383 Stumbles @ high RPM

[Ron Swampson]

Posting this for a friend.......

My buddy has a 68 383 newport and has done a lot of work in the last couple weeks. New fuel tank, fuel pump, fuel filter, 750 edelbrock carb and aluminum intake. 383 runs good but at higher rpm's the car seems to choke. as if its not getting enough fuel to supply the cylinders. The car had a stock intake and 2 barrel carb and he says the new add-ons have helped a lot, but the underlying condition still remains.

Any suggestions?

 

[Big_John]

Check fuel pump volume first. Even though it's a new pump, you could have a worn push rod... or a bad new pump.

Next, I would check float level. Again... New carb, but there's nothing that says the level is still correct after shipping etc.

 

[commando1]

Is he running points in that thing.
I don't know why but a vision of floating points flashed in front of me.

 

[rumpfox]

me too on the points floating. pull a plug to see if it's running lean. if plug looks like you've hit it with a tourch it's running lean. if light brown it's getting plenty of fuel

 

[70bigblockdodge]

How much throttle? If he is in it pretty far or to the floor I would blame fuel supply check the rod as mentioned. If just pedaling it most likely a ignition problem.

 

[heyoldguy]

Did it "choke" before at "high rpms" with the 2-bbl?

What is "high rpm"?

Really now, it is an original 2-bbl engine, probably with stock heads and valve springs and stock exhaust. How much difference do you think the manifold and carburetor will make?

And a 750 on a stock 383?

What elevation? Does it still have the stock 750 jets?