I need help getting my truck dialed in

[1970heavychevy]

I have a 70' c10 but the motor is a 70' 350 out of an Impala. It has an Edelbrock #1405 carb. and Edelbrock intake. I bought it from my dad 2 years ago and he bought the motor rebuilt 3 years ago before that. So the motor was rebuilt 5 years ago. My dad ran it 2 years before it started acting up on him. The issue I'm having is.

The truck fires up with no problems and idles with no problems (it does have an aftermarket cam so we were told).
When I take off most of the time it runs great, lots of powers, gets a wheel in second (auto th350 trans). But when I get down the street a few miles everything seams to bog down and I have no power and have to limp home.
I have replaced all the fuel lines and filters. Replaced the fuel pump and installed a regulator. I have cleaned out the carb.

What next? I am frazzled!

[cdowns]

replaced the filter/fuel sock on the pickup tube in the tank? trtried taking gascap off to see if it solves problem?if HEI dizzy changed module?

off the top of my head thats the 3mosyt common problems

[1970heavychevy]

My dad had the sock changed. I am starting to move into the ignition area now. Take the gas cap off and run it? It is HEI but I have not checked the module. Don't know much abou it.

[ChevLoRay]

Modules are either good, or they aren't.....in my experience. Whenever they are installed properly, the installer should use dielectric "grease" (it's white, and specifically for this purpose) that serves to insulate the module from the transfer of heat from its mount, heat being the primary enemy of electronics.

It could be that the installer didn't use the grease, but who'd know unless you pull the module out and then you wouldn't likely see any of it, anyway.

The idea of pulling the gas cap off and running it has to do with whether or not the tank is vented and the cap isn't or vice versa. In theory, if the tank isn't vented, nor the cap, then removing fuel from the tank creates a vacuum and that will end the suction effect of the fuel pump. To me, that doesn't sound like your problem, either.

The sock in the tank having been replaced is a good thing. Have you looked at the fuel filter to see if there may be some sediment/rust trapped in it?

What about your coil? Could it be breaking down? Checked the rotor and where the coil sets in the cap to be sure there isn't any cracking in the top of the cap where the coil sits? What about the spring-loaded contactor that fits below the coil and above the rotor? What about the cap? Wires? Plugs?

The fact that it starts and runs, then deteriorates is telling me that it will run, but something goes to pot after it warms up. You gotta think about what it may be that could be breaking down as it heats up. To me, that's an electrical or ignition issue, with ignition getting the nod from me.

Whenever you find the solution, you'll say, "I shoulda checked that first", and you'll think it is simple, which hopefully it will be.

[1970heavychevy]

I thought it was HEI but its not. The cap does not have a coil on top. Should I switch it over? And can I get out with some money still in my bank? Not a lot in there to begin with.

[seldomseen65]

Originally Posted by 1970heavychevy

I thought it was HEI but its not. The cap does not have a coil on top. Should I switch it over? And can I get out with some money still in my bank? Not a lot in there to begin with.

hey let the rest of us know how your doing with the problem in losing power in your truck there are a lot of us wondering how your doing OK.:Chevy: a lot of good ideas that will help you out there. it's been since Oct. 08 when you posted.

[seldomseen65]

Originally Posted by 1970heavychevy

I have a 70' c10 but the motor is a 70' 350 out of an Impala. It has an Edelbrock #1405 carb. and Edelbrock intake. I bought it from my dad 2 years ago and he bought the motor rebuilt 3 years ago before that. So the motor was rebuilt 5 years ago. My dad ran it 2 years before it started acting up on him. The issue I'm having is.

The truck fires up with no problems and idles with no problems (it does have an aftermarket cam so we were told).
When I take off most of the time it runs great, lots of powers, gets a wheel in second (auto th350 trans). But when I get down the street a few miles everything seams to bog down and I have no power and have to limp home.
I have replaced all the fuel lines and filters. Replaced the fuel pump and installed a regulator. I have cleaned out the carb.

What next? I am frazzled!

does it have an HEI distributor in the motor???, if it does ,,check the module in it,, could be a bad module,,this happened to me years ago with a 79 fire bird.
it would act the same way you described. usually gets hot after a time ,, then you have to let it cool and it will run for a while,, if you don't have an HEI,, it would be a good idea to get one put in.

[Boog]

This one is a few months old now but the OP didn't add anymore to it. Wonder if he got it worked out?
I think it's worth mentioning a restriction in the exhaust system can also cause one to lose power like that.

[seldomseen65]

Originally Posted by Boog

This one is a few months old now but the OP didn't add anymore to it. Wonder if he got it worked out?
I think it's worth mentioning a restriction in the exhaust system can also cause one to lose power like that.

boog, I'm thinking maybe the butterfly valve on the exhaust could be stuck and your right it could be that in the exhaust system, causing it to lose power like that, thanks for that thought, i hope we have helped him find the cause to his problem.