Solex 32DIS questions

[pigpen]

First post!

Hello

I am sure this has all been covered before, and I have pretty much worked out what everything is on the carb...

But could someone clarify a couple of things for me?

The vacuum fitting on carb, which normally goes to the turbo... does this provide both vacuum and boost, or just vacuum? If the former then I can use to reference a distributor with both advance and retard (a SAAB unit)...

by now you may have realised, this is not on a Renault! Apologies, Its a 1954 VW with charger, and I want to run blow through so the 32DIS is my best option.

The petrol overflow thingy... does that connect back up to the fuel system? On the diagram I have seen it suggests that it connects to boost from the inlet! but I am guessing that these are just dodgy lines.

Boost is fed into back of accelerator pump, that makes sense...

My other big question is... on the plate that has the throttle butterfly there are two big ports that are for water heating... and then another that points up at an angle which for the life of me seems like it vents out to atmosphere... surely this can not be correct?

can anyone clear up for me what that is? and my question about the vacuum... and possibly confirm my other thoughts...



thanks for listening, hope you can help!

[Trevhib]

I can answer your question on the overflow (if I've understood which pipe you mean). It just vents to the atmosphere, down the back of the GTT engine and towards the floor. It's redundant until one of the gaskets fails (I don't know which one), and it's designed to route leaking petrol away. So you need to route yours to somewhere there is no chance of it leaking onto something hot.

The water circuit in the base of the carb is there to ensure the different metals in the carb body warm up at the same rate. If not fitted, it's 'possible' while the car is warming up, for the throttle spindle to stick open when you press the accelerator.

Can't answer your question about the vac fitting conclusively. I'm pretty sure there all the outlets are either boost only or vac and boost, i.e. not vac only but I could be wrong.

As for the thing that points upwards, that sounds like the mixture port, in which there should be a screw with a rubber o-ring. You can still get these bits as a kit. GTT's are set-up by screwing all the way in and then out by a turn and a quarter.

[pigpen]

New poster! (less than 10 posts)

perfect

thank you so much for your prompt and informative answer!

I guess I can warm the base of the carb with exhaust gas, as all Air-cooled VW used to with the manifold...

Wait and see on the vacuum post though... I will tap the manifold first and then use the carb vacuum if it gives both signals...

Unless it could be used for the boost gauge if it has both???

and I see now about the screw... Pretty sure it will be in the box somewhere.

I will be buying a new carb from gt-turbo-spares so I am lining up first with a less than perfect one, from which this screw was missing obviously.

once again, thanks for the help!

[Trevhib]

No probs. Hopefully others will be along to answer anything outstanding

Warming the carb base with exhaust gas - Since nobody here has ever done that I can't really say if it's a good idea or not. It's probably something you should only look at doing if you're having throttle spindle problems, which is unlikely and only happens in winter time anyway.

The carb has an OE boost gauge take-off as standard (it's one of the ones on the left hand side of the plastic 'lobster' top), and it only registers positive pressure but for after-market gauges, most people tap into the pipe that runs to the ignition unit because it comes from below the butterfly and so registers both vac and boost.

Best of luck

Would be good for you to post some pics of your project now that you've paid for membership!

[pigpen]

New poster! (less than 10 posts)

yep. will do.

here is a run down for now.

1192cc 30hp 1954 engine
Reworked heads with 40% more cfm
Bosch Distributor with vacuum advance and boost retard using a SAAB can.
VW 1500cc inlet manifold adapted to suit.
AMR300 charger making 6lb boost.
8:1 CR.
Bosch vacuum controlled bypass valve.
merged exhaust header.
R5 GT turbo carb

pretty simple really!
Should take it up from 30hp to 60hp pretty easily.

thanks for the help!

[Trevhib]

Really interesting S/C project. Best of luck with it!

If you want to chart your build on this site (or copy it over from a VAG site etc), start a thread on this board: https://www.rtoc.org/boards/forumdisplay.php?f=13 (Projects & Restorations)

[Alex]

Do you mean the pipe that goes from the carb. to the actuator? If so that will give vacuum on idle/off boost and will provide boost to the wastegate on-boost. There is also a smaller pipe on the same side on the inlet manifold that goes to the AEI module. Whether or not you can use these pipes for your needs I'm not sure but they do provide vacuum

[pigpen]

New poster! (less than 10 posts)

yeah, that is the one... so if it provides both vacuum and boost signals I can use it for my distributor, but maybe a feed from my inlet manifold would give a more immediate signal of what the engine is doing and so be better for distributor?

either way, I will find a use for it... boost gauge most likely. Has anyone connected one to this before and read both boost and vacuum?

[Trevhib]

Just for clarity.

