I need some help. I put a all new 383 stroker in my 78 Blazer. 487 intake 508 exhaust Cam. I had a quadrajet and the 383 didnt like it so I put a Holley quad replica and the 383 runs ok, but wont idle right and isnt getting the best out of the engine. So I bought an Edelbrock performer series 750 w/elect choke. (Im 700ft above the mile high city of Denver). The Edelbrock runs good above 40MPH but not like an engine with 400HP should run. It starts cold and chugs on what seems like 5 cylinders till it warms. It will not idel right at all. Meaning, the idle changes by itself. It goes high and low and the motor will just die. At take off it almost dies then catches and goes. I had a local expert re-jet it and nothing changes. It has electronic ignition. My "expert" says I need a Holley street avenger?? I have had 2 carbs on the 383 and am thinking the edelbrock will work if it's tuned right. It runs ok, (not at all showing the power a 383 has) above 40MPH but when I come to a light I have to put it in N and feather the gas just to keep it from going low idle and die. If anyone has suggestion I appreciate it. ps. another friend of mine said a 750 is to large a carb for this elevation? I disagree with that one. Any thyoughts? Any ideas? Thanks

I have a 383 stroker in my camaro that is a little bit more powerful than yours is. I too have the Edelbrock 750 carb but mine has a manual choke (model 1407) I can tell you this. My engine does not like to run when its cold. The engine needs to have some heat in it for the fuel to become atomized so it can run on its own without using the choke/fast idle or manually giving it gas.

As far as idle changin by itself, I had that problem too. Thought it was a vacuum leak but it ended up being my timing. I was using very light advance springs in the distributor, and my advance stated to kick in at about 850 RPM. My idle speed at that time was just a tick over 900. It was one of those things where the engine would be idling, the rpm's would crest over 850, the advance springs would stretch open, ignition timing became more advanced, then the engine rpm would increase due to the ignition advance and rpm's would surge, then drop back down and so on. What I ended up doing was warming the car up to operating temperature, revving it up to 3000 RPM, and setting the total timing to 36 degrees of advance. Where she was at idle is where she stayed, and honestly she likes it there. I think I have 16-18 degrees of advance at idle, which is now a nice steady 750-800 RPM.

Most carb issues can be masked by timing so get that figured out first. Once you know that it is good, then move on to the carb. On a side note, not sure what kind of parts your stroker is running but the place that did my dyno tuning said I need a bigger carb. They are telling me that the 750 Eddy carb is too small for this engine, and they recommend an 850 Holley double pumper. They swear up and down that just by going to this carbo I will pick up another 10-15 rear wheel horsepower. And just so you know, the Eddy carb does have potential if you want to keep it: I am making 419HP and 430TQ @ the wheels with the Eddy 750 right now.

As far as nailing it from a dead stop and it wanting to die, yep had that problem too. Fuel pressure dropping below 3 PSI is the culprit. Check to see what kind of fuel pressure you have. Are you running a mechanical pump? If so make sure that there are NO RESTRICTIONS before the pump. I made that mistake too. Any filters need to be after the pump on the pressure side. Another cause of that hesitation condition could be due to when the secondaries open. The Eddy carb only has an accelrator pump for the primary circuit and not the secondaries. When you go full throttle, all the throttle plates open up, the accelerator pump squirts fuel for the primary side, but in order for the fuel to start flowing in the secondary side, air has to rush past the fuel tube to start the siphoning process. This is another reason why my dyno place is recommending the double pumper Holley cause it has accelerator pumps for both primary and secondary. Although I am not sure if it makes any difference for you becuase you are at such a high altitude. Hopefully you get it figured out. Good luck!!