Help with sputtering issue
 

So I was out for a cruise today and the car ran great. I was on my way back and punched it down around 30 mile an hour and it spun a bit and then hit 2 and it gave a little shirp as normal. I went to do it again and as the RPM climbed it started to sputter so I shifted it into second and it still sputtered. It continued to sputter especially if I was on the gas hard. Any time there was a load put on the motor it would sputter. If I tried to speed up with too much effort it would fall on its face and then run pretty rough. I could cruise down the highway just fine but if I slowed down at a light or to turn it would sputter and once or twice it stalled. If I was cruising and let off the gas you could watch the RPMs go a bit erratic and you could feel the roughness in the motor. I can get rpm out of it while it’s in neutral, it does sputter a bit but will climb but as soon as I put it in gear it starts to stumble and will eventually stall. I am thinking that it’s a fuel issue. I changed the fuel filter and that didn’t help. Checked all my wires and checked for vacuum leaks and everything is OK. The carburetor is an Edelbrock 750 CFM. It is roughly 12 to 14 years old and has had no maintenance on it plus it sat for a bit on another motor before installing it on this one. I’m thinking that is my issue but I’m also wondering if my MSD box could be the problem. The motor is a Butler 467. Everything is brand new on it except the carburetor

you will need to do some more basic testing, fuel psi when it sputters, check ignition for full 12v to coil, can also use an ohm meter to test the coil, module & pick up coil in the distributor. if ignition check out ok & the fuel psi is good.... i would pitch that edelbrock carb, its not tuned to your engine specs & those carbs out of the box are set up more for a stockish small black chevy than a big 467 pontiac.

i would have a good carb shop build a mid to late 70s q-jet for it based on teh engines specs or use a holley that can be tuned a little easier.

My first idea is fuel related. Check pressure. Could be a clogged sock in the tank. Verify that the spark plugs are clean. A Q-Jet properly set up will run circles around the E-Brock carb.

I had a chance to look at it today. It wasn’t a fuel issue but my coil. It had partially failed I’m guessing or at least it had an issue. I replaced it and everything is back to normal. Thanks for the replies. They’re greatly appreciated. Nice to get out again before the weather changes.

good to hear you figured out the problem... but changing that edelbrock carb is still a good idea, it will run "ok" but you will see a big improvement in performance & how the engine idles & runs with a proper q-jet or even a holley tuned to the engines specs better than a stock old e-carb.