Thread: S2A bit and pieces.

I have just finished uploading a whole bunch of high-resolution engine and gearbox photographs taken during the restoration process of my vehicle -over 60Mb worth. I get the impression that people around here like threads with lots of photographs, so this might be appreciated. I guess this could be considered Land-Rover pornography

http://www.glensstuff.com/68s2a/enginerebuild/
http://www.glensstuff.com/68s2a/gearbox/

Just follow the categorized folders directed to by the links above. Clicking on an "XX.jpg" photo filename should open the respective photo in your browser (use browsers "back" button to get back to main folder).

Cheers,
Glen

Originally Posted by 68s2alwb

......
Other than having rebuilt this Solex, I have no hands-on experience with any Holden 6 or original Landy carburetor, but just from studying the specs and operating principles I figured that the Solex was the best pick of the three most obvious options (Stromberg, Zenith or Solex).

The Solex was fitted to Landrovers up to the early sixties, and as far as I can see the only reason for change was the merger of Solex and Zenith. It was succeeded by the Zenith, and later in the 2.5 by a Weber, although I don't think this carburettor was ever sold in Australian assembled vehicles, so these are very rare here. The Stromberg was never fitted to this engine by the manufacturer, but was a common repair, as good, cheap, Strombergs out of Holdens that had rusted out were readily available far cheaper than a repair kit for a Solex or Zenith. They were never very satisfactory in this application, even if fitted with the optimal jets for the Rover engine not the Holden. But they did work (usually).

In my experience, the only difference between the Solex and Zenith is that the Zenith is a little easier to get parts for and easier to work on and understand, but is probably more prone to problems, mainly warping of the top cover, and the O-ring seal is critical.

(This discussion applies only to the four cylinder engines - the the six and V8 used either SU or Zenith-Stromberg constant depression carburettors)

Funny story; I spent (wasted) a whole Saturday morning running around all over the place to no avail trying to find a (fuel line) hose-barb fitting that would screw into the Solex. It didn't occur to me to even try a metric fitting. Doh!

Surprisingly, it seems that most English carburettors have been metric from the very early days (~1900) when the centre of motor expertise was in France, although I suspect most threads are probably BA or French rather than ISO, and in fact Solex was a French company, and Zeniths original designs were French. (It is usually possible to screw these into each other, even though the thread profile angle is different)

John

In exasperation the last port of call that Saturday (actually then in the afternoon) hunt to find a suitable fuel fitting for the Solex was the performance shop I last had my modified 383 (not in a Land-rover) dyno tuned at. The shop owner looked at the carb and said "Solex, French, metric"!

The internal thread that originally accepted the "Special bolt" for the "Banjo union" is M12 with a thread pitch of 1.25mm (well that's what seems to fit perfectly anyway). I know this isn't the original fuel fitting, but I'm not particularly enamored with that hard-plastic fuel line to the carb that was the original equipment.




The Solex looks to me a more sophisticated design than the Zenith, with better accessibility for accurately tuning the fuel metering over the entire operating rpm range of the engine; jets for the various circuits (idle, main, "economy", accelerator pump) are all accessible. It's been a while since I looked but I don't think that is the case for the Zenith.

Another thing is the Zenith has a primitive "choke" in the literal sense - a butterfly that simply suffocates the engine to create greater vacuum to draw more (richer) fuel. The Solex on the other hand has (effectively) an auxiliary carburetor that supplies the enriched fuel supply when cold, rather than a butterfly that restricts air flow to the engine (much like my DCOE Webers).

I always have my newly built engines tuned on a chassis dyno. The LR won't be an exception, even if only to make sure the carburetor is working as good as it should be.

Originally Posted by 68s2alwb

In exasperation the last port of call that Saturday (actually then in the afternoon) hunt to find a suitable fuel fitting for the Solex was the performance shop I last had my modified 383 (not in a Land-rover) dyno tuned at. The shop owned look at the carb and said "Solex, French, metric"!

The internal thread that originally accepted the "Special bolt" for the "Banjo union" is M12 with a thread pitch of 1.25mm (well that's what seems to fit perfectly anyway). I know this isn't the original fuel fitting, but I'm not particularly enamored with that hard-plastic fuel line to the carb that was the original equipment.

Hello 68s2alwb ,

So does this mean that your problem is solved and you are back on track to getting your fuel delivery issues sorted out?

If so congratulations .

Series Land Rovers tend to breed either desperation, patience, insanity or blind faith.

Kind Regards
Lionel

Originally Posted by Lionelgee

Hello 68s2alwb ,

So does this mean that your problem is solved and you are back on track to getting your fuel delivery issues sorted out?

If so congratulations .

Series Land Rovers tend to breed either desperation, patience, insanity or blind faith.

Kind Regards
Lionel

LOL, yep all sorted. I had to put a re-build kit through the fuel pump (the one-way valves were leaky and the pump couldn't keep the carbie float bowl filled with a bit of sustained engine revs) but she's all hunky-dory now.

Incidentally, the fuel pump takes the same M12/1.25-pitch fittings. I bought the fittings from here: Speedflow - Manufacturer of Aluminum and Steel Hose Ends and Adapters - Australia



Though the fancy blue anodization does look a bit "hotrod" and out of place in the old girls engine bay............

Originally Posted by 68s2alwb

.........
The Solex looks to me a more sophisticated design than the Zenith, with better accessibility for accurately tuning the fuel metering over the entire operating rpm range of the engine; jets for the various circuits (idle, main, "economy", accelerator pump) are all accessible. It's been a while since I looked but I don't think that is the case for the Zenith.

.........

I'm not sure that more sophisticated is how I would put it. Rather the Solex operating principles are more elegant. But it does have the drawback that there are a number of diaphragms that are potentially susceptible to failure due to their being designed for hydrocarbon fuels, not ethanol, which is likely to be in any fuel we buy today.

The Zenith has only a single sealing O-ring that is submerged in fuel and critical to operation.

You are right, the Zenith needs the top removing to access any jets. As I said, in my experience, as far as performance goes, there is no significant difference.

John

Well, the cold-start system on the Solex is definitely more sophisticated than the Zeniths choke butterfly and I don't see anything in the Zenith that would be equivalent in operation to the "economy" circuit in the Solex, which serves to improve the accuracy of the fuel metering over the engines full operating rev range.

Though how much the latter translates to better out-right performance in comparison to the Zenith is not necessarily significant; a more apparently sophisticated (or rather complex) design is not necessarily better - it depends on the implementation.

Though I know that the primitive operation of a number of popular Stromberg models doesn't help with their performance. If the single-throat Holden model popularly fitted to these Land-Rover engines is based on the same functional design as the twin-barrel Stromberg WW model fitted to the Holden 253 V8, then that can't be a good thing.

The WW couldn't meter fuel accurately over the engines full operating rpm range (they progressively leaned out), so as a compromise the factory had to set them to run rich at low revs (you of course don't want to compromise the other way around - properly tuned down low but lean up top). 253 engines fitted with the 4-barrel Rochester 4MV (Quadrajet) that could actually meter fuel properly not only produced more power but returned significantly better fuel economy around town - so the cheaper, lower-performance option was actually a false economy for the buyer.

See if you can find a description of how a Zenith works - it is actually fairly sophisticated, although certainly different to the Solex.

John