130 TC Carb Mounts / Baseplate / Carbs/ Airbox

[Abarthnorway - Remi L]

Hi All!

Seems everyone wants new flexible carb mounts for their 130 tc engines... Also hear a lot of talk about them breaking/leaking etc. There are two reasons these mounts break/leak.

1. Age
2. Improper use

I have seen countless examples of the latter.
The 130 TC comes originally with a baseplate that fix onto, and support the pair of carbs (front end of carbs). This keeps the carbs from individual flexing, and this plate is again a part of the Abarth airbox. From this plate there is a stabiliser bar going down to a bracket on the block - fixed with a rubber bush....

This stabiliser bar/bush helps support the weight of the carbs and airbox, and also contribute to reduce carb vibrations together with the flexible carb mounts. Without this flexibility, fuel will frothe in carbs and seriously upset jetting!!

Make sure this stabiliser bar is in place, in good condition and connected correctly. There are many reasons why the stabilisor bar/baseplate is missing. Removing airbox for "Tuning" with socks or airfilters (that draw hot air from radiator right through carbs..), or "missing" after carb or engine service seems to be the usual explanation.

The weight of carbs/airbox, and vibrations of the engine will break the flexible mounts within a very short time without baseplate and stabilisor bar. Guaranteed! Correctly fitted the mounts will last for many years.

Btw GC sells alu. carb mounts that fixes problem once and for all, and will also be fit for 45 mm conversion.

Regarding the baseplate there is two different types. One is has Solex written/stamped on it, the other is for Weber and has to my knowledge nothing written on it.

The only difference between the two is that the Solex have four holes for carb mouth of 45 mm, while the Weber type is only 40mm. Reason is that the Solex C40 Addhe tipo 37 (Haynes workkshop manual states tipo 27 - Wrong!! - which is a rather different carb.) actually has a carb bore of 45 mm all the way to the venturi choke, only the throttle plate is 40 mm.....
Source a Solex baseplate for 45 mm carb conversion

My personal favourite regarding Weber/Solex is the Solex because of its more delicate internals(aux.venturi) and 45 mm bore mouth. Seems to give a bit more grunt......

Easy - and not backed by hard data!! - way to get a bit better grunt in engines fitted with Solexes, is to change the chokes to 34 mm size Then ream the main jets to 150/155 (std engine/flowed head). I have tried both and I can assure one thing. The engine pulls about 200-300 rpms further and top speed increases a bit..... :!:, without loosing the bottom end torque.

On tuned 130 tc engines there is also a problem with fuel delivery at full throttle with original pump. Reason is the fuel return line. For tuned engines this will need to be blocked or at least clamped slightly or you will risk ruining your engine at high revs.... be careful

And by all means keep the original Airbox - it keeps cold air flowing into the engine. and most important - it has ABARTH written all over it :!:

Good luck

Remi Lovhoiden

[Guy Croft]

What an excellent technical feature Remi!

Well done! And such a marvellous grasp of English. Keep going like that and you can take over my website job!

The only thing I would add - if you can spare the time - is a few photos, there are those members of course - not yet converted to the joys of Fiat Twin-Cam Heritage tuning - who will not have much idea what this all looks like.

Sincerely,

GC

[Piero]

Hi Remi,
As Guy said, good work.
I am in the middle of a 131 engine tune,
I will be using the very same set up as you have just spoken about,
I have a question you might be able to anwser for me please.
The straight shot inlet manifold used on the 130 Abarth, seems to mis-match my cyl head, it looks like it needs a gasket of about 3mm before the ports all line up.
It is standard, and never has been opend out (inc head)
Any ideas
Piero

[Abarthnorway - Remi L]

Hi Piero!

I suppose the mismatch between manifold & head you refer to is caused by the manifold having a slightly smaller bore than the head at the contact faces....?... and therefore there will be a bit of a downstream mismatch.

So is also the case on the 130. I think all TCs have the same port opening.

With the standard inlet manifold gasket the manifold has a downstream mismatch especially at the bottom of the port... and slightly on the port sides at cyl 1 and 4. The effect of this is not significant as long as the inlet ports have not been opened up a lot.... Flowbench results is posted by GC at
viewtopic.php?t=7

If you still feel the need to fix the mismatch, you can match both head and manifold to the inlet manifold gasket. This can be done with a cheap Dremel tool but is a bit time consuming... or buy a more serious tool with appropriate carbide burrs... will cost some money though. I doubt that using double gaskets or similar will help flow... but the mismatch will seem smaller.

