i have a demon 750 mech secondaries, with a t-56 tranny. AF guage shows me being pig rich through 1st and 2nd gear, then i shift into third, and it leans waaayyyyy out. When i shift into 4th, it goes rich again whats going on here?

jets are 76/85, 30cc pumps with 40/40 squirters. Car is rich at idle and cruise, and rich in 1st 2nd and 4th gear.

if i don't let off the gas on the 2-3 shift, it doesn't lean out as quickly, it takes about a second longer.

thoughts?

Eric

 

Could your fuel bowls be getting drained dry?
If you are just cruising along at the bottom of 3rd gear and then go to WOT does it lean out then too? or is it only after you've went through 1st & 2nd gears at WOT?

 

it only happens when i go through the gears. If i hit it in third only it's fine.

i had thought about maybe the bowls draining, but why would it go back full as soon as i shift?

Eric

 

When you shift the RPM's come down and it needs less fuel. Many people also let off the gas for a second between shifts & this gives it some time to catch up on filling the bowls.

You might want to check your fuel pressure while you're at WOT from the point the fuel line connects to the carb. You're pump might not be enough for your engine.

 

if i don't let off the gas on the 3-4 shift it will still go back rich though. Fuel pressure is at about 7.5psi at idle, no idea what it is under load. I"m using a Holley mech pump, can't remember the specs...

Eric

 

You've got a pretty healthy car. I bet it's just running out of fuel.
Things to check for are:
fuel pressure at WOT
bends/kinks in fuel line and overall size
clogged or too small fuel filter
fuel tank not vented well enough
fuel tank needs sump or baffles to prevent fuel slosh (common with manual transmissions)

I'd say your car is quick enough, and being a manual transmission, probably needs an upgrade to any one (or all) of the areas mentioned above.
My guess is that you probably are jetted too rich, but sounds like maybe the secondary jets get uncovered or a bowl goes empty on you once you get in 3rd. If your demon comes with secondary jet extensions (to prevent uncovering) then a bowl must be going dry.

Most of the quick cars that pulls like yours does uses electric pusher pumps instead of the mechanical puller that you have.
Anyway that's my input.