Engine leans out under load?

[pettyblueucuda360]

Hi Guys,

My 360 in my barracuda is leaning out once I hit my torque converter at 3k. It has a AED 750 cfm carb with mechanical secondaries. The weird thing is tho I can rev it all I want in park/neutral with no problem with leaning out. I have a msd distributor with the timing set at 15 during idle and 36 total. The spring I have in the distributor allow it to hit total advance at around 2000rpm. The car idles fine around 800rpm. Does anyone have any idea what could be going wrong hear? Timing or carb issue?

Thanks in advance!

-Tom

[wilks3]

What fuel pressure do you have at wide open throttle?
Electric or mechanical fuel pump?
What size fuel line?
I'm not sure what you mean about leaning out at 3K RPM? Engine bogs?
Misfires?
Need to know more to start picking apart your problem.

[mhenesian]

Take one of the light springs out (leave the other one in), and replace with either the medium (blue) spring), or one heavy spring. This gives a relatively quick initial advance in the MSD distributor, followed by a slower rate to full advance at around ~2500 RPM. This should eliminate the "lean-out" feeling at large throttle openings. Easy to do, try it. I'd also advance the initial timing two degrees. With a 3000 RPM stall converter, we run one light spring with one heavy spring. On a four speed, one medium spring with a heavy spring,

Mark

[pettyblueucuda360]

Originally Posted by wilks3

What fuel pressure do you have at wide open throttle?
Electric or mechanical fuel pump?
What size fuel line?
I'm not sure what you mean about leaning out at 3K RPM? Engine bogs?
Misfires?
Need to know more to start picking apart your problem.

-Mechanical Fuel Pump.
-Stock fuel line up to pump then 8 AN to the carb.
-At 3k which is my stall speed the wide band gauge goes way lean and it bogs out. It pegs the guage at 22 and if I give it enough throttle it will die out.
-Doesn't seem like a misfire to me just seems like it aint getting enough fuel.
Weird thing is though I can rev it to 6k in neutral and it don't lean out.

[pettyblueucuda360]

Originally Posted by mhenesian

Take one of the light springs out (leave the other one in), and replace with either the medium (blue) spring), or one heavy spring. This gives a relatively quick initial advance in the MSD distributor, followed by a slower rate to full advance at around ~2500 RPM. This should eliminate the "lean-out" feeling at large throttle openings. Easy to do, try it. I'd also advance the initial timing two degrees. With a 3000 RPM stall converter, we run one light spring with one heavy spring. On a four speed, one medium spring with a heavy spring,

Mark

Thanks Mark I will definitely try that and let you know how that works out for me.

[mhenesian]

If the 750 DP is jetted in the range (say 73~75 primary, and 82 ~84 secondary w/o power valve), and the motor still feels lean (big bog, stall), then you're looking at a 50 CC accelerator pump kit for the rear bowl (Quickfuel QFT-21-101 $36.95 from Summit Racing), and maybe some larger rear pump shooters (0.035"). Even with a 3K RPM stall converter, you still need rear gearing to get out of the "hole", 3.55, 3.73's, etc...

Mark

[JVMopar]

It really sounds like you are running your float bowls dry. It's quite common for a person to rev and engine in neutral and not have the same fuel problem as when driving. I'd check my fuel pressure while driving. I'm thinking you have a restriction in the fuel system or an inadequate pump.

[pettyblueucuda360]

Originally Posted by mhenesian

If the 750 DP is jetted in the range (say 73~75 primary, and 82 ~84 secondary w/o power valve), and the motor still feels lean (big bog, stall), then you're looking at a 50 CC accelerator pump kit for the rear bowl (Quickfuel QFT-21-101 $36.95 from Summit Racing), and maybe some larger rear pump shooters (0.035"). Even with a 3K RPM stall converter, you still need rear gearing to get out of the "hole", 3.55, 3.73's, etc...

Mark

Ok guys I figured it out. When the carb came back from AED I installed it and put gas Teflon tape on the fuel lines. A piece of the Teflon tape came off clogging one of my primary jets. My question now is what kind of jets should I have in it? Right Now I have 78 in the primaries and 80 on the secondaries. WOT AFR's are 12.-13.0 so should I try to richin up the secondaries at all? Seems to be a little rich at part time throttle. Its in the 12 range mainly at part time.

I have a 360 small block La motor .60 over with weisco pistons should be a little over 9:1 compression, stock crank and rods, swirl port heads with mild port, mopar mechanical purple shaft cam .284 duration and .528 lift, mopar mechanical rockers, Pro products crosswind intake, Pro Products Balancer, Hooker Comp headers, Msd, Topped with an AED 750CFM Carb. Built 727 manual valve body trans with 3000 stall speed converter.

[crisser]

Are there power valves in the carb?

[JVMopar]

12 range at part throttle opperation is way rich. Remember 14.7 is stoic. and if I remember correctly max power is made at 13.3. If it were me I'd want to be closer to 14 during everything except WOT where I'd rather have around 13.5