Go to article on Solex Split Shaft Carburetor Conversion
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By John Jenkins
The single shaft Solex 40 PII were first used by Porsche in the 1955 1500cc Carrera engines installed in the 356. The 40 PII-4, came with the first Super 90 engines in late 1959. It was chosen because of the increased performance parameters of the Super 90. The 28mm venturi size of the Zenith 32NDIX used on the 1600 Super engines was not large enough to support the extra breathing capacity of the Super 90 engine. The following equation from the Solex Selection and Tuning manual explains why.
d - required diameter of the carb in mm Vh - the capacity of each cylinder in cm^3 n - the peak revolutions in 1000 rpms per minute
for 1, 2, 3, or 4 cylinders:
d = 0.82 x square root of (Vh x n) d = 0.82 x sq rt (400 x 5.5) d = 0.82 x 46.9 d = 38.5 (for 1720 cc engine d becomes 39.9 mm)
There is a simple multiplier, 0.8, to obtain the choke or venturi size. The results is the Solex 40-PII4, viz., 32 mm.
Split Shaft and Single Shaft, Compared
Now lets look at the...
By Tom Farnam
[Editor: it's common for the 356 engine to be difficult to start if it has been sitting for weeks or even several days, as modern gasoline is more volatile (evaporates more easily) than 50's and 60's era gas, resulting in the gas in the carburetor float bowls drying up. One solution is to install an electric fuel pump, but a less expensive solution is described below. See these links for information on electric fuel pump installation in pre-1962 cars (T5 and earlier) and in 1962 and later cars (T6). Another alternative is the Precision Matters "Primer Reservoir".]
If you want a primer pump, there is a very simple way to add one to your 356, without making any modifications which aren't easily reversible. It's only a primer pump, and will not operate your car if your fuel pump quits working, but it take care of the challenge of starting that car after it's been sitting a while. If the car has been sitting long enough to need priming, simply crank a bit ...
By Bob Slayden
When a car sits for a long period of time there is a tendency for fuel to evaporate from the carburetors, which can cause difficulties in starting. An electric fuel pump is one way to eliminate this problem. [Editor: A less expensive approach is a priming bulb. Another alternative is the Precision Matters "Primer Reservoir".].
Here are detailed instructions for installing an electric fuel pump in a 1962 or later 356 (For pre-1962 cars see this article). In this installation, the fuel pump is not intended to be used full time, so no pressure regulator is needed. Installation can be done in a couple of hours and is well worth the effort.
Installation in a T6 Car Placement of pump and wiring, view from wheel well Placement of fuel lines Pump placement, view from below Fuel line routing looking forward from wheel well Button before mounting under dash
JC Whitney Item #73ZX0906P-6v or #73ZX2807Y-12v[Ed: no longer available from th...
Three different installations by Barry Lee Brisco, Leo Hudson and Jim Neil
Here are three approaches to installing an electric fuel pump in a pre-1962 car (1962 and later cars see this article). In each case, the pump is located behind the floorboards so it is completely hidden yet close to the ignition for easy wiring. The pump is used as an aid in starting the car when it's been sitting for days and the fuel has evaporated from the carburetor float bowls (modern gasoline evaporates more easily that it did in the 50's), in case of vapor lock on a hot day, or as an emergency back-up if the mechanical fuel pump fails. A simpler and less expensive alternative is a priming bulb in the engine compartment, but that doesn't provide any back-up capability and doesn't look "period", if that's important to you. Another alternative is the Precision Matters "Primer Reservoir".
Barry Lee Brisco: I elected to mount a Pierburg electric fuel pump in the center area behind the flo...
By Ken Daugherty
I am illustrating a tool to set the A/B fuel pump diaphragm in the neutral position and tool to set the diaphragm and to remove the little clip from the C/912 fuel pump.
'A-B spacer block' shows the small wooden block that depresses the pump lever. The block is approx. 1/4" x 3/4" x 1 1/4".
'A-B pump tool' shows the block, 2, 30mm bolts and huts and a standard fuel pump block off plate.
