Rochester Quadrajet Jet Size

[TED DIMON]

I am replacing the original Rochester Quadrajet Carb on my 1969  (Chevy 350 engine) with a Chinese knockoff.  What size jets would you recommend I use?

[Zedman]

Hi Ted- I'm very interested in doing the same and I will be keen to hear of your results.  I believe that most of these carbs come with a selection of jets and Metering Rods.

There is an excellent article by a well respected Rochester rebuilder by name of Lars Grimsrud here....  https://studebaker-info.org/Tech/Qjet/tuneaQjet.pdf     .   This is a must read IMHO- it is not just a matter of rejetting, but of the CFM range of the carb as well.  As I have a 305 engine, I only need a 600CFM range. Many of the carbs offered are 750's for much larger engines.  

Many years ago he took on a Chicom Quadrajet copy for a customer and went through it in great detail to get it running right. Metering Rod and Jet sizes were covered.  The whole topic was covered on line with heaps of photos. This is here.... https://www.corvetteforum.com/forums/c3-tech-performance/4523417-new-chinese-q-jet-inspected-evaluated-and-tested-the-complete-results.html

I'm pretty sure Alcohol blended fuels will more than likely require slightly larger jetting.

Good luck- 

 

 

Edited 17 hours ago by Zedman