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Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Thu Sep 14, 2017 5:41 am
by Armodilo
I have idles on order: 45, 50, 55, +, I also have mains and airs on order as well, in a variety of sizes as suggested.

I'll review all the suggestions and tips posted once they get here and go from there -- I'll dial in the idles first and then figure out my mains and air.

Ed: The carbs are 44's for sure, I did check that. How do you identify the venturi sizing, is it stamped somewhere like the jets?

Sorry for the silly questions, this is all brand new to me but it's making a lot of sense, thanks to you guys :)

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Thu Sep 14, 2017 6:10 am
by egrant5329
It should be stamped on the tapered edge of the venture. I would have to look but I think 44 IDFs come with 36 vents installed. That might be a little big for a 1915, but I think 30 or 32 would be what you want although I am not sure.
CB makes the 1915 engine as a standard option, really Pat should be tell what you should be jetted to. If he won't for some reason, surely someone on the SC has one and can tell you what they are jetted to as a good starting point.
Ed

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Thu Sep 14, 2017 7:22 am
by Armodilo
Thanks. I'll double check that too.

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Thu Sep 14, 2017 10:24 am
by egrant5329
If you are like me, figuring out stuff like the carbs is really the fun part of these cars (although frustrating). There have been a lot of people that fret over every detail and spend countless dollars and several years to get extremely nice cars and then turn around an sell them with 500 or 600 miles on them. They generally have the cars built for them. The ones who do the work themselves seem to be the ones who hang on to the cars.

2 books I found useful are:
Weber Carburetors by Pat Braden https://www.amazon.com/dp/0895863774/re ... 0895863775 It has some interesting jetting tables in the back
The Weber tech manual by Bob Tomlinson https://www.amazon.com/Weber-tech-manua ... B0006F1KBM
Another member, Rev, recommended John Passini
Weber Carburettors Tuning Tips and Techniques by John Passini https://www.amazon.com/Weber-Carburetto ... A4JWTPYZ8F I haven't read it, but will at some point. Admittedly the reviews don't look very encouraging.

Ed

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Thu Sep 14, 2017 11:25 am
by Armodilo
I am, that's part of the reason I acquired the Spyder. I'm a designer by trade, and love all things mechanical. The Porsche philosophy combines everything I'm passionate about and the Spyder is proposed to be my hobby / stress reliever -- in terms of maintenance/upgrades and learning as well as the fun of driving.

I bought and have read Bob's book twice now, as well as many online forums. I'll look into the other two -- thank you for the references.

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Thu Sep 14, 2017 4:29 pm
by egrant5329
My Passini book showed up today. I'll say one thing, the print is tiny (~8 font). You'll need a lighted magnifying reading tool to read it if you are over 40. #-o

Skimming through the book most of the diagrams and graphs are the same as the other books. Looking at a few key sections, like on the main/air corr., there does seem to be a little different explaination that gives insight to how the 2 interplay, but I don't think I would understand it or find it helpful without knowing what little I already know. It will take me a little while to read through it before I make up my mind, but it wouldn't the first book to turn to if I were trying to understand tuning the carbs.

The pic shows the tesxt compared to Tomlinson's book just as a comparison.
Ed

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Fri Sep 15, 2017 11:16 am
by SpyderMike
FWIW I always found these articles helpful:

http://www.aircooled.net/vw-parts-cat/v ... etor-tech/

Re: A few things: Distributor Curve / Jetting / Gas Smell

PostPosted: Fri Sep 15, 2017 11:56 am
by egrant5329
John Connelly at ACN is great! He has posted a lot on wideband tuning Webers on thesamba.com He has also been generous with his time helping me understand carb tuning and helped me setup my ignition MAP for my crank trigger setup.
Ed