Stripping/cleaning DATR carb on 2 litre Spider

[mangocrazy]

I'm back in France for a couple of weeks and have decided I need to get serious obout getting the Spider running again. To that end I've decided to give the carb a degrease, ultrasonic clean and overhaul. I spent half an hour or so getting as much external muck off as I could using a mixture of carb cleaner and degreaser, then stuck the non-rubber parts in the ultrasonic tank for an hour.

Unsurprisingly, they came out a lot cleaner than they went in... One thing I did notice was that the fuel shut off solenoid was pretty much falling out of the body of the carb, making me wonder if it was even capable of doing its job. I've taken a photo of the offending thread and it ain't pretty. I suspect it vibrated loose and then chattered away for years. What are the implications of having a non functioning solenoid on a car with an electric fuel pump? Apologies for the fuzziness of the pic - it's quite a high magnification.

All advice welcome...

I also fairly quickly discovered why the auto choke never seemed to work; there was no coolant flow due to one of the spigots being totally blocked.

[HFStuart]

If it decides it wants to run on without the cut off it'll drain the float chamber to do it - whether the fuel pump is running or not. Handbrake on and first gear will solve it but it's clearly not ideal.

The biggest problem with that is that it is a big air leak  - you could probably remake the threads with JB weld or similar but it looks too far gone for an insert. After 40 odd years the carbs are susceptible to spindle wear and occasionally distortion of the base - check those. If they're near perfect then it's worth trying to save the carb otherwise I'd suggest looking for a good used DATR or DMTR - or a new one if you're feeling flush.

[mangocrazy]

I was thinking about the JB Weld route, and with the carb off the car and in bits now would be the time to do it. Alternatively, what would be the consequences of just blanking the hole off completely and doing without the fuel solenoid?

I'm loath to spend much cash on it, as the medium term solution is a pair of new DCOE Webers on a completely rebuilt engine. The engine in the car at present is just something to keep the car going until I can swap in the refurbished motor and carbs.

[HFStuart]

what would be the consequences of just blanking the hole off completely and doing without the fuel solenoid?

Other than it might on occasion run on and you'll have to force it to stop by putting it in gear, none that I can think of. You'd just need to make sure it's airtight.

[mangocrazy]

what would be the consequences of just blanking the hole off completely and doing without the fuel solenoid?

Other than it might on occasion run on and you'll have to force it to stop by putting it in gear, none that I can think of. You'd just need to make sure it's airtight.

OK, so that's the worst-case scenario. I can live with that. I'll have a closer look and see if it's possible to get the solenoid working as intended if the JB Weld is packed into the gap. I'll also try and bench test the solenoid to make sure it's still working as intended then clean up the carb body and solenoid threads with carb cleaner and a tooth brush and then mix up some JB Weld and apply it.

If that doesn't work I can at least just blank off the hole where the solenoid should be.

Thanks for the help, Stuart.

[mangocrazy]

There is realistically no way that the solenoid will screw into the carb body and make an airtight seal, the thread is too far gone. So I'll be blanking it off as best I can and making it airtight, using JB Weld. I have a cunning plan involving an M4 button head allen bolt, 3 x M4 nuts and an M4 washer.

And a generous quantity of JB Weld.

More pictures as it happens...

In other news I've ordered a service kit for the carb from the NL arm of Eurocarb (Eurocarb UK only ship orders above £150 to the EU now, apparently). Another casualty of Brexit.

[capriblu]

I think Id want to try and get the solenoid valve operational even if it is somehow incorporated into the interim bodge       Cant you just locate the valve in the correct position and use some form of adhesive/sealant to hold and make airtight?

[mangocrazy]

The problem is that the valve appears to have been loose in the housing and 'chattering' for a considerable period of time. In doing so it's made the boss on the carb distinctly oval and even cut a new off-centre thread into the boss. I've tried carefully screwing it in, but it just drops out. Heaven knows how the car ran with it like that. Even if I could fill the boss with something like JB Weld and try to re-tap the thread, the existing thread is so deformed and weakened that it wouldn't seal. Plus I'd have to be quite accurate in any tapping operation.

