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Hesitation on 79 trans am

I'm sure my 79 TA is hesitating under heavy acceleration (foot to the floor) but i'm not sure where to start looking for the problem. It's just had a new radiator, new plugs, air filter, oil & filter & a full tune up, but i'm sure its hesitating. It's as if its changing up and down gears, am i just imagining it? anyone know what it could be? I've only had the car a couple of weeks so i'm still learning about its ways. Normal cruising speed is fine, its just when it gets above 60mph

Thanks

Reply to
GH
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A little more info would help.

What engine/tranny do you have?

Does it only hesitate under full throttle above 60mph? That's what it seems from your post.

Does it hesitate if you're stopped and you floor it?

Does the hesitation seem like it's bogging down and then it kicks in , or is it more like the engine is missing(running rough) ??

Is it only when the 4bbl opens?

Did it happen before the tune up?

Jay S

Reply to
Jay S

You may be describing the famous Quadrajet "bog". If you are flooring it, then the secondaries should be opening, assuming you have a 4bbl carb. If the engine bogs when the secondaries open it's usually because the spring tension on the secondary choke plates it too loose, and the engine gulps at the sudden influx of extra air. The screw for adjusting that is rather hard to see without taking off the carb and holding it upside down. It may be an Allen head screw GW

GH wrote:

Reply to
Geoff Welsh

Yup..sounds like the q-jet bogging. Also check that the fuel pump is flowing enough GPH and has enough pressure.

Jay s

Reply to
Jay S

I'll assume it's a 403 olds powered automatic with an original carburetor.

The quadrajet secondaries are vacuum operated, and they're notorious for "bogging" when opening too soon. This is adjustable. It may also not be getting enough fuel, or have one of the jets stopped up, or something like that. The carb may be in good shape, or it may not; not enough info to tell.

Reply to
Joe

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