I have a 4bbl intake on my 390, and an edelbrock 750/w manual choke on it. #1407. I can drive this truck just fine for the most part, it has good power while using the primary two barrels. (I think the ones always in use are the primaries?)
Anyways if i open all four up, pedal to the floor, but at about 45+ mph, the engine runs no problem, although it seems to drop rpm slightly once the 2nd two barrels are opened.

BUT, if I am shifting, like today example 2nd to 3rd, and floor it from the shift, it popped and died out, flooded. Happened to me twice today within an hour. the first time it flooded i'm not sure why it happened, but the second time was as stated above. Is the carb just too much and floods when floored like that? Anything I can do to help eliminate this? accelerator pump setting? If I have too i'll end up buying a 600 eventually, but stick with the 750 for now...

 

Check float height.

Check accel pump, may be larger than you need.

Have you checked basic jetting? How do the plugs look?

Power valve size?

 

Well it's along side a road a few miles away so i have to go back out and jump it cause the battery died while tryin to get it to start for about 10 minutes yesterday. Once i get it started and home, i'll take off the carb and check the float level, but that's the only thing i know how to check. I don't know how to check any of the other things you mentioned. Better to just take it to a carb shop?

 

Unless you want to learn how to do it, go to the "carb shop".

Is this a "double pumper" carb, with an accelerator pump in the secondaries also?

Is this an otherwise stock 390? Cam and headers?

You will be better off with a 600 if it's stock or close to stock.

 

It has the carb, intake and headers. It's getting gas, it has spark to all eight cylinders, and it just pops through the carb a few times. Just one accelerator pump. sometimes it catches a little bit, but won't turn over. I had the engine to 4k rpm right before this happened, but i don't think that should be too high to the extreme as the peak hp is made over that.

Checked the push rods and none are bent. I really think it's just too flooded and won't start. I need to get this back to my house, then i will take it to a shop, and have them tune it and adjust it done a few sizes. Will that work?

 

If it's jetted correctly, with the right accel pump and power valve, and the right spring for tipping in the secondaries, it will run ok. But that's still more carb than you need, so you may get a bit of a bog out of it when you floor it.

A stock 390 PU engine isn't going to go much over 4000 rpm, maybe 4500 before the valves float or it just won't flow any more air due to the cam.

 

I brought it to just under 4k. no more. should i be worried? there isn't any awkward noises so i don't think anything happened.

When i took out 4 spark plugs and heated them up with a torch and put them back in, it seemed to help it try and catch a little more. hopefully it's just flooded that bad.

 

I have a 428 cobra jet and it only uses a 735 cfm. However, it sounds like you have a carb problem. There are adjustments that are critical for the secondaries to open.

 

I just can't figure out why it wont fire. This happened yesterday yet it still wont start today just sputters barely a bit at the most. Not sure if the timing jumped or something cause this has never happened before. And it shouldmt be that hard to get started.

 

Grab a freind and hook up a timing lite as you turn it over. How is the spark at the coil? pull a plug hook up the plug wire are ya getting a good blue white spark? Check the simple stuff first.

 

yea once my friend can trailer it back to my house, i'll check the compression, the timing and go from there. There is spark at every plug as we checked each one doing the screw driver in the boot to a ground method.

Just puffs out of the carb every few times i try to crank it and some fire sometimes.

 

Well first off an Edelbrock carb has no power valve. The secondaries are are mechanical but the air valve controls the air flow thru the secondaries. If the air valve is set too loose the engine will fall on its face and possibly die when you mash the throttle. The best part about this carb is if the air valve is set properly it will only open the secondaries as far as the engine can handle. Oh this is not a compression or timing issue and people than don't understand carbs and how they work should stop giving advise.

 

Well once i get off work today, ill hopefully get it back to my house to work on it. I know how to take the top of the carb off and what not, but i have no idea what and where the air valve is. Any diagrams or something to show me that?

 

Before you do anything, go here:

Edelbrock.com - Tech Center - Carburetor Frequently Asked Questions

Download the owner's manual.

 

well first thing is i need to get it home. so im gonna go try and see if i can start it or not. i guess just hold down the gas pedal and spray a little starter fluid in it and see what happens.

I'll read through that stuff though, maybe even call them to explain exactly what happened.