I've thought of using silicone plumbing sealant to bodge it up, but I very much doubt that would hold, plus I'd have difficulty lining the solenoid plunger up correctly. And I don't even know if the solenoid works properly. The centre part that moves and makes the seal dropped out as I removed the solenoid from the carb, so I suspect it's faulty anyway.

Hence my plans to seal the whole thing off with JB Weld...

In other news, I've fitted all the 'upgrade' jets you recommended, so when it does finally make it back on the road hopefully it will be nicer to drive. Once the service kit arrives I'll fit that and get everything reassembled. I'm hopeful that I can at least get the engine running before I have to head back to the UK in a week or so's time.

[JohnFol]

I found my solenoid works (but needs slight pressure on tip to activate it), gets energised when on car, but has no effect on running when disconnected, i.e. engine still runs.

When you mention the "seal" when you took it out it makes me think I've also dropped a bit. Do you think it was like a washer, or more an internal smaller rubber ring?

[mangocrazy]

I think I may have confused the situation unnecessarily regarding the solenoid. Below is what mine looks like. I don't know much about solenoids, but I'm fairly sure they aren't supposed to be in two parts...

[JohnFol]

So I am missing a washer and unless it's buried in the carb somewhere, I'm missing a rod, spring....

[mangocrazy]

The service kit for the carb arrived yesterday (took 5 days to arrive from Holland) and I've replaced all the parts in the kit that I could identify including the float valve and seat, nylon fuel filter, base and float bowl gaskets and diaphragm. I didn't replace the circular gasket and 4 o-rings as I couldn't see for the life of me where they went and I wasn't about to strip the carb any further.

The carb is now essentially ready to go back on the car, but I'm fretting about the auto choke and whether (or not) the coiled spring which locates into a fork in the choke mechanism needs pre-tensioning or not. I've just assembled it with the spring fitting into the fork but not under any tension. Does anyone know what the correct state is for this? 

Anyway, I think I'll re-fit the carb and see what happens. At least if it does need tweaking the choke unit is external to the carb and more readily accessible.

[HFStuart]

On the float needle valve did you check the  size? Most are 1.5 but the Beta is supposed to have 1.75. I used a new needle on an old seating part.

[mangocrazy]

The replacement unit is a 1.5 - what kind of problems would this cause? I assume the 1.75 has a larger jet/nozzle size than the 1.5...?

[HFStuart]

Drive it hard and you might find it drains the float chamber.

[mangocrazy]

Yes, guessed as much. Fuel starvation under full load? To be honest I doubt I'll be driving this engine that hard - I just want it reliable enough so I can get it back to the UK and replace the 'donor' engine with the refurbished original, which will have a pair of DCOE 45 Webers.

I've sent an email to the parts supplier in NL asking if they can supply the correct 1.75 part, but my main concern is initially just to get the engine running reliably again. I'd prefer to run a new float valve and float needle combo rather than a mix & match of old and new parts.

[peteracs]

On the auto choke I did not pretension. Easy to test, when cold pressing the accelerator should set the choke flaps and after warm up the flaps should drop down on blipping the accelerator.

Peter

[capriblu]

I think you do need to "pre-tension" in a sense in as much as this is what is needed to "spring" the choke flaps closed when cold.

The tab on the end of the spring locates in the slot on the notched choke cam device.  With this in place then as the spring housing is subsequently offered up to the choke body then a certain degree of movement against the spring (i.e. pre-load) is required as the housing is turned to match up with the the three mounting screw holes and alignment of the single line markers on the body and housing.

[mangocrazy]

Yes, I'm tending to the view that a certain amount of pre-tension is needed (not a lot, but some) just for the spring mechanism to operate as intended.

However, all these finer points have been overtaken by events, which I'll detail further in the 'Member's Cars' section. Suffice it to say that my fiddling with the carb stops here for the moment.