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Discussion Starter · #1 ·
The more my engine warms up the worse the car runs. I have been having this problem for a long time and still can't remidy it. When the car is up to operateting temp, and I am just cruising along the car works fine. But if I push it, like driving through hills or driving down the freeway, the car starts to miss at full throttle and gets worse the longer I drive. It gets to the point that simply touching the gas causes it to miss and stumble. Sounds like a lean pop, condition. I have to pull over and let it cool down, although the motor does not seem overly warm (Yes I need to buy a temp gauge), I can hold on to the upper rad hose, and it isn't overflowing.

I have a feeling it is a fuel problem. I switched the pump without any luck. Could the carb be heating up and boiling the fuel? Also at wide open it always has a lean pop. The Quadrajet carb was rebuilt a 1000 miles ago, but has never worked properly.

Doesn't really matter, new motor, carb and fuel system goes in by the end of the month.

Thanks
Steve
 

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Sounds like the car's going into a 'vapor lock' situation, but I'm not the worlds best mechanic. Is the fuel line anywhere close to the headers/exhaust manifolds? You really need to find out what temp the car is running at, but you're right, it does sound like the fuel is percolating before it reachs the plenum to me.

I'm sure someone here will give you far better advice than this...I'm just tossing out some thoughts here.

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Sean Thomas
TC #907 ACES #4468
1970 SS 396
Photo Moderator-AmericanIron.net
 

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Discussion Starter · #4 ·
You guys are fast.

Just running a stock HEI that it getting a full 12V. The fuel line and pump are all stock. This is a stock 305 out of a 80-84 truck, according to the numbers. This is also why a new motor goes in at the end of the month.

Steve
 

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Discussion Starter · #6 ·
I know it doesn't really matter. I just like to know everything and it will really bother me if I can't pinpoint the problem.

Steve
 

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What type of exhuast are you running? Do you have a crossover or are you running duals? If it's a stock 305 out of an 80's vehicle, does it have an EGR valve and is it functioning properly? How about the heat riser valve, if you have one? Is IT opening all the way when the engine heats up? Do you have the intake manifold crossover blocked off (under the carb)? As you can see, there are PLENTY of avenues you can take to diagnose this condition. As for a temperature
guage, don't get me started!
If the idiot light isn't on, and the car hasn't boiled over, chances are your coolant temperature is OK. Check all of the above. Did you have this problem before the carb rebuild, or did it start after the rebuild? Lots of possibilities. I know I've asked more questions than I've answered, but that's what troubleshooting's all about. Good luck!
s

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MalibuJerry350
TC Member #1279
Original owner '70 Chevelle.
553,000+ miles on car.
Hey, if it's got wheels, DRIVE IT!
My Chevelle: http://hometown.aol.com/erie614/myhomepage/index.html
 

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Discussion Starter · #9 ·
The problem started about two months ago, right after a 100mph blast down the freeway. I have not checked all the EGR crap and heat riser, but I will.

The new motor will not use any pieces off the old one. Maybe a few brackets, and pulleys.

Thanks
Steve
 
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