Solex Vs. S cams 20L ?

[Fritz A. Ficke]

The PO had the cams replaced on my otherwise stock 1967 911S to a "Solex" profile by web cam in a effort to pass Az. emmisions. I know #'s are not everthing but I would like to know how much hp I am giving up running these.

The car is still a lot of fun to drive

[john_cramer]

Well, I think the answer is about 20 horsepower, but probably not much in terms of low-end acceleration.

The "Solex" profile is the same as the early "E" cam.

The 911 originally came with Solex carburetors and somewhat restrictive heat exchangers. The Solex carbs had an incurable flat spot and were replaced by 40IDA webers in February, 1966. When Porsche developed the 901/02 "S" engine, they also developed a better set of heat exchangers. When these heat exchangers were added to the Solex-cam/Webers engine (901/05) the output was around 140HP, which was too close, for marketing purposes, to the 160 HP output of the "S." Hence, the cam profile was changed to the "L" and restrictor rings added in the heat exchangers to detune the "L" to 130 HP.

Now, your "S" has higher compression pistons, so you might be making a little more power. But basically, you've got a 2.0 with solex cams and modern heat exchangers, so I'm guessing you're making around 140HP.

The "E" cams will give you better torque down low where a street engine lives. Unless you are a stickler for originality, I wouldn't tear the engine down to change them back. I really enjoy my "E" on the track . . . except at the end of the straights where above about 6300 rpm it doesn't make more power, just more noise. . .

[John Fusco]

That's the same set up as my car - Webers with the early cams only with 2.2 E p/c's
The low end is fantastic, the car just POUNCES !

John

[Richard]

The Solex cams are actually in between an early E and S cam in terms of duration and lift. The Solex cam is a noticably hotter cam than an E cam and actually not far from an S cam. You will notice a significant increase in bottem end torque with the Solex cams vs. S cams without giving up much in the top end. I have a 2.2S which the PO rebuilt with Solex cams and the car pulls strongly up to about 7,000. I have a 2.4S with S cams and the big difference I notice is that with the S cams there is a little less bottem end but at about 4500-5000 RPM the S cams explode and really put you back in the seat. The solex cams don't do that but offer a smoother, more linear power band. Personally the S cams are more fun to drive. Solex cams are probably a better all around cam for general use. I prefer the S cams in an S car because it's a major part of the character of the early S driving experience but the Solex cams in my 2.2L S perform so well that I'm not hurrying to change them. One additional item is that you say you have a "Solex grind" by someone like Webcam. You should check their specs against the factory S and Solex cam specs...then you'll really be able to compare them. Aftermarket cams can be very good and the more modern aftermarket cams can produce more torque or horsepower than stock cams so I'd check with the manufacturer. They can probably tell you how their cams compare with factory cams based on real life dyno testing.

[John Fusco]

The 69 E (901/09) cams have the same timing as the early cams;

52/62/64/44

[John Fusco]

That timing is from Excellence;
I notice that in the Perf. Handbook the timing is listed as :

901/01(solex) and 901/05 - 29/39/39/19

901/09 (69 E ) - ditto

John

[Fritz A. Ficke]

I am grateful for the help, I feel I must tell more, I had to disassamble the engine to replace the intermedate shaft alum. gear. While inspecting the cams I noticed the "Webcam" stamped on the end. Then I decided to look closer at the records I got with the car. The engine just had (6,000 miles ago) a complete top end rebuild by the PO, new valves,guides,rockers, rocker shafts,etc. and regrund and hardend cams "solex grind" was all on the recipt I got with the car, and the cams look perfect ,he had been charged $600.00 for these bad boys and now I feel beside the hp loss there is the "soul" of the 's' will be missing If I put them back in. But they are virtually new and I still have to pass emmisions (one time waver) and alot of people enjoy them ,I did. Then there is Richards words haunting from this post and another one where he talks about the "charactor of the S" and "explosing of power" and I am really torn, right now I am waiting on some machine work from Comp. Engineering, so I guess that means I have alot of time to think about it

[John Fusco]

Do you know anyone that might let you try their S ?

I am fast learing the biggest danger with these cars is to follow the siren song of never being satisfied with what you have in order to make it just a bit more "perfect"
If you got a lot of money go for it - or sell and buy an S - or just buy another.
The "lowliest" of these cars has more soul than alot of people I know.

Best of luck ;

John

[Fritz A. Ficke]

the biggest danger with these cars is to follow the siren song of never being satisfied with what you have in order to make it just a bit more "perfect"

truer words were never spoken, I am unfournetaly learning this first hand but I am trying to slow down and having to $$

[gruen911]

Wait a second. There is no no way that you are losing 20hp due to the solex vs S cams on the early 2.0 models. Besides the significantly higher compression pistons (9.8:1 versus 9.1:1), the 911S heads also had larger valves (42i/38e versus 39i/35e) and much bigger ports (the S had 36 intakes and the normale had 30) for air flow and a larger carb set-up for more fuel flow. All of these things collectively resulted in the extra 30 hp over the 67 911 normale model. The difference in cams did not account for 20hp. Maybe 5hp. If you could get 20 hp just from switching cams, we would all have an order into Webcam right now....