Mechanical six pack idle circuits
i posted some of this over on for B bodies only but thought it may be of interest for some guys over here also as it seems a lot of the “A” body guys run the 4782 & 4783 direct connection or “hustle stuff” carbs. In my case I’m running a set on a 511 low deck with Indy SR heads and solid 260/266 @ .050 camshaft. I decided to run a 4412 “500 cfm” center instead of the anemic 4782 center. The issue I experienced was the unadjustabe outboard idle circuits just did not supply enough fuel at idle on my low vacuum big cube engine. My first “fix” is I went up .010 on the weep holes that supply the fuel. Unsatisfied with that I ended up adding full idle circuits as well as adjustable idle bleeds. While this was a bit involved, I’ve been able to really dial in the cabs to have excellent A/F readings at idle & cruise while maintains great drivability and WOT performance.
Tools needed;
Numbered drill bits
Small harbor freight drill press
Center punch
Some QFT/proform metering blocks ( I went without powervalves although you could add those too if desired).
For adjustable air bleeds
8/32 tap & 8/32 brass set screws
First step is identify where we need to add the circuits
The main body face is predrilled although it will need to be drilled slightly deeper
This will be where the idle circuit passes through to the base plate
Origional weep holes. I plugged these with brass tube and epoxy to kill them.
i posted some of this over on for B bodies only but thought it may be of interest for some guys over here also as it seems a lot of the “A” body guys run the 4782 & 4783 direct connection or “hustle stuff” carbs. In my case I’m running a set on a 511 low deck with Indy SR heads and solid 260/266 @ .050 camshaft. I decided to run a 4412 “500 cfm” center instead of the anemic 4782 center. The issue I experienced was the unadjustabe outboard idle circuits just did not supply enough fuel at idle on my low vacuum big cube engine. My first “fix” is I went up .010 on the weep holes that supply the fuel. Unsatisfied with that I ended up adding full idle circuits as well as adjustable idle bleeds. While this was a bit involved, I’ve been able to really dial in the cabs to have excellent A/F readings at idle & cruise while maintains great drivability and WOT performance.
Tools needed;
Numbered drill bits
Small harbor freight drill press
Center punch
Some QFT/proform metering blocks ( I went without powervalves although you could add those too if desired).
For adjustable air bleeds
8/32 tap & 8/32 brass set screws
First step is identify where we need to add the circuits
The main body face is predrilled although it will need to be drilled slightly deeper
This will be where the idle circuit passes through to the base plate
Origional weep holes. I plugged these with brass tube and epoxy to kill them.