engine dies, but only when punching it... please help!

[455 big block]

my 455 is mated with a TH350 (3 speed) and it dies any time i get around 70 MPH if i throttle hard. its hard to explain what it does- it kinda starts dying but reviving over and over until i let off the pedal and let it slow down... but i can go way past 70 on the highway as long as i accelerate slowly

i recently replaced the fuel pump with a high volume (130 GPH). this doesnt fix the problem, but engine seams to pick up faster when i let off the throttle.

im replacing the filter just in case, but i dont think thats the problem...

engine does not over heat, ive got a gauge i constantly watch, as well as the oil pressure.

parts im using: holly 4 barrel carb on edelbrock torker II manifold (heres a pic of what it looks like. excepting the fuel pump, which is replaced, and i re-did the entire wiring throughout the engine bay and dash)...

Photo10151252.jpg

[hoogiesngrinderz]

Specs on the Holley? Double pumper, vacuum or mechanical secondaries, etc.

I'm a bit confused as to what it does...does it bog/stumble or do the RPM's climb without the car accelerating?

[85z28kid]

When's was the carb last rebuilt? Maybe there's something in there blocking something.

Does it wanna die out from a dead stop if you hammer it?

[TylerT/AZ28]

sounds like carb problems in my opinion. maybe it needs a rebuild or retune becuase it sounds like its dumping

[1BADAIR]

Common with fuel injection when filter is plugged.
Either the filter is plugged, jets too small, ect.. It's running out of fuel

[2002Z4CSS]

Sounds like the carb secondary circuits are plugged up. Too bad you did not live closer, I could rebuild that carb.

[455 big block]

thanks for the thought so far- ill get all of them looked into!

but to answer a few question, i dont know much about the carb (was on the engine when i got it) only know its a holly duel feed. and no, it doesnt start to die off the line, but honestly i cant get the RPMs high enough at a dead stop or anywhere near it with how much torque i have

yes, it does seam like its running out of fuel (my mechanic took it out for a drive after we worked on it and thats what he said), thats why i got a higher volume fuel pump, helped a little, but didnt fix the problem... i told him on the phone, he said hes too busy to work on it, but it might have something to do with vacuum...

[TB2]

Sounds like you have a lean condition with the carb. Sounds like its just on the secondary curcuit. Carb needs to be tuned and/or rebuilt. May be as simple as a jet change on the secondaries. Without more info on the motor and carb, its possible the carb may be sized wrong for the motor. Also check to make sure that both the mechanical and vacuum advance are working properly.

[wasjo6431]

i can honestly say it sounds like a secondary issue. either its not opening or not dumping fuel. id suggest taking your cylinder 8 and 7 plugs out and take a look at them. also check 1 and 2 if its a vacuum secondary id check your vacuum lines if its mechanical id check to make sure with the air cleaner off the blades are opening and then id pull the secondary block off at least and take a look at it. it doesnt take long or much to rebuild a carb i just did mine last fall it was leaking. if you do rebuild it use the neoprene gasket kits from holley. But definately check that. also what size is the carb might not be getting enough air to the engine big blocks require big air. emagine yourself running adn trying to breath through a straw. you end up starving yourself of air.

[455 big block]

well- looked into it further.... carb is leaking at throttle (slightly), and the vacuum is set all the way in advance, even at idle. so when i throttle, nothing changes........

i need a rebuild...

thanks for the help

(p.s. anyone know of someone in/ near midland that does rebuilds? i can always try it myself for first time, but pro rebuilds sound a little more reliable xD )