I recently installed a new Weber 48idf ever since the cars been sputtering it does it when I hold it at about 3k rpm’s it almost sounds like 2 step any ideas?

 

what jets are in there? carb isn't going to tune itself

link is to a paper written by a scientist on how to tune a weber, its really easy and it works https://www.rx7club.com/1st-gen-gene...paper-1145099/

 

Fairly common issue. I'm having difficulty finding the words at the moment but basically you are either too rich or too lean. With a weber carb, at least with a IDA, there are three "stages" idle, transition, and main. but two sets of jets to manage them. You have you idle jets and your main jets. The transition stage should progressively switch from idle to main and back smoothly. The trick is getting the combination of the two sets correct. And unfortunately, there are a ton of variables and not really a one size fits all approach to this.

For me I'm running (at least according to my documentation) :
Main 145 F3 170
Idle 120 60F10
Venturi 37

With the above I don't experience the sputter/bog/dead spot that most people mention. If you tried the same you'd likely have a wildly different experience because EVERYTHING matters. Exhaust, intake, ports, altitude, compression, timing, color of your car... Ok so maybe not the color but hopefully you understand. I have a wideband and used it to help me figure out jetting and while I don't experience the dead spot any more I'm still too rich in the area (while cruising) I just don't want to mess with it any more at present. Tomorrow may I'll unbury this again and try to get it perfect.

 

i went through a bunch of threads to try and correlate the main jet size to power. in theory the main jet size is kind of like injector size, only a certain amount of fuel can go through it
but it just didn't work. too many other variables....

 

ok thank you it’s also been cutting out when I get back on the gas but the car drives super smooth when higher in the rpm’s and it smokes pretty bad until I drive it for a bit, the smoke just smells like fuel I thought it was my ocrs but I’m not losing any oil and it doesn’t smell like oil at all

 

its streetported by the way idk if that helps

 

I had this issue for a while, I honestly think the new Biden-approved gas blend is causing shenanigans. Just run seafoam all the time..