Need help. My father recently passed away and left me with his pride a joy, a 1970 Mustang Mach 1, 351C. Thankfully he wrote EVERYTHING down on little pieces of paper so I have been able to gather information about the car. I am really a rookie when it comes to understanding all the bells and whistles but I am learning from others and watching ALOT of youtube videos. Thankyou to all the mechanics out there posting to youtube, much appreciated. My dad loved to rebuild holley carburetors. In doing so, he has written down, numerous times, what I think are jet values? Can anyone help me understand what it means. Here are some examples;

750VAC
71-75 70-74
4 4
146 144

Holley 650
69-73
4
142

I would greatly apprecaite someone help me understand what the numbers mean?

Thanks,
Eric

 

I'm guessing the second is a Holley 650 CFM carb and the 69 - 73 is the jet sizes. I'm assuming the 750 is a 750 cfm carb with the jet sizes but I'm not sure what the other numbers are.

 

Thanks for the reply. I found a Holley Carb that my father rebuilt. I finally figured out what he is doing. I agree with you. CFMs and jet sizes. What he is doing is subtracting the jet sizes, and then he is also adding them together. Those are the other two values he was writing down under the jet sizes. Do those values mean something?

 

Maybe the accelerator pump? I don't really know a tonne about carburetors (only ever owned one carb'd car). Holley has a bunch of info on their website, maybe this will help you out?

https://www.holley.com/blog/post/acc...y_carburetors/