Text and photos by Ron LaDow, Precision Matters
With very few exceptions, Zeniths tolerate all sorts of strange jetting and adjustments and still work OK. They work far better than OK if you spend some time to tune and optimize them. To tune them, you'll need:
A good tool set
A synchronizing tool
Some method of measuring the accelerator pump volume (more later)
Base/manifold gaskets (if you want to remove them for work)
32NDIX carb data reference (factory or aftermarket manual)
Buy three gasket kits for two carbs; when one washer goes missing, you won't need to wait until next weekend to complete the job, and spares will come in handy one day or another. For similar reasons, do not throw out any sealing/crush washers you remove while working on the carbs.
For good reason, carb tuning is the last task in a standard tune-up. It is impossible to tune carburetors if any other portion of the engine is damaged or out of t...
By Harry Bieker
Introduction & Requirements
Solex's are easy to adjust when compared to other Porsche induction systems. But they are much harder to adjust than American two barrel carburetors. It takes a certain feel.
Before attempting to adjust the carbs, the following must be correct:
the engine must have correct cam and ignition timing
the valves must be adjusted properly
the points, plugs, distributor cap and ignition wires should be in like new condition
the distributor must be mechanical advance
the compression difference between cylinders should not exceed 20 PSI
an engine compartment fuel filter should be in place
Note: Red type denotes components most commonly used in adjusting carbs
1 - Retaining screw 2 - Passage where high speed mixture enters air stream 3 - Needle & seat (after market shown, original has a spring loaded ball end) 4 - Fuel inlet banjo bolt (hollow bolt) 5 - Cover 7 - Injection...
By Jeff Stevens
I have been messing with these carbs on my car for about 2 years now. I probably would have been happy if I were most other people, but being an engineer, I had to fool with them to get better results. I have tried many combinations of venturis (28 and 32), jets (115-145), idle jets (50-65) emulsion tubes (F11, F7, F3) and air correctors (165-225).
My car is a 62 S90 with a 86A webcam (290 duration), Crane HI-6 ignition and pertronix ignit0r in an .050 dist. The following are some of my observations.
Dump the F11 tubes. No matter how many times I went back to them or with the combinations I tried them with, the car always felt like the brakes were partially on. The F3's are identical to the F11's except the body diameter is smaller. I believe they are just not a good choice for the application. They also tended to shift the mixture very rich. The F7's are the way to go. As one other list member...
Text and photos by Ken Daugherty
My method eliminates the floppy rubber hoses, ugly clamps and twist ties I often see with Weber carburetor installations.
I use NAPA steel tubing, pn 813-1235 (5/16" x 60"), forming one piece to fit behind and up under the lip on the fan housing (photos #1, #2, #3 below). I braze it in place. Note how the ends are positioned so the rubber hose will follow neatly around to the carburetor fittings.
If you don't want to braze the tube to the fan housing, you can fabricate clips, braze the clips to the tubing and then mount the clips to the fan housing with pop rivets. The photos below show the brazed crossover installation.
Next I fabricate a new line from the fuel pump to the carburetor fitting (photo #4).
On the driver side carburetor you will need to add an extra 'fuel inlet pipe' from Pierce Manifolds, pn 10525.023, phone (408) 842-6673 (photo #5).
The fuel hose I use is the common cloth wrapped 356 hose available from our vendors ...
By Ron LaDow
First published 356 Registry Magazine, Vol. 28, No. 6 Available in PDF format at www.precisionmatters.biz
Clean oil helps engines live a long and enjoyable (for us) life. Most all of us want our engines to last as long as possible. As pointed out in the article Stock Oil Filtration Effectiveness (Vol 28-4, Nov/Dec 2004), in stock form, "92% of the pump output, oil and dirt, go right to the various engine bearing surfaces". The stock 356 oil filtration system was very good in the 1950s, but engine life can be greatly improved without ruining your car's originality by fitting a full-flow oil filter. There are various designs and methods available which will provide full oil filtration to your engine, and they all have advantages and disadvantages. As a 356 owner, you probably have more options than any other vintage car owner.
Breaking the Circuit
Figure 1 – The bypass oil system. The plunger (A) would cover the main oil galley (3) during warm operation.
