Is this Solex 40DDH Side Draft toast?

[CDN OpelNut]

So I've got this Solex 40DDH sidedraft and I've located a rebuild kit on E-Bay for it. I took a couple of screws off it and it looks pretty rough. As you can see, the diaphram is full of white crud. I don't mind spending the $20 for the kit if there is some hope of getting it working, but don't want to waste my time. Thoughts?

[GTJIM]

As this carb came from Germany there is a fighting chance that it is correctly jetted for the Opel motor.
Soak it in one of those pans of carb cleaner that are available - or just use standard Coke-a-Cola (TM). That should remove all the white powder and then you can assess if there has been too much corrosion.
Carb Rebuilders can 'resurect' quite terrible looking carbs ... and make them look like new.
An interesting project - keep us informed, Please!

[CDN OpelNut]

Thanks Jim. I am kind of leaning toward doing it simply because it would be somewhat rare. It came bolted to an Irmscher SSD manifold and fits nicely on the 1.9 head so it was on an Opel at one time.

[tekenaar]

Originally Posted by CDN OpelNut Thanks Jim. I am kind of leaning toward doing it simply because it would be somewhat rare. It came bolted to an Irmscher SSD manifold and fits nicely on the 1.9 head so it was on an Opel at one time.

Yeah, definitely save it. That corrosion is aluminum oxide and is normally more of a surface film than actual 'pitting' corrosion. That would make a wonderful installation and should even fit in a GT with a bit of minor work . . . no major heater box surgery! Here's my 2.2 Steinmetz SSD with a Dell'Orto DHLA48 for inspiration:

[CDN OpelNut]

Your installation and comments are the reason that I searched out the SSD manifold in the first place! The Irmscher unit looks similar to yours and I love the look. This will be going on my 2.4 conversion, currently underway.

[baz]

Originally Posted by CDN OpelNut This will be going on my 2.4 conversion, currently underway.

one 40 ddh might be a bit wimpy for a 2.4 engine what size chokes are in it

[tekenaar]

Originally Posted by baz one 40 ddh might be a bit wimpy for a 2.4 engine what size chokes are in it

I agree with baz, probably has 32 chokes in it (typical for 1.9 SSD40 carb), should be at least 34 choke and complete rejetting for larger displacement engine if sticking with that carb. Larger carb will dictate welding and reboring of manifold.

If you look closely at my pic above, you'll see the welds at the carb mounts of the manifold. Mine was for a 1.9 and also used a 40mm carb originally, the most common setup used. I had it bored and welded for a 48mm carb, largest made by Dell'Orto.

[CDN OpelNut]

OK - Getting depressed. I am assuming that to determine the choke size, the measurement is done at the narrowest point. I put my telescoping gauge down the venturi and measured around 28mm.

Is this the best way to tell or is the measurement done at some other point.

[baz]

webers have the size cast into the choke insert , dont know about the solex but it may have it , the 28mm sounds about right for a standard 1.9 with no add ons

[tekenaar]

Originally Posted by CDN OpelNut OK - Getting depressed. I am assuming that to determine the choke size, the measurement is done at the narrowest point. I put my telescoping gauge down the venturi and measured around 28mm. Is this the best way to tell or is the measurement done at some other point.

That's the correct place to measure it, but as baz said, size will be indicated on the choke itself though that requires removal of both aux and main venturis (choke). At each barrel, there should be a screw and jam nut on the outside that retains the aux venturi and main venturi below it. Loosen this nut and screw and you'll be able to slip out the aux venturi and then the main venturi (choke) below it (aux venturi keeps it in place).

28mm choke is small for an SSD40 carb, 32mm is more the norm in all the ones I've seen, though your Solex is the first I've seen as an SSD. Can't imagine much difference in general between the SSD40 carbs used, Weber, Dell'Orto or Solex.

[CDN OpelNut]

This is the choke insert from the carb. (At least, if this was a Weber, this is the piece identified as the choke on those diagrams)

It has no markings on it, but the internal diameter is 37 mm. Does this mean the choke size is 37 despite the fact that the venturi narrows a bit toward the butterflies?

[baz]

no the size is the smallest dia. inside the choke bore

[CDN OpelNut]

Made some progress. The parts are labeled a bit different thanthe Webers. I got the venturi out and it is stamped 27.5 so I'm on the hunt for bigger ones.

[baz]

you could have a M/C shop open them out to 34/5 mm on a lathe and polish them if you cant find any
they just need to be opened to the same point/shape in the bore for the venturi to work

[tekenaar]

Originally Posted by baz you could have a M/C shop open them out to 34/5 mm on a lathe and polish them if you cant find any they just need to be opened to the same point/shape in the bore for the venturi to work

I've found the "not over 85% of throttle bore" main venturi sizing to be a good general rule of thumb on SD carbs, single or dual. AV (Aux Venturi) signal strength is diminished when using larger chokes, which directly affects mid- and upper-RPM mixture control critical in producing optimum engine power. You're probably not going to find bigger chokes for your Solex SD40, so you'll have to resort to machining the existing ones to 34mm. All that's required is enlarging th ID, so any machine shop can do this in just a few minutes on a lathe.

Caveat: Your 2.4 capacity may offset this 85% rule somewhat . . . bigger pump, more air flow! Personally I wouldn't increase the ID of your chokes over 34mm as it will limit its possible future use on a smaller displacement engine. You never know!

[GTJIM]

The internal profile of the venturi is quite critical - just 'hogging' them out to 34mm will not be too good!
Try alpha1750 on eBay and see if he can supply real 34mm Solex venturii - you may be surprised how inexpensively he can supply parts ... and how quickly they arrive.

[CDN OpelNut]

Thanks Jim - I do have alpha1750 tracking down a few items for the carbs including the 34 mm chokes. Keeping my fingers crossed. The internals of the carb are actually quite clean so if I can get the parts and figure out all of the connections it should work.

[dapbmw]

btw they are german solex ddh's so the ones alfa1750 sells in fleabay are italian and the parts are not interchangeable with the german ones, are you sure you got the right gaskets? they should say solex 40 ddht.

i have been rebuilding carbs for over two decades now and i do a lot of the german solex ddh/t's for bmw 2002 guys. i am in whitby,on. you are in bc? email me. i do have the proper gaskets too.

dave

[CDN OpelNut]

Well - it's all a matter of timing I guess.

I have discovered the hard way that the Italian parts won't fit. I really had no idea that the carb I have was German until I started to research it a bit.

I found a source of the parts in Germany and thanks to tremendous help on this from GT.com member Heimue, I managed to order, just tonight, a rebuild kit and some jets for the carb. I am assuming that it's original application was a VW K70. Is that correct?

The 32mm chokes that I got from Italy fit fine so I am OK for those. I will certainly get in touch with you if I need anything.

If you can PM me cost on rebuild kits etc, I can probably catch Heimue before he orders them for me if there is a price diff.

Thanks for the offer. I will probably take you up on your expertise at some point.

Corey