Don't have a tach yet inorder to give specific RPM range but, my 67 belve with a 440 loses power in the higher rpm range. Idles well (for the cam thats in it) but when i stomp all the way to the floor it just stutters and seems to lose power... does the same thing when i slowly let the RPM's rise. It does it in all gears... when I am slowly running it up it regains power when i shift to the next gear and the RPMS drop... The engine kind of sounds like what a well built drag car does when its sitting on the rev limiter at the tree... just like it cant run any higher. Any ideas what to check? I just got the motor back in after its been out almost a year with oil pressure issues. dont know if thats relevant but just giving back story. thats about all i can think of... other than it has gobs of power and torque in the low end but practically falls flat in the top end. Any help would be great... thanks!

 

worn valve springs making the valves float? or maybe a spark issue

 

These are good points.

Or maybe the carb is running out of fuel?

I had a fuel pump push rod go bad on me once on a 383 Magnum. I replaced the rod and it was a done deal.

Then on another 383, I had the cam lobe for the fuel pump push rod go flat and I ended up installing an electric fuel pump.

 

I think 66SportFury is onto something with the valves floating.

 

i would look into what Silverick was starting at first just for the sake of being easier. fuel pump/pressure/cleaning the jets on the carb.... i had that a little bit last summer and i took my carb off and cleaned EVERYTHING and it seemed to work way better! also where is your timing set?

 

I just have the timing set by "ear" for now... since I just got the engine back in and running. I am hoping to get a chance to actually set the timing today or tomorrow. Any suggestions on where I should set it? I found some thing online once for the base setting for a mopar performance electronic ignition but can no longer find it. thanks,
Dave

 

Floating valves...tell us about your cam lift and valve springs you used...do you run a 3/8" pickup and fuel line all the way to the carb...could be running out of gas....I have all my timing in at 2600 rpm...35 degrees total....15 initial and then a 20 degree bushing in the distributor...Eric

heres how mine did on the second run...some noise was coming from the A/C compressor...

http://www.youtube.com/watch?v=JlxbhORbobE

 

the stumble makes me think ignition
i head something similar happen to my car
the ignition box was bad (or so i thought)
the rev limiter wouldnt let the car get past 2000 rpm
around those rpms, the car would just jerk and shake
turned out to be a mis-wired harness
just flipped around some wires and it ran fine

 

Yep could be that also...I installed a new summit/msd box on my buddies 70 Charger with a 520 stroker...it would cut out like it was hitting the rev limiter....happened to be crappy spark plug wires...we put some big taylor wires on it and that fixed the problem...some of his wires were in the 1.5 K range...I believe heat damage was the issue...I had one bad wire on my 340 roller motor and I could see sparks jump from the neg to pos terminal on the coil..

 

What is a good range for plug wire resistance?