Diploma work - GTT carb

[Jimmy_GTT]

I'm attending a 'Classic car restoration' course in a university and now it is time for the diploma work. It will be: Renault 5 GT Turbo carb. restoration
I'd like to collect all the info about the carb. I know the articles session here and already spent several hours searching the topics about problems with the carb but there are many where the solution is not written.
So if you have any story of your carb please write it here because it could be very usefull for me.
Thanks

[Trevhib]

Might be a good idea to state specifically what info you already have to save anyone wasting their time Jimmy. :agree:

Maybe you could see this as a chance to help the club by collating all the info you gather for your diploma work and posting it in this thread?

[Phoenix Autosport]

it would be well worth your while signing up to the forum on
www.xrtwo.com
its a mk1/2 fiesta forum but there is a guy on there called fiecos dan who has run several different engines of various sizes and states of tune using R5 turbo carbs and is something of an expert when it comes to modifying and setting them up, im sure he would be able to give you a lot of information or at the very least a look through his built thread will certainly give you some food for thought

[Jimmy_GTT]

I have the Haynes Solex and Pierburg carb repairing book. I'll get the french RTA books which covers GTT carb. I have a 30 site pdf of the overhauling.
I have about 5-6 spare carbs and I'm planning to cut one into pieces to see the inner channels.
I'll try to go step by step covering each little part of the carb. Writing down how it is working and what are the common problems.
I'll try to start asap and will try to make an english draft of it. At least collecting the known problems and solutions.

Thanks for the hints!

[michael tierney]

make sure u dont cut up a decent carb body(no flange cracks)i have a few spare cracked ones!!

[Jimmy_GTT]

Can someone please help me with the following questions?
In the data table of the carb there is:
'pneumatic opening (mm) - 6.4 full choke non adjustable'
What does it mean?

What is the difference between carb 854 and 931?
As I know 854 is for the phase I, 931 is for the phase II, but all jet sizes, settings are the same.

Thanks!

[SIPI]

The difference is CO %

854: 1 to 1.5
931: 1,5 +/- 0.5

I send the data sheet to you

[Jimmy_GTT]

The difference is CO %

854: 1 to 1.5
931: 1,5 +/- 0.5

I send the data sheet to you

I have seen the idle CO, the question is what differs in the 2 carbs?
the idle CO is only a setting in the CO screw.
But what do these numbers mean? 854 v. 931

[Jimmy_GTT]

C'mon Mart, doctor of Solex 32DIS.
You might know the answers. ;)

[Karlos]

I have seen the idle CO, the question is what differs in the 2 carbs?
the idle CO is only a setting in the CO screw.
But what do these numbers mean? 854 v. 931

Refers to production/year :)

854 is Phase1 Carb
931 is Phase2 Carb

++++++++++++++++++++++++

I should read past/previous post!

[Russ B]

This is helpfull if you havn't got it already

http://www.rtoc.org/files/Technical%20Files/Solex%2032%20Dis%20Carb%20Information/karburatorsolex_ang.pdf

[Jimmy_GTT]

Thanks Russ, but I already have it.

What I've found is that 854 and 931 is the solex reference number of the carbs. And for the different engine numbers solex assigned a different carb reference.
So 854 is for the C1J782 and 931 is for the C1J788
And the Swiss edition C1J784 had Solex 32 DIS 860. (Choke tube 24mm, main jet 115, air compensator 135, idle 46, Enrichment 80)

[Mart]

Hi Jimmy,

Sorry mate, I didn't see this thread before (you can always PM me though :) )

Yes, 854 & 931 are simply the Solex reference numbers for a given engine application. The only difference I could ever find between those 2 carb's was the idle jet size (44 vs 45).

The R11t had a different carb as well (I don't have the Solex ref' number to hand though, soz). Slightly smaller main jet (117.5), a larger a/c jet (110) & a 24mm main venturi.

For better mpg/leaner off-boost fuelling, I used to run an R11t main jet on my old Raider's carb, and I found I could run a bit smaller than that (main jet wise) with Whitey's carb.

As for the 'pneumatic opening...', I believe that's with regards to the auto-choke that was fitted to some n/a engines. I've never had one apart, so couldn't comment what the '6.4mm' relates to though.

[Jimmy_GTT]

Thanks Mart,

interesting what you are writing about the idle jets because in the Solex documentations what I have found (and even in the french Revue Technik automobile) the same 45 idle jet is written. But I also have some 44 idle jets from somewhere. :)
And it could explain the idle CO range difference.

I also think that the pneumatic opening should refer to the auto choke system. I have only seen such a carb on a R9 Turbo.

I have measured all the jets in Whitey and the main was std. 120. But anyway runs perfectly! ;)

By the way Whitey had his Hungarian exam on Monday. Tomorrow or the day after she will receive the Hungarian license plate also.


Does anyone know what is the number 18 or 21 or 24 on the choke lever?
And I have found choke plates with number 8 or number 10 on them.

[Mart]

Don't believe everything you read :)

Yep, 120 in Whitey now, but it ran a smaller main jet before we parted company ;)

Make sure you keep Whitey's GB licence plates ;) :agree: The day will come...

The choke plates with 8 or 10 stamped on them could be the diameter of the plate hole?

[Jimmy_GTT]

Licence plate will be kept, don't worry. ;)

No, the hole size is the same. I've measured them.