'A-B' tool' shows the pump diaphragm in the neutral position, ready for final assy of the cover. (the diaphragm is this picture is a used one for illustration purposes only)
'C-912 pump tool' the component parts. A piece of sheet metal, ~16 ga., 1" x 5 1/2", A piece of conduit, ~7/8" x 1 3/8" long and 4 bolts, 2, 45mm and 2, 75mm' and 2 hex nuts.
'C-912 clip tool' This holds the diaphragm in placed so the clip spring can be compressed and the clip removed.
'C-912 diaphragm set tool' To set the diaphragm in the neutral position so the top cover can be properly fi...
By Cliff Murray
If you are having engine popping problems in a car that has been modified to use an electric fuel pump exclusively (no mechanical pump), first try locating your pressure regulator close to the carbs, and if that does not work then change to a rotary vane type pump if you have been using a pulse type. Here's my story:
After having no luck tuning my 1883 with Solexes bored to 44mm/35.5mm for street use, I switched to Weber 44IDFs. Better but not great and the inconsistency of operation continued. Repeated ignition diagnosis and parts swapping bore no solution. Every jet combo you can think of without any improvement. Popping from the carbs (lean) and popping from the exhaust (rich) could occur at any time but never during wide open throttle. Sometimes I made a change and the car would run well (success?) only to have it revert to popping again.
During this ordeal I had a Pierburg 6 volt pump fail and that was replaced by the supplier by an Airtex 6 vo...
Compiled by Mike Simmons, contributors listed below
Q: How do you restore an old gas tank? The gas has been sitting for 10 years....
LeicaLarry wrote, I cleaned mine out by flushing it with water. You might try breaking up the varnish with gasoline first. I then used a coating for the tank, Stoddard has it, or check Hirsh in New Jersey, make sure the over flo tubes are clear, use a wire as these releave pressure from the tank. If you wish you can wire brush off the rust and paint the area with a decent protective paint. If there are holes, you can solder them, or tin the area. Make sure all the fumes are out before you apply any heat. Washing with a garden hose for an hour, and then using a shop vac in the blower position for another hour will dry it.
Chris Lonie wrote, I cleaned mine with b-12 and then took it to a radiator shop for an acid flush. They wanted to puncture it to drain it and then reweld it. I said no way and just ...
Edited by Barry Lee Brisco based on contributions by Rick Dill, Christian Gates, David Jones, Charles Navarro, and Eric Nichols
In some parts of the country you are increasingly likely to have to run your 356 on gasoline with 10% added ethanol (E10) or as little as 5%. This is commonly known as "gasahol". (The up to 85% ethanol blend, E85, is uncommon and requires vehicles be specifically designed for that purpose. The few gas pumps offering this are prominently labeled.) It is reasonable to wonder if using this mixture in a 50-year old car that was not designed for it is going to cause problems. Leaving the political and energy cost/balance considerations aside, the comments below should help you make an informed decision.
More water in your gas tank?: Unlike modern cars that get driven regularly, many 356 owners may not drive their car for months at a time. David Jones writes, "Ethanol and alcohol fuels are hygroscopic [water absorbing] which is good and bad. Water wil...
By Steve Douglas, David Jones, Alan Klingen, and Pat Tobin
Editor: "Back in the day", when our cars were new, all American gas was leaded, and the oil companies touted its benefits, such as reduced engine valve wear. Then we all woke up to the fact that lead was a toxic substance and one way to reduce human exposure was to get it out of gasoline! But don't our vintage engines still need leaded, high octane gasoline? In short: NO. Here's why.
Steve Douglas, A coupe original owner: Lead will keep the valve seats from wearing out, but only on engines that don't have hardened seats. 356s have aluminum heads and so have steel seats that are already hardened. Old American engines with cast iron heads that did not have pressed in seats need lead to cushion the valves, keeping wear down. I don't think any 356 needs leaded gas nor any additive, just run the best grade of gas you can, adjust the valves regularly, keep the mixture a little rich and timing advance conservative....