Smoothing ports and short side radius, and correctly opened up multi angle valve seats are much more important to flow - but a nicely matched manifold and head just looks gorgeous :!:

By the way - where are you planning to put the distributor and brake cylinder?
To my memory the block mounted 131 unit will foul the 130 tc manifold...and the 130 tc distributor will hit the firewall(? correct english)... and the 131 brake cylinder is where the carbs should be....

Btw - I will see if I can post some pictures of 130 TC setup in the future. Only problem is that car is in Norway and I am in Switzerland.

Good luck to You

Remi Lovhoiden

[Piero]

Hi,
First of, my engine will not be fitted to a Fiat, so I have no issues with distributor etc, will ex cam box mount it anyway.
The mis-match that I speak of, is simply taken away by a 2-3mm gasket.
the port sizes are the same.
Looks to me as Fiat forgot the head face is at an angle, so the closer the manifold gets to the head face, the worse it is (past this 3mm out point)
My manifold and head, are genuine 130 un-toched items, never having been opened out.
will try and post some quality photos of what I mean.
Piero

[Guy Croft]

I wrote about mismatches in GC V/W.

If you find the ports on the 130TC manifold are a bit smaller than the head, does this matter?

The answer depends on the flow characteristic of the manifold and its entry profile - the latter meaning does the air exit the manifold in a direction that suits the main port flow of the head, and the flow potential of the manifold itself.

In the case of the 130TC manifold the answer is, no, it doesn't matter. The exit flow goes exactly the right way, and the upstream mismatch doesn't matter at all, not functionally anyhow. The 130TC manifold (well, the inner alloy part that I just flow tested for this thread, sorry, left camera at home) flows c 126 cfm, more than you are likely to get from your head with 43.5mm inlet valves in any spec.

GC

[Abarthnorway - Remi L]

Fianlly 5 years later some pics of the 130 TC setup:

Airbox components - Filter - Lid - Mesh under filter to hold it in place - Airbox itself - Backplate

Airbox components.jpg (59.23 KiB) Viewed 25097 times

Assembeled airbox seen from front of car

Front.jpg (60.74 KiB) Viewed 25097 times

From the carb end - the baseplates are either 40mm (for Weber) or 45 with stamped SOLEX....

Backside.jpg (56.04 KiB) Viewed 25097 times

The stabilizor bar going from a bracket on the block to the bottom of the baseplate - saves the carb rubber gaskets. Pics from engine in use.....

Supporting bracket.jpg (46.91 KiB) Viewed 25097 times

Here is the setup from the manifold side. Stabilizor plate between the two carbs adds stability.

Manifold, baseplate and ONE rubber gasket.jpg (74.15 KiB) Viewed 25097 times

Mounted

Correct way of mounting.jpg (65.4 KiB) Viewed 25097 times

Remi Lovhoiden

[Abarthnorway - Remi L]

Hi!


Originally the 130 TC came fitted with either Solex C40 ADDHE or Weber 40 DCOE - both fitted with 32 venturies.
I will be trying to compare the two original fitted carbs as the air sees it from the airbox side in combination with a 36 choke to visualize the differences:


Comparison Weber vs Solex:


Air horns:

Red plastic RamPipe is Solex - Steel one Weber

DSC_2640.jpg (111.65 KiB) Viewed 25089 times

From backside

DSC_2647.jpg (153.07 KiB) Viewed 25089 times

Radius into the rampipe seen from the airbox end compared. A generous radius minimizes entry losses I have read somewhere......

DSC_2643.jpg (126.8 KiB) Viewed 25089 times

This is the end of the rampipe as it enters the carb - see the difference in size!!

DSC_2650.jpg (130.95 KiB) Viewed 25089 times

Here we can clearly see that the Solex ram pipe has a much bigger size as it enters the carb - actually 45 mm vs the Webers 40 mm. Lets dive in further:

Auxilary venturi:

Weber left - Solex right

DSC_2646.jpg (125.29 KiB) Viewed 25089 times

The diameter of the Weber aux. venturi is actually tapering down to 37.5 mm at the smallest, while the Solex keeps 45 mm all the way. The arms holding the aux.venturi in the Weber is more bulky in size. For information - In Dellorto DHLA the supporting arm is omitted altogether.


