I am considering changing the jet sizes on my 750 double pumper as the A/F is running 11.6. I would like to get it to 12.7. How do I do this? Or is there a better way to change the A/F ratio?

Assuming everything else is working well (no bogs, stumbles, other problems), remove the front fuel bowel (watch out for the gas in the bowl, it will flow everywhere. Best to drain bowl by removing lower bowl screw and catching the gas in something). Next is the metering block. The jets are screwed into this block. remove the jets (don't mix them up) and check their size (stamped on the sides). Go up 2 sizes at a time until you reach your desired ratio.

Just purchased a 750 Holley that has been re-built, flowed,etc for drag racing.According to the specs it has #72 jets in the rear and #80 jets in the front.A/F is said to be 12.7:1 or thereabouts.The tuning instructions adressed chaging jet sizes and said if you change the front by 2 sizes the rears should also change by 2 sizes. Hope this helps. If you need any info off the spec sheet, let me know.I think it even has the squirter size. :D

Thanks for the info. Any extra data is much appreciated. Hopefully this weekend I can pull the carb and see what is inside.

Guy

Will try to remember to bring the sheet home tomorrow so I can post the remaining data.I know that they have a web site and I think it is:
AEDPerformance.com.Not sure what info is on the site. ;)

The jet sizes should be switched in my first post.The primaries are 72 and the secondaries are 80.The power valve is 4.5, the PVRC is .055, the high speed bleed is.031 for the primary and .025 on the secondary.The idle bleed is.070 for both and the idle restriction is .031 for primary and .033 for secondary.The squirter size is .031 for primary and .033 for secondary and the A/F is 12.8 for primary and 13.8 for secondary. As to what most of these numbers mean, I'm not sure. Looks "Greek" to me. :D

Thanks for the info. Some is greek to me but still learning..........