The line that goes to the actuator port, runs from the right hand side of the plastic lobster-shaped inlet. This only sees boost as it's above the throttle.* It's effectively the same place where the OE boost-only gauge takes its reading from.

The line that goes to the AEI module (the ignition module), runs from the right hand side of the carb's base, beneath the throttle. This sees both vac and boost and it's what we call 'at manifold pressure'. It gives the boost pressure that the engine is experiencing because it is after the pressure losses of the boost run/intercooler. Most people use this line to 'T' into for after-market gauges that display both vac and boost readings.

There is nothing that I know of that sees vac-only.



*Alex, it looks like one of us has this wrong?

[Alex]

Trev, he said 'from carb' rather than 'carb top' so I assume he means the pipe on the right hand side of the carb (as you look at it) near the AEI line. There is normally a T-piece on standard setup from the carb top.

Here is mine for clarity. You can see the pipe from the side of the carb to the actuator. That's the pipe I'm talking about. Note the AEI line near it also.

[Trevhib]

Hi Alex.

It's been a while since I has a GTT carb in my hand. I'd fogotten there are two carb-body connections on the right hand side. The AEI one below the throttle and another one above the throttle, i.e. the one you have running over to the actuator as part of the cup mod I guess.

I thought the latter was above the throttle and therefore didn't give vac?

[Trevhib]

Pigpen, you might want to have a look at this too:

All about the 32DIS Carburettor
https://www.rtoc.org/boards/showthread.php?t=4734

And here:

Cup Mod
https://www.rtoc.org/boards/showthread.php?t=4756

[Alex]

You'll still get a bit of suck from the above the throttle on idle Trev. If you were to start the car up and whip the lobster off and put your hand over the it you'd be able feel it. Whether this is enough/correct for Pigpens conversion I'm really not sure.

I think it would most likely be better to use the AEI line if it's for advance/retard purposes? That is essentially manifold pressure or 'what the engine see's'. Most people use this line for their boost gauges also

[Trevhib]

Cool.

Yep, the AEI line is the one I'd use.

[Alex]

Incidentally I'd very much like to see this creation!

[Trevhib]

More help for Pigpen. I found these rooting around the site:



There's a Solex manual in the same folder:

https://www.rtoc.org/files/?path=Tech...20Information/

[pigpen]

New poster! (less than 10 posts)

thank you all!

I will be posting up stuff as I progress. Should I start a new thread? perhaps not.

I was talking about the connection on the carb.



I thought that was vacuum... and also possibly boost... maybe I am wrong...

But taking it from the manifold under the carb makes the most sense I guess as it is what the engine 'sees'. Should I just block this port off on the carb?

Here is rough schematic of what I am up to... neglected to draw in the intercooler though...

[Brigsy]

You can block off that fitting on the side of the carb thats above the throttle body, i took the brass fitting out and fitted a suitable bolt.

You dont need to use any of the fittings on the carb body - plumb your actuator into the compressor housing and use a boost reference to the fuel pressure regulator.

[pigpen]

New poster! (less than 10 posts)

surely I need boost into the back of the accelerator pump? This was the whole point of using this carb..... or have i got that wrong???

[Brigsy]

The acc pump leaks boost, i done away with the pipe on mine years ago with no ill effects. Search for the 'doris mod'. The pipe is only there to equalise the pressure on the diaphragm. I done a back to back test with my wideband afr gauge made no difference at all.

The acc pump only works on initial throttle application anyway the enrichment circuit on the carb adds more fuel when boost is put through the carb. That is what you need for your turbo conversion

[pigpen]

New poster! (less than 10 posts)

You know I was wondering about that.
When I took it apart, looking at it and how it is put together... it seems like it would do nothing but leak boost.
I will look into the mod... thanks sir.

Now to find some nice brass fittings to put into those ports!

[pigpen]

New poster! (less than 10 posts)

Any opinions about my carb heat plan...?

Obviously I have no hot water to heat the base of the carb with... but all aircooled VW use exhaust gas heat to preheat the intake manifold... could i just re route this to my carb???

[Trevhib]

Warming the carb base with exhaust gas - Since nobody here has ever done that I can't really say if it's a good idea or not. It's probably something you should only look at doing if you're having throttle spindle problems, which is unlikely and only happens in winter time anyway.

I'd definitely go without it first and only experiment with it if you find you're having throttle spindle sticking issues.

[Brigsy]

New poster! (less than 10 posts)

Any opinions about my carb heat plan...?

Obviously I have no hot water to heat the base of the carb with... but all aircooled VW use exhaust gas heat to preheat the intake manifold... could i just re route this to my carb???

You need coolant through the base of the carb. Don't run any at all, it should be fine without. I have ran my van for years without any carb base water heating.