Weber jetting resources

[Fairlady5150]

Hello, hope everyone is doing well. Just wanted to pass along a great resource for jetting and tweaking your Weber carbs. Follow this link https://www.carbparts.eu/calc/ to a jetting calculator tool for Webers (many thanks to Sid Raper for forwarding this!). Super easy to use, just enter displacement, # of cylinders and carbs, and top power RPM, then select either 'calculate for flexibility' or 'calculate for power'. On the next page you will be able to select the choke tubes that you have, or you can change this to see the impact of going with larger or smaller choke tubes. Then you are given the jets needed to achieve the desired result.

While my new Webers, which were installed about 1.5 years ago, were an improvement over the SU's on the car, I felt like there was more performance not being utilized. So I've been doing a lot of research on DCOE's lately because the Weber conversion that Redline Automotive sells, while an excellent product, is packaged somewhat 'generically'. The jets that the carbs in this kit come with are a good baseline in general for all four cylinder engines, but some individual tuning is required to get the most from your setup (don't be intimidated by this, as re-jetting a Weber is remarkably simple, as shown in the additional links below). Apparently the only difference between 'kits' is the intake manifold. One example of this generic setup is the emulsion tube. The carbs come shipped with an F11 tube, but the F16 is far better for the 1600 or 2000 engine.

So the calculator linked above was very helpful. I calculated for power, then ordered the parts from Carbs Unlimited. Re-jetted last night and took it for a ride. Totally transformed the car, and the 3000-5000 rpm range is amazing. I'm still trying to get that big, stupid grin off my face. And since re-jetting Webers is so simple and can be done in 5-10 minutes, I'm thinking about ordering another set of jets set up for daily driving / flexibility.

For the benefit of anybody considering Webers, one mistake I made when installing the manifold and carbs was that I didn't realize how poor the machining quality of some of the Pierce manifolds was. I was under the impression that the setup was running very lean, when in actuality there was an intake leak. So I increased the idle jets several times to compensate, thinking I needed to go richer. I kept checking for an intake leak but couldn't find one. I finally found it on the bottom of the manifold in a nearly impossible place to reach. So I took both of the manifolds to a machine shop and had them flat and match the head surfaces, as well as the washer flats.

Don't let this discourage you from going with Webers, as they are an excellent product. Just know that some of the Pierce manifolds had some issues and may need to be machined first, which isn't a poor reflection on Weber.

Following are some other very helpful links. While some of these focus on disassembly and reassembly, there is a lot of good information on jetting selection, as well as how the various individual systems in a DCOE work. These are definitely worth your time if you have or are considering Weber carbs.





https://cnx.org/contents/oKbaEWQ3@2/Sel ... arburetors

Feel free to let me know if you have any questions!

Jason

[tjp]

Patiently waiting for Steve (D3S Shooter) to get his MOT paper work for the Ford (engine with the webers) so he can do the third part of this great video series.

[Fairlady5150]

Patiently waiting for Steve (D3S Shooter) to get his MOT paper work for the Ford (engine with the webers) so he can do the third part of this great video series.

tjp I agree. He's very informative. I'm trying to pinpoint his accent, Scottish maybe?

[tjp]

He's Dutch I believe.