Red dot Solexes

[1QuickS]

Solex factory service in the mid 1966 year by by factory mechanic & later Porsche dealer Wolfgang Rietzl were identified by red dot with check mark. Since Solexes developed erratic idle performance within a few thousand miles of running and repeat warranty tuning was a liability I assume the factory sent specialists to address these issues. Eventually the best course of action to solve the low speed running issues was to replace Solexes with Webers. Info and "survivor Solex" photo courtesy of Tom Bridgers.

I just finished a set of Solexes displaying remnants of the red dot (sans check mark) which I restored. It appears the modification at the time included re-sizing the OEM 1.00mm idle air bleed to be 0.90mm and possibly enlarging the 125 mains to be 130. Linkages would have been "tweeked" to remove clearances which lead to erratic idle performance.

First picture is of the jet carrier with "tuneable" idle air bleed jet installed. I maintained the 0.90mm idle air bleeds but revised so these are "tuneable".

Second picture shows project "as-received"; Solexes for cylinders #1 & #4 displayed the red dot.

Third picture is of "survivor Solex" with dot plus check which indicates service by Rietzl.

Fourth picture is of finished project.

[StephenAcworth]

Never knew that, Paul: very interesting details and superb work on your project... I cannot imagine the hours that took...

[gulf908]

Paul,

I strongly believe that the Solexes were given a bum rap in service due to insufficient development.
My take is that they were a better design concept than the Webers which were pressed into service at the last moment.
Those in the last pic look good enough to eat !
How did they go when fitted ?

Cheers
Dennis.

[718RSK]

Paul, Mine have yellow dots on them. Have you ever seen this before?

[Jon B]

Paul, Mine have yellow dots on them. Have you ever seen this before?

Here you go, Joris.
Don't say that I never do anything for you ;-)



Jon B.
Vista, CA

[718RSK]

Thanks Jon, Appreciated as always!!

[ejboyd5]

One now has to wonder how many Solexes will now have red or yellow dots added. Perhaps not within the Porsche fraternity, but among other makes . . . ?

[1QuickS]

My red dots will be dyno'd the week of 16Jan & I have been promised feedback. I am sending a jetting package for optimization. Car is slatred for a rally out of Reno at end of month & will be "enjoyed" by Warren Eads who might be known in the historic race world as a Sypder racer. I expect to be updated as to what he finds after living with it for a vigorous driving weekend.

As to bum wrap: From what I have seen there are plenty of design deficiencies in the throttle linkage setup & in the throttle shaft journals that when combined made these devilish to live with. Also, the twin mechanical Pierburg pump needed attention to prevent fuel starvation or flooding. The straight down (well, almost straight down since the end bores are actually inclined 5 degrees from vertical) bores are slightly more efficient than the inclined ones for the Webers. Webers actuate with one throttle shaft where the Solexes have three which means three times as many to keep adjusted. Porsche always used Webers on their race cars and Solex on production cars. When the Solexes began causing trouble, Porsche had already developed the Webers for the 906 program and were able to replace the Solexes quickly with a proven product. Another interesting tidbit is the first 906's (904s with the 901/20 engine) were tested at Monza in December of 1964; one car with 46IDA3C Webers & another with 44mm throttle bores in the Solex 40PIs. Webers were selected for the competition program.