heres the problem in my car 350 with a 350 th, rebuilt about 15yrs ago, fuilee heads, Z28 intake mainifold,quadrejet carb 4b,
the problem happens about 65mph+ my car starts to surge and shake and it only gets worse the faster i go, i cant even go over 120mph it gets so bad if any body has any idea what is causeing this so i can fix it would be very helpfull thanks.


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you could possibly not be pushing fuel fast enough, im assuming you are testing this by slowly increasing speed. are you positive that it is speed dependant and not RPM dependant?

 

ya because i can hold it in 2nd and it dosent do it intell i shift in to third about 70mph but i could be wrong, what do you mean not pushing enough gas, carb our fullpump


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i would say pump, from what u said its not speed dependant but rpm dependant. you may not notice it much in low gears because you dont spend much time in higher rpm, but this is dangerous if it really is fuel pump because it means your going lean.

Im actually not a carb man personally, so I do not know what your fuel pressure should be, but you can get a gauge that will tell you if you are low. low pressure is enough for lower rpm, but when ur motor is pumping faster, it needs that fuel to be there.

you could also try cleaning out the carb with.... well, carb cleaner . regardless the problem seems to be that the motor isnt getting what it needs when its trying to breath really fast.

 

ok thanks i will check it out.


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i tried the pressure check but while it was turning over the needle was jumping all over, i have never done this before and im not sure if i did it right if any body has any pointers let me know


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