Originally Posted by lg1969
What you get is lean backfire. Your 1st and 2nd gear may be fine, But it may bog on 3rd gear cause by large primary. Your intention on your 4X4 is to produce torque not RPM. Use a 600 to 650 CFM carburetor. 750 is too much. Also increase the advance weight on the dist.
Lean back fire is very possible but he has already went up a step on the mains so it should atleast be drivable. Maybe not making max power but running.
At this point need to read the plugs and see if its lean or rich.
750 should be ok for most apps. 600 650 may make a few ponies moe down low but the 750 should run ok.
Might just be plugs at this point not sure since the fuel pressure change helped. Cleaning the plug may sort it out.
If you have another edelbrock around that you can swap and try i say try it but most ppl dont have an extra hp carb laying around the garage. It is certainly possible to get a bad carb from the factory. Another user on the forum recently had that happen to him and holley replaced it for fre and it resolved the issue. Unfortunely most manufactures will at least want to run over a testing proceedure and try to get things smoothed out over the phone.
A call to edelbrock might not be a bad idea. They have good techs on hand usally that can go over the install and find any gottchas since they deal with the carb every day might be able to fix it faster than any other testing.