I have an Edelbrock carter AFB on my L69. I believe it is the 750cfm model. It doesn't have a choke. Is this why the car is a bitch to cold start? It's embarrassing. I have .101 primary and .100 secondary jets right now. I'm running the biggest (leanest) rod possible (forget the size offhand) and although my mixture smells pretty good (not horribly lean or rich), I'm still rich I think. WOT problems: From a stand still, if I floor it (even rolling into the throttle) I bog. If I really push it the car will die. If I let up, then mash it the car will run pretty well until about 4500 rpms, then start popping out the exhaust and high rpm power will drop. This is killing me with my heads and RPM intake. My motor revs to 6000 rpm stock and I want to be making power up to there! What exactly do springs do? I have learned everything by experimentation so far ... I'm using pink (7" mercury) springs right now. I have from 3" mercury to 8" mercury. The accelerator pump is in the middle hole. Any ideas? I have it running decently right now, part throttle acceleration is quite good and my gas mileage has been pretty good as well, but I can't do a burnout (it'll die) and I almost got beat by a fourth gen v6 car because my high RPM power bites *** ! Thanks!

First thing is clean all the air-bleeds in the carb. If the high RPM problem is still there then I need some more info.
*what is your fuel pressure at the carb during WOT?

*what is your initial and total timing numbers (ignore vacuum advance).

*what intake, carb-spacer, and camshaft do you run?

here is a procedure for tuning the bog out of the carb. You may have seen this on another post (I'm C&P).


*You do not clear up bogs & stumbles by jetting the carb up. You change jets to change your A/F ratio at full throttle. Stumbling and bogging is caused from the transition to full throttle metering.

*The very first thing you do is to check how you are driving. Do you slam the pedal quickly to the floor? if so then this is wrong. A carburetor does its job much better when you roll the throttle smoothly, not in a stabbing action.

*Next you work with the accelerator pump-shot circuit on the carb. If you already have the lever in the top hole (closest to the plunger), then the next step is to go to a bigger pump nozzle (number printed on top of nozzle). You remove the air-horn and replace the nozzle with a larger one. I run a #45 or #46 on my 750.

*The next step is to try stiffer springs under your metering rods.

*The next step would be to increase the accelerator pump-shot stroke length (a custom mod). You can drill another hole in the bottom lever and straighten the rod slightly to increase the ratio of the pump. Then you must clearance the top of the air-horn around the plunger so the lever does not hit the carb.

*The next step would be to go richer (smaller) on the power-step of your metering rods (the tips).

You shouldn't have to go past these steps. These steps already assume that you have a good initial timing (15 to 20 degrees) and an aggressive timing curve. It also assumes that you have no vacuum leaks or internal engine problems like an over-tight rocker or cracked valve.
As a last resort I might try putting a 1" 4-hole spacer under the carb to increase low-rpm signal.

I will check my timing.

Can you explain the exact function of springs?

and by stiffer that means lower numbers of mercury right?

and the bog is the least of my worries. I need to fix my WOT (esp. high RPM) problem. You agree with me that I'm too rich, right?

I was thinking of jetting down a bit. Like .98 primaries and .95 secondaries and raising the float level a bit.

Ok i have a 600 cfm carb, not 750. My apologies.

1405 Edelbrock.

stiffer springs are for higher vacuum numbers.
They complete the transition between the idle circuit and full primary booster operation according to engine load (vacuum).