Next step chokesize and vakuum signal needed for correct fuel delivery:

36 mm considered a good choice for fast road and mild tuning

DSC_2649.jpg (103.48 KiB) Viewed 25089 times

In weber

As seen in Weber

DSC_2651.jpg (127.99 KiB) Viewed 25089 times

This is what it looks like in the Weber - I mean if You can see it at all. The difference between aux. venturi and choke diameter is only 0.75 each side - not a good vakuum signal!! No surprise 34 mm is considered the biggest effective size in a Weber 40....



In a Solex

As seen in Solex

DSC_2652.jpg (127.77 KiB) Viewed 25089 times

Here You can see the 36 mm choke with the Solex. Now You can see the "wing" shape of the venturi clearly - the differece in size is 4.5 mm each side.


The conclusion for me is that if You want to stick with standard Carbs on the 130 TC the Weber and Solex come out about the same when using 32 mm chokes - here the Weber might even have an advantage as 32 mm choke is too small for a 45 body - the step it creates will be less intrusive in the 37.5mm weber.....BUT for any tuning utilizing bigger venturies/chokes the choice definately must be the Solex. No wonder the biggest recommenden choke for Weber is 34 mm.....

I have always had a fascination for the Solex - I consider it better suited for used on a tuned engine. That most people consider Solex inferior to the Weber is just a bonus:-) The challenge with Solex is to source jets and spare parts - but parts can still be found.

For the curious I can say that the Abarth Solex is not similar to standard Solex ADDHE. It has different emulsion tubes (AO4), with specially designed main jets and air jets. The carb size is 45 mm all the way to the choke, and it was called "competizione" or something in Italy. The throttle plate is of course 40 mm - but the body can be machined out around the throttle to make it a true 45 mm carb by fitting new plates and spindle - I have seen them.

The Weber carb is also a "special" for the Abarth with different aux venturi size (60 vs 45 for normal)



Best regards

Remi Lovhoiden

[Abarthnorway - Remi L]

Hi All!


I will continue my comparison between the Weber 40 DCOE 146 - Tipo 50 VS Solex C40 Addhe 37.

The Solex always get a beating when talking about the 130 TC, and I cannot understand why, as I consider them the best application this car - especially tuned versions as I consider them more adjustable in most ways.

Here we go:

Weber float bowl.jpg (134.86 KiB) Viewed 24922 times

Float bowl of the Weber: Visible jets are air corrector jets with emulsion tubes and main jets underneath. Just under the jets You find the holes that hold the idle jet. In the small square between these You will see two small drilled holes - thats the air correction for the idle circuit.... no adjustments possible in that curcuit without extensive work.

Solexfloatbowl.jpg (11.41 KiB) Viewed 24922 times

Solex float bowl: Here You find the brass idle jets on top sides of the "cluster". In between these you find some smaller jets (4mm) that are the air correctors for this circuit. They are removable and can easily changed. In the top corners of the picture You will see some small "silvercoloured screws" - they are idle bypass jets. These let you adjust each of the two barrels separately - in my memory You wont find this function in the Webers.

Weber Solex body.jpg (154.21 KiB) Viewed 24922 times

Her You see the stripped bodies side by side. The "fat one" is Weber, and the "petite" is Solex. Weight difference is considerable...

Solex throttle shaft.jpg (122.98 KiB) Viewed 24922 times

The throttle shaft of the solex is 8mm diameter all the way, and considering the 40mm bore they protrude quite a bit....... The throttle plate screws are not very visible when fitted as the holes are sunk into the shafts - thats good. This picture busts a myth regarding the throttle shafts of the Solex causing damage to the body due to bad or nonexisting bearings. The bearings are fitted with small gaskets everywhere, and are very tough. They fit into the carb body with a tight fit. When refitting its a good idea to hone and chamfer their housings, and also heat the body slightly to ease the process - and avoid knocking the carb to pieces.

Weber throttle shaft.jpg (155.15 KiB) Viewed 24922 times

The weber throttle shaft is slimmed down in the barrels of the carbs to 6mm - only advantage of the Weber so far in my opinion. The throttle plate screws are bulky and square.

