This quiz is open to all members except Jim Kaufmann.
Can you identify at least 2 mechanical features on this Solex 40PII that are not stock? (for this quiz, consider finish as not mechanical). Sorry for the bluriness of one pic, but it is good enough for this quiz.

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Phil Planck

Solid shaft in a split-shaft body.
That's one; don't see the other.

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Aluminum sealing washer under float level plug should be fiber washer.

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Vacuum connection; not used for 356s. It's a 912 carb body.

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Spring perch is on the wrong bolt.

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Missing spring clip on throttle shaft on right side

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1964 356 C Coupe, Togo/Fawn, Chassis 126634
Enjoy some pictures of my Togo 356 at:
http://www.flickr.com/photos/8292359@N0 ... 3749/show/

(1),Throttle arm, its one modified from a weber , ok already mentioned (2),throttle return spring is usually mounted to top left 10mm hold down bolt & spring should be turned around at throttle arm. Having said that I usually like the spring mounted as pictured as it adds a better response for a lighter & quicker opening of the butterflies while adding enough tension to return the butterflies to their closed position.

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I will give this till the end of today, and then post my answers. Vic got one of my answers, and someone else was close. Not the spring location, and not the fiber washer. When I post the answer, I will have a question which hopefully one of you can answer. This is an "educational" quiz.

Phil

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Phil Planck

Ok rethinking your original question. I would conclude these 2 items (1) butterfly shaft & (2) idle adj. tab. all other items could be factory equip.

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Well, it's not the end of the day, but I am too tired to wait until later. Max got both correct. Ron, and others correctly stated it was a converted 912 split shaft however, I never stated it was a 356 Solex, only that it was a Solex. Anyway, after hearing the Carb Rescue presentation at the Cleveland ECH in 2010 I have been looking for a decent set of 912 carbs to put on Foam Car's S90 engine(currently being exercised in my 55 coupe until Foam Car is done). The one shown above, and its mate were advertised in our classifieds and were stated to have been converted to solid shaft by Al Cadrobbi. Well, I thought that would be neat to have something Al worked on, so I bought them. It appears that Al used a 356 solid shaft and accel linkage to make the conversion. It also appears that the stock 912 bushings were used(which I have read were not that good from a wear standpoint). Anyway, I did not take a real close look at them until it was time to install them. With our July in March weather, I decided to go ahead and install them and try them out. What bothered me upon closer inspection, was that the idle speed screws barely touched the throttle lever tab(pic below, not necessarily in order of discussion). The 912 casting boss that the idle speed screw threads into is about 1/4" or more higher than the 356. Not sure why, maybe to provide finer adjustment of idle speed, since the same amount of screw turning would move the throttle a little less.

Based on this I had an email discussion with Jim Kaufmann who advised that the 912 throttle levers, which have a higher tab to mate to the higher idle speed screw would not work. Jim then emailed his throttle lever source, Paul Grusche, who is in Dexter, MI and asked him to contact me. I talked to Paul, and he said that the slotted hole for the shaft in the 912 lever is about 15 degrees different than the one in the 356 lever. So, as can be seen below, the 912 idle speed tab is at a different angle(15 degrees or so) relative to the throttle lever arm than on the 356 lever.

So, what is the poor soul owner of this hybrid Solex to do, as probably not many like this exist? What I did was extend the tab another 1/4" so there was full contact with the speed screw. The tab is very close to 1/8" thick, and I have welding class coupons left over with various thicknesses, one being 1/8". I cut off 1/4" slivers and made a sharp 90 bend to match the tab bend. Welded in on, filed the weld smooth and painted it gold(no yellow cad platers up here in northern MI).

So, what I would like now to know from you very observant partcipants, is why is the 912 throttle shaft slotted at a different angle? It also looks like the tab is at a slightly different angle on the 912. This may be to insure good clearance to the idle speed screw, because by extending the tab like I did, geometrically causes some loss in back off adjustment. In other words, extending the tab would require the idle speed screw to have to be backed out to get the same throttle opening.

Oh, and I know the return springs are not in the factory location. I just happen to like how they work in that location better, plus, I am keeping a count of how many times I have been told they are not in the "correct" location. At least now I don't even have correct Solexes.

And, although it was a short test run yesterday, these converted 912s have not exhibited the flat spot I had with the S90 Solexes. That flat spot could be just an issue with these particular S90 Solexes that has not been corrected, but so far I really like the 912 Solexes and the fact that I have a little of Al Cadrobbi's work on Foam Car's engine.

Hope at least one of you learned something new.

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Phil Planck

Phil,
Re: the T spring clip location.
At idle, the butterflies are subject to the highest delta air pressure load. At that point, the return spring pressure needs to be the highest possible; 90* to the axis of the throttle lever.
If it is not, you may find the idle to be inconsistent as the delta air pressure overcomes the weakened spring load on the throttle lever and prevents the butterflies from fully closing.
It only took Alan several years of explaining this to me 'way back when until I finally understood that the idle speed was affected by such matters. And it is.

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Hi Phil

Didn't the Last of the Line 912 Solexes have the extra Idle Transition Holes, makes for a much smoother Caburettor, Together with Better Throttle Spindle Bearings. When converted to Quality Solid Throttle Shafts. You have the ultimate 40P11-4 What Serial Numbers are they?

Jay

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Ron LaDow

Very interesting info regarding the high spring force needed at idle.
I had not thought of that. I borrowed a friends accurate trigger pull gauge(0-8 lb) and measured the spring tension in my "incorrect" position at 2.62 lbs. and the tension in the correct position at 3.25 lbs. Next I looked at the angle where the spring mount tab is to the center of the throttle shaft. Surprisingly, it is almost horizontal, even though the lever is at an angle. Then I measured the angle of the spring in the "incorrect" location at 10 degrees off vertical and in the correct position at 25 degrees off vertical. Calculating the vertical force on the lever(90 degrees from the line through spring tab hole and center of throttle shaft) gives 2.60 lbs. in the "incorrect" position and 2.68 lbs. in the correct position. Hopefully that .08 lb. reduction at idle won't get me in trouble.

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Phil Planck

Phil,
To be honest, I'd never measured the spring pressures; just looking at the geometry, I'd have guessed a bigger increase.
But I'm unsure why the geometry counter-balances the greater pressure; any idea what I might be missing?
Regardless, thanks for the data; that >5% reduction isn't going to cause any problems.

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Phil,
While you are at it with tension gauge in hand, it would seem even more interesting to measure the force need to keep the throttle closed at idle. My thought was to disconnect the drop arm and the spring on one carb. while the engine is at idle, warmed up of course, and measure the force required to keep the throttle closed. My bet is that it is very small, in fact the throttle may even stay closed by itself. If you could prove or disprove this theory I’d be most grateful !

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