boggs down in gear


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Old 04-13-06, 11:16 AM
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boggs down in gear

I have a '79 Ford E250 van. 460, holly model 4180. Runs great in park but boggs down when I put it in gear. I have checked the fuel pump and it is definately getting enough gas. I've used almost 10 gallons in the last two days without even getting it out of the drive way. I don't know anything about engines but I did take off the front and real bowls on the carb and adjusted the floats. No help there. Someone told me to check for vacuum leaks. There are three hoses plugged and I have no idea where they are supposed to go. I have a chilton's manual but can't understand it.
 
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Old 04-13-06, 04:00 PM
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'Bogs down' is really a terminology for an engine that apparently has no misfire, but just has no power...as if someone has their foot on the brake. With that in mind, have you checked your brakes? Ever gone for a little ride and then got out of the van and felt the hubcaps to see if all 4 feel uniform temperature (relatively cool, to at worst, just slightly warm), without finding one or two that are like you could fry an egg on them?

If could be that your timing is severely retarding when you step on the gas pedal under load also. Timing 'advance' is really timing retard, actually. It's sort of a misnomer. Under load, like in gear and going up a hill, you naturally have to push down more on the gas pedal which reduces the manifold vacuum pressure which then retards the timing, so you do not get 'knocking'. Knocking under load conditions is due to firing of plug when the piston is too near top center and due to the load, the piston cannot be easily pushed, and so it knocks due to the explosive 'ring' sound off the top of the piston.

So, if I were you , I would check some of these things: Make sure your van can free-wheel easily...be pushed easily in neutral to rule out sticking brakes or even a wheel bearing issue. Test the compression of the cylinders, as weak cylinders will allow an engine to idle just fine and sound like it has good pedal response. But under load conditions, the motor is toast. And check the timing AND the advance curve. (If you had a fuel issue, like starvation, this problem becomes worse and worse, like under load up a hill with the pedal really depressed and literally will starve out the engine. But with those other issues, it (the bog) remains more constant without actually killing the engine.

It's possible you could have a jammed up exhaust somehow also. I would crawl underneath and make sure something didn't get caved in. If you still have your cat converter, these have been known to collapse inside and can restrtict the exhaust and create a bog also.
 
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Old 04-13-06, 04:14 PM
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power valve

Everything in the first post should be checked. Now my 79 F350 with 460 and same carb backfired a while back and I suspect the power valve is bad. One backfire can blow it out. its the round deal that is inside the front bowl. When you take the cover off it screws into the carb its about an inch round. Mine does the same thing boggs down and everything else checks out I just have not changed mine pout since it does not get used much.
 
 

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