Solex progression.jpg (139.76 KiB) Viewed 24922 times

Solex progression drillings 5 holes - these carbs stumble a bit more than Webers when cruising, probably due to lean jetting in the transition between idle/main circuit. Suppose it will be possible to "iron out" with smaller air correctors on the idle circuit.

Weber progression.jpg (129.52 KiB) Viewed 24922 times

Weber progression drillings - 5


Shame about the big throttle shaft though.....

Throttleshaft Solex modified.jpg (94.81 KiB) Viewed 24922 times

Now 5 mm in the barrels - and the throttleplate screws will not be visible at all...


All in all these are both very good carbs, but I consider the solexes better suited for tuning and adjustability. Its a real pity jets and spare parts are VERY hard to find these days, thats their main drawback. There are several more differences not shown here, but they do not affect their operation and for this comparison not interesting.


Best regards

Remi Lovhoiden

[Urbancamo]

Remi;

This is absolutely brilliant thread. For me, this thread has removed mystery net over these carbs.

There's couple reasons why you don't see these very much.

- Their adabtability on different applications is very limited compared to Dellortos/Webers (because they are mainly OEM specific carburettors)
- Spare part, jet etc. policy is not even the same dimension compared to two main brands...
- Solex has pretty bad reputation, if you ask people, they automatically say they are junk (even they are just working carburettors)

T

[Abarthnorway - Remi L]

Remi;

This is absolutely brilliant thread. For me, this thread has removed mystery net over these carbs.

There's couple reasons why you don't see these very much.

- Their adabtability on different applications is very limited compared to Dellortos/Webers (because they are mainly OEM specific carburettors)
- Spare part, jet etc. policy is not even the same dimension compared to two main brands...
- Solex has pretty bad reputation, if you ask people, they automatically say they are junk (even they are just working carburettors)

T

Hi Tommi!

Thanks for appreciating the article!! Good to have someone else around this forum that enjoy and understand carbs.

Their adaptability is absolutely brilliant not standing behind Dellorto or Webers in ANY way - this is not the normal Addhe.....The normal often model specific addhe`s have smaller bore up until the venturi choke, fixed air correctors (brass sleeves), and use another type of aircorrectors, emulsion tubes and main jets. The 37 (As fitted to Abarths) version are fully adjustable.
As You say - the main challenge is sourcing jets.
I am working on that:-)

I cannot speak for all Solexes - but regarding this version I just cannot understand the neverending bashing they constantly suffer - the critics never seem to mention the lack of jets, but critizise the operation and inferior performance and reliability of Solex compared to Weber..... Thats the actual motivation for writing this article.


Remi

45ADDHE1.gif (54.7 KiB) Viewed 24907 times

[mitch strada]

Excellent write up thanks for taking the time to do it - i enjoyed reading it and learned from it too.

[Guy Croft]

MODEL POST!

Very well illustrated and captioned - excellent work Remi!

The only thing I don't about the Solex carbs is the bottom-mounted diaphram for the pump jets. In common with DHLA.

That and also that any set I see for sale is (politely..) 'well-overdue for' (or utterly beyond) overhaul!

GC

[TomLouwrier]

hi Remi,

This is an interesting and well written / illustrated thread, I'm enjoying it a lot.

My personal experience with Solexes is limited to much simpler, single choke or dual-progressive choke types. I've usually found that they have a tendency to wear out the spindles (the carbs shown here have nice bearing, so that won't be a problem) due to materials chosen and the way the forces from the cable and the acceleration pump work. Also the most common system they use for depressing the membrane leads to quick wear in the pump lever.

That said, I'm very interested in seeing the back to back results of these two competitors on a flow bench. After all: it's the flow that matters.

regards
Tom.

[Abarthnorway - Remi L]

Hi Tom!

Ragarding the flow I suppose the choke size will determine a lot, but the Solex is more "delicate" in the barrels - except a massive 8mm throttle shaf. No idea really as I do not have a flowbench. Better ask the "boss".......

When using bigger chokes I suppose the vakuumsignal will be better in the Solex, as it has bigger dimensions everywhere except throttle plate size. That was actually another important criteria, as it will be used for racing purposes with a GC 130 tc head.

Remi