Lean on transition

[77cruiser]

Just right off idle it's a bit lean.
Here's what I have.

carb 17082292
idle tube  .036
idle down .055
idle dis. port .094
idle bypass  .141
idle upper ab .068
idle lower ab  .075
main ab .086
pri jet  72
pri rod 50M

I ran it for a bit with a .059 down channel but seemed rich, so I went to the .055 now lean.
I'm thinking I should go to a .038-.039 idle tube.
Am I on the right path?

[Cliff Ruggles]

What application?....Cliff

[77cruiser]

385 sbc
9.7 comp.
240/240/ 108 solid flat tappet
AFR heads
Perf. RPM
Street cruiser
Auto trans
Idles with around 10" vac.

[Cliff Ruggles]

It's going to like bigger idle tubes, and maybe 1-2 jet sizes larger as well.....Cliff

[77cruiser]

I'll go up a couple thou. on the idle tubes.
The pri. jet seems OK I had 74 in it but had to have the APT bottomed & I felt it was still a bit rich. Now I'm at about 1 turn from bottom.

[Cliff Ruggles]

What size are the main airbleeds?

Float level?

Fuel pressure?

Fuel inlet seat diameter?.......Cliff

[77cruiser]

What size are the main airbleeds?  .086

Float level? 5/16

Fuel pressure? 6

Fuel inlet seat diameter? .13

[Cliff Ruggles]

That all looks good, what metering rod on the primary side?

Do you have a PP spring in place for the low vacuum at idle?.....Cliff

[77cruiser]

50M rod
Yes the spring is in, haven't checked when it comes in though. Pretty sure I have the stock spring.

[Cliff Ruggles]

That cam requires a low tension PP spring.

72 jets are lean for that carb with 50M metering rods.  We run larger jets in those for engines set up like yours.....Cliff

[77cruiser]

May have discovered the problem.  It would only happen right off idle as the ported vac. ported became uncovered, it has the delay port above it & until the port is below the throttle plate it would act as a vacuum leak. So I plugged the delay hole but haven't tested yet.