/6 sputters under load

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Dodgex2

Dodgex2

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Hey guys,
Here's my set up- 75 Dart Sport /6 Holley 1 barrel. Plugs, Dizzy cap, rotor and wires fairly new, timing set at 10*

Problem- Engine runs good and smooth until I have to give it a lot of gas under load (like up hill or passing) Under load engine starts to sputter and loose power. Seems to do it more/or worse at higher speeds.

Thanks for any and all help, Matt
 
Dodgex2 said:
Hey guys,
Here's my set up- 75 Dart Sport /6 Holley 1 barrel. Plugs, Dizzy cap, rotor and wires fairly new, timing set at 10*

Problem- Engine runs good and smooth until I have to give it a lot of gas under load (like up hill or passing) Under load engine starts to sputter and loose power. Seems to do it more/or worse at higher speeds.

Thanks for any and all help, Matt
Click to expand...

sounds like its leaning out... you have good fuel pressure and filter? how is the float level?
 
Fuel filter was replaced about a month ago, not sure about pressure. Carb was rebuilt about 6 months ago and float set then. I had issues with it running rich at idle ie; black soot on the drive way. I turned the mixture screw all the way in, which was only about a 1/4 turn, it helped some.

I forgot to mention I'm at 6000ft.

Thanks for the reply, Matt
 
Dodgex2 said:
Hey guys,
Here's my set up- 75 Dart Sport /6 Holley 1 barrel. Plugs, Dizzy cap, rotor and wires fairly new, timing set at 10*

Problem- Engine runs good and smooth until I have to give it a lot of gas under load (like up hill or passing) Under load engine starts to sputter and loose power. Seems to do it more/or worse at higher speeds.

Thanks for any and all help, Matt
Click to expand...

Make sure choke is fully open.
Adjust air/fuel for highest rpm or vacuum.
Rule out any vacuum leaks.
Timming set at 10*means nothing.
What's your total timming ? Total timming should be no more than 32*
Make sure your getting a good pump shot when you hit the carb.
How's the coil ?
Double check the cap for a hairline crack or cracks.
Double check plug wires for good connections at the plug and dist cap.
Valves adjusted ?
 
Tune-up parts and technique suggestions in this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. My initial guess is that the carburetor (still) has problems. Idle mixture screw only 1/4-turn out isn't normal, even at 6k feet. Could also be a problem with your EGR system (is it intact? Removed? Partially disabled?). Is this an original high-altitude car with catalytic converter? Does it have an OSAC valve?
 
He is saying no remanufactured or rebuilt carb is good anymore. Go buy yourself a new one or rebuild your OEM one yourself with a good kit. I cant vouch for a professionally rebuilt carb, but rebuilding your own is about a 30 minute job on the bench....and mother Mopar knew best when they set these up with stock EGR, OSAC, PCV ...LOL.
 
If it's missing under load, that is probably an electrical problem with the ignition system. If it's surging and acting like it's running out of gas, it's likely a weak fuel pump or partially plugged fuel line. A fuel pump volume test would tell pretty quick if that is the problem. If the supply is plugged, don't forget to check the sender tube and filter sock. Check to see that the fuel hoses from front to rear are in good shape. A crack on the supply side of the pump will allow air to be sucked in the line instead of fuel from the tank.
 
A bad acc. pump would cause an initial hesitation when you step on the throttle but doesn't have any effect once it stops moving.
 
Thanks guys, sorry been super busy. I plan on getting back to the Dart this weekend. Great info I'll get some answers and get back. Matt
 
check Bill Dedman's post from yesterday, " has anybody ever seen this". Check your rubber fuel line for inside wear, gets soft and inside diameter is too small. Not enough fuel under load.
 
Thanks Kazoom, I replaced the airfilter and coil. The problem is more of a miss/sputter under load. The coil seemed to help a bit I feel more power (surges almost) but still getting the sputter. I'm going to replace that fuel line next.

I have to borrow a timing light to check total timing.
The choke fully opens
Getting good shot in the carb
Cap and wires all check out
Have found no vacuum leaks
EGR system is intact

I need to do a search to see how to adjust the valves, how do I know if it needs it?

Thanks again, all you guys are a huge help!
 
If you've never adjusted the valves, it needs it! You'll find many threads on how to do it on here.
 
cudamark said:
If you've never adjusted the valves, it needs it! You'll find many threads on how to do it on here.
Click to expand...

I found a great thread on it from /6 dan. Looks like I know what I will be doing this weekend. Thanks
 
Replaced that fuel line.....it was fine.

Next I need to try my hand at adjusting the valves
 
Dan did mention the catalytic converter. Your car have one?
 
It does, anyway to tell if it's bad?

I figured the valves needed adjusted anyway and a gasket is not too expensive.......
 
Not pretty but loosen the 2 flange bolts where the pipe meets the manifold to allow the exhaust to exit before the cat.If it runs better,good chance the cat is clogged.
 
The neighbors will love that lol

I just worry I'll break the bolts, heat will be a must. Thanks
 
The good thing is they are not studs and simple to swap if they break.
 
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