425 Performance and Carburetor questions/ HELP!

Sorry to hear of your loss Doc, I will keep her in my morning offerings. I will be going the q-jet route, A mod that was told to me was to open up the APT screw on the bottom?, not sure what this does. With the #7042240 800 cfm Q-jet what jets, hangers and metering rods should I do. My set up is a .030 425 with a isky cam 214 / 224 dur @.050 .469/.496 lift 110 LC ported polished heads, ported manis and intake with dual plane mod, recurved dizzy, dual 2.25 exhaust on a 3.23 rear posi with a 300 sp converter.

 

Thanks, Snake,,, and all you other guys.... it is good to have friends at times like these.....

Snake , sounds really good , the way you have your car set up..... like the Isky.... and the ddp mod :laugh: ....

 

loosening that APT screw up in the front of the baseplate allows you to fine-tune your cruise mix with a jewelers screwdriver. Screwing it in will lift your rods making cruise mix richer. screwing it out obviously lowers the rods and leans out cruise mix. Its the same effect as changing out smaller or bigger rods, but without removing the air horn, and its a bit more precise.


Trouble is, that screw is a real pain to loosen up. Take your time, use lots of heat and penetrating oil. DONT use a lot of torque on the screw or you will break off the screwdriver slot.

 

Thanks for explaining Ken, what rods, mains and hangers do you recommend for my set up.

 

Sorry to hear of your mom's passing, Doc. Glad that otherwise, you are OK.

 

Thanks John.....

 

Youll need to tune the carb on the fly ance you have it running to get the last hydrocarbon burnt and making power.

Unless you want to get into a full recalibration including tubes and channels and restricions, I would stay near the stock kets rods etc..

As a starting point I would probably leave the primary jets stock at 73, maybe run a 44B primary rod, put a richer secondary rod in there, like an AY or something. A hanger in the M range. And I would tune my primary pulloff to open in like a second and a half.

Make sure the throttle blades open a full 90degrees via the gas pedal.

You will likely need to adjust from there but its a decent start.