PHH that drew my interest as I thought that it might be more "friendly" on a tuned 650cc.
 
the web-site "500 mania" sells both the inlet manifold for fitting a PHH to a 500or 126 head and the supporting bracket. For jetting, look on the site I suggested---"Fulvias in France: Fulvia thoughts-6" There will be plenty of information on that site to help you sort out the required jets.
 
F123C;4365291 Did I mention that I was a fan of the SU carb? :) AL.[/QUOTE said:
I am also a fan of the SU carb and I would guess that I have driven cars fitted with SU carbs the best part of a quarter of a million miles in my motoring life. Morris Minors, Mk1 Sprite with the 1 1/8" carbs, Mk3 Sprite that I clocked up 101,000 miles in and I even converted a Morris Minor carb to a downdraft SU and fitted it to my old 1947 Sunbeam Talbot. It worked much better than the original leaky old Zenith 30VIG ?
For some reason I just do not think that the SU looks right on a Fiat.
Click to expand...
 
Toshi 975 said:
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For some reason I just do not think that the SU looks right on a Fiat.
Click to expand...

Some might say it doesn't look right on a Harley-Davidson either but it works great.

And, you can polish the dashpot until it looks like chrome (or fit a cover). :D

Every time I read of someone on here having carb issues on their 500, particularly a blocked idle jet, I can't help but think of fitting an SU carb.
(No idle jet = no possibility of blockage). Difficult to cause a fuel blockage in an SU carb (not impossible though :) ).

AL.
 
Dave, I don't suppose you've considered fitting a twin-choke (downdraft) carb from a Fiat 850 Coupe (843/903cc) suitably (slightly) rejetted?

But, nowadays, I suppose the problem would be where to get such a carb to experiment with....

(Memo to self:- must have a rummage in my shed to see what I've kept...
apart from the SU's, of course :D ).

AL.
 
But does a SU carb look any more out of place on a 500 than a motor-bike carb? (Mikuni or Keihin)---and these are being used in Italy, 500 Mania sells the manifolds for them. A modern, still-being-made-by-Dellorto carb that is also being used in Italy (again, manifold available from 500 Mania) is the Dellorto 'OVC 34/30D'. These were/are fitted to the Piaggio Ape "Poker" and are in reality a side-draught version of the FZD. The 'D' version has to be used as it the version with an accelerator pump; some versions (the 34/30A for example) do not have an accelerator pump being that they are used on outboard engines.
 
the hobbler said:
the web-site "500 mania" sells both the inlet manifold for fitting a PHH to a 500or 126 head and the supporting bracket. For jetting, look on the site I suggested---"Fulvias in France: Fulvia thoughts-6" There will be plenty of information on that site to help you sort out the required jets.
Click to expand...

I looked at the jetting details and they all referred to set ups for the C35PHH rather than the C32PHH but made some good reading with some interesting points.
 
Toshi 975 said:
. According to the 124 manual the Venturi size is 23mm so it is in the same league as the later Weber 30DIC carbs which has progressive chokes rather than the simultaneous Solex. It was the smaller size of the 32PHH that drew my interest as I thought that it might be more "friendly" on a tuned 650cc.
Click to expand...

Hi Dave, No problem with the jetting - when you are ready. My weber 30 DGF from a Panda 30 has two 23mm chokes and performs well, I went up one stage on all jets to assist with cooling during the running in and it still runs well in all conditions, the only other part I changed was the 'wonky' panda manifold for a low level part from 500 Mania, it fits well. I did think that having the Panda head and manifold ported and polished would mess up the running, but no, it still goes well.
But, there is nothing like the noise of a twin choke sucking the atmosphere out of your ears - yes!!! :eek::eek:

Ian.
 
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