4th gear no engine power

225 V6 and the Rochester 2G carb. I have power down low, and it seems to accelerate well and idle well. I was plowing snow fine. Once I reach 4th gear and try to accelerate or cruise there is no power and it 'coughs' and hiccups. If I let off and am satisfied to run at 45-50 it won't cough or hiccup.

It was fine earlier this summer, and I was able to pull up to 70 or so, and now not even close.

Fuel pressure seems ok as when I pull the line off it is still under pressure.

Changed the fuel filter.

New plugs, wires not that old.

I currently have the carb torn apart to clean it, and hope to have a rebuild kit tomorrow. Is there something else I should be looking at?

Thanks,

 

Check the vacuum advance in the distributor, check dwell on the points, check the mechanical advance for operation, make sure all the passages are clean and clear in the carb during the rebuild. We used to use WD -40 with a straw nozzle to check the passages. Make sure you wear safety glasses. WD in the eye is not pleasant.


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I believe its a bad Vacuum leak.... I had same thing

accelerate, low end power fine. Hit 50 third gear go about a sec or two then nothing, starts spitting and what not. downshift and slow down everything works good, do it over again... If you do it enough I would have to let engine cool slightly. That second gear though doing about 40 worked fine...

the bolts on the carb body to lower carb plate where loose, they rattled loose. I tightened them up when I realized carb was loose, everything back to normal.

 

No points, I converted to the Pertronix, how do I check the vacuum advance?

 

Did the same once with Berryman's in a can. Never thought opening your eyes under a garden hose would be that easy... Glasses, goggles, face shield or someone less valuable is a must.


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Carb cleaner, right back into my eye... won't ever do that again.

 

X2 on carb clean. My eyes water thinking about it.

 

Easy way to check the vacuum advance-

Remove distributor cap
Remove vacuum line from vacuum advance
Install vacuum line long enough to reach to your mouth
Suck on vacuum line
You should see distributor plate move when you draw the vacuum
You should be able to hold the vacuum with your mouth without it dropping
If either don't occur, replace the vacuum actuator.
If you get a mouthful of gasoline, you chose the wrong line.

 

A faulty vac advance will not cause a lack of power under acceleration. It sounds more like fuel starvation. It may be helpful to hook up a remote fuel pressure gauge that you can watch while you're driving. If that's not an option, unhook the fuel line from the pump and blow air back through the line (take the gas cap off first). There may be a small obstruction in the line. Check the carb thoroughly while you've got it apart, could have had a piece of debris stuck in a jet. Make sure the distributor hold down didn't loosen up and the timing slipped. If, after all that, it still runs poorly, try a different fuel pump.

 

Honestly, I found the problem, I must have bumped the timing working on it. It was too advanced. I put the light on it and retarded it and that fixed it.

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