Sbc 350 falling on its face

[Sherrow74]

I have a 350 and turbo 400 setup in my 87. Its got a holley 600 and an hei distributor. It runs great until you hit 2500 rpms in third gear. Any other gear it fine but in third it falls on its face and won't do anything until you let off the throttle completely and it picks itself back up. I've replaced the distributor, fuel pump, and fuel filter. The only other thing is that it has a valvetrain tick to it. I havent got a chance to check it out with a vacuum gauge but other than that I'm stumped.

 

[legopnuematic]

How are the rubber fuel lines? A rubber line with holes in it before the pump will not leak fuel, but will suck in air causing starvation. Just a thought, fairly inexpensive to give it a try.

 

[Frankenchevy]

Check the float adjustment and that it is keeping enough fuel in the bowl.

Slight chance, but a possibility nevertheless

Edit: also ensure the distributor advance is correct. Doesn’t make sense that above 2500 in 1st and 2nd are fine. That’s why I’d suspect fuel. Takes more fuel to maintain a given rpm with higher speed and wind resistance.

 

[theblindchicken]

Sounds like either a fuel issue or a spark issue for sure. Have you checked the condition of your spark plugs and plug wires/boots? My truck burned quite a bit of oil and when the plugs got fouled enough, i'd have a massive stumble on the upshift from 2nd to 3rd at high throttle input. If you let off, then hit the throttle again, it'd shift into gear.

 

[Sherrow74]

I put new plugs and wires in with the distributor just to be safe. I'm gonna try replacing the rubber fuel lines. The weird thing is that it just started happening all of a sudden. It drove fine until one day it stumbled and then it started doing it everytime I got on the highway

 

[splake]

Dirt in fuel tank sender? Vac modulator on trans?

 

[dvdswan]

I'm not familiar with auto trans but does it have a lock-up converter? If my memory serves me correctly, at times it does not, but a lock-up converter engages when it reaches a certain speed, is it possible it is stuck on when you hit third?