By David Jones
Overall view of lines for full flow system. Engine out of car in this picture. Here's how to plumb a full flow filter while retaining the mechanical tach (for those with electric tachs, there are other options). What is described and shown here only works for late "A" , "B" and "C" cases. Earlier cases would have to be tapped at a different point for the oil to filter because of different internal plumbing of the 3rd piece. Placement of the oil filter is mostly a personal choice. I have seen them out in the wheel well and on the shroud. No matter where it goes it will need one line to pass through the ductwork somewhere. I personally favor putting it in the engine compartment off to the left in the rear corner on a bracket. High enough to be able to remove it in an upright position so one can fill it with oil before replacing it and so as not to spill more than necessary when removing. I also favor using the filter that is compatible with the VW Rabb...
By Ron LaDow Special thanks for contributions by Alan Klingen of The Stable and Neil Fennessey, Ph.D.
First published 356 Registry Magazine, Vol 28. No. 4, Nov/Dec 2004
Modern engine design, lubrication and filtration systems provide amazing engine life and no sacrifice in performance; that is a development of the last 10 years or so. We've got the stock 356 engine design and the lube system is fine, but the filtration system leaves a lot to be desired and can be improved. Several shops and parts vendors (I own one) offer modern oil filtration.
Along about mid-20th century, engine speeds were increasing, bearing clearances were dropping to about .0013 per inch of bearing diameter, oil pumps were becoming well-developed and the engine designers saw that providing pressurized oil directly to the bearings drastically improved engine life. But to be effective under vehicle accelerations, and to keep the height of the engine low enough for modern cars, the pump pickups we...
Text by Rainer Cooney, Ken Daugherty, Alan Klingen, Ron LaDow
[Editor: After 50 years or more, 356 sump plates often leak. Here is a range of solutions to the problem from some of the veterans on 356Talk, as posted in November, 2008.]
Alan Klingen: Over the years the plate develops waves on the sealing surface from the nuts pulling it down. When the plate is off I lay it on a flat steel surface, such as an anvil, with the inside surface up and hit the stud holes to flatten them back down. You should also check the center copper rivet to see if has become loose. If you need to use a sealant use a non-drying one that be cleaned off at the next sump service.
Ken Daugherty: We 'flatten' sump plates by turning them upside down of an anvil, placing the ball end of a medium size ball peen hammer in the stud hole and carefully smacking the hammer with another hammer. This reforms the dimple caused by repeated tightening over the years. Caution, do wear safety glasses in case ...
By Barry Lee Brisco
The 356 engine is often described as "air-cooled", but a more accurate phrase would be "oil-cooled". After all, cars with radiators are "water-cooled" even though ultimately that water is cooled by the air.
With that in mind, it's easy to understand why 356 owners are concerned about their oil temperatures during hard running on hot days. If the oil gets too hot, engine damage can occur. But how hot is "too hot"?
Starting in 1950 (Ludvigsen, Excellence Was Expected) or 1951 (Johnson, Authenticity Guide) an oil temperature gauge was standard equipment. Up until mid-1957, the various gauge types over the years — first MotoMeter, then Stork, and finally VDO — had numbered scales that ended at 250F / 121C (MotoMeter, shown at right) or 280F / 138C (Stork, shown below right). At around the time of the T1 / T2 change in mid-1957 the numbered temperature scale used in the VDO "combi" gauge—oil temp and fuel level—was dropped and a simpler scale was use...
By Joe Leoni
If you think your oil temperature gauge is not giving you an accurate reading, most likely either the oil temperature gauge or sender has failed. However, there is a third case where the sender and gauge are not compatible. The indication would be that the oil temperature shows hot with a cold engine, then the temperature decreases as the engine warms. [Editor: Brad Ripley emphasizes that currently available VDO senders will not work with an original gauge. New senders from Porsche (made by Beru) that will work look different and cost plenty.]
First, some background on the sender location in the engine compartment. In mid 50's and later cars, it is located just behind the distributor. In earlier cars it's hidden behind the fan shroud. Brad Ripley writes: "On late 2-piece case engines, the sender is threaded in the engine case above the flywheel. On early 3-piece case engines, the sender is threaded in the case at the lower left corner. Starting with ...