84 302 Fuel Issue?
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Cross-Country
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From: South Jersey
84 302 Fuel Issue?
Hey all, I have an 84 F150 with a 302/C6 combo. The truck has always had its problems and i fix them as they come and so on and so forth but recently it has developed a new problem that I'm having a hard time figuring out. The 302 is rebuilt and is basically stock minus headers, an intake, and 600 cfm carb. It will start fine, idle fine, drive fine, however if i give it about 1/3 - 1/2 throttle, it starts cutting out and then will stall, mind you this is when it is in gear, If i ease into the gas it wont do it, but if its a quick throttle crack it does it. Now it has always felt a little flat but that was because the timing was off, I have the Timing set at about 10 degrees BTDC because that's where it was running/driving the best. I thought maybe it was a clogged fuel filter but that's not it, Fuel levels are good (about 1/2 way up the sight glass), all the plugs and wires are fine......Could there be crap in the carb or something? Oh the carb is a summit 600 and has maybe 500 miles on it. Thanks guys!
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Cross-Country
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From: South Jersey
Yes, but only when it is in gear, in park or neutral i can sit there and rev and hold it all day, but when it is in gear it gets about 1700 rpm and it just starts cutting out.
Fleet Mechanic
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The real test is to drive it.
Look down the carburetor and check to see if you're getting shots of fuel from the accelerator pump. If so, then the pump is working.
Then, iron out the little issues before tearing into the carb.
Have you set your float levels? Set your idle mixture, idle speeds, checked for vacuum leaks, and made sure the carburetor was tightened down?
If all is good, then you might want to consider changing the power valve.
A good general area to start is to hook up a vacuum gauge to manifold vacuum to see what the motor pulls at idle, then choose a P/V that's 1/3 the value of the manifold vacuum. If the vacuum gauge shows 18'' at idle, pull it apart and stick in a 6'' power valve. Then, take it for a test drive and see how she does.
The way it sits right now, you're either letting in too little fuel or too much fuel. You can accelerate slowly and the motor runs fine because you're keeping the vacuum signal higher than WOT acceleration. When you jam your foot to the floor at WOT and the vacuum drops down and that power valve kicks in is when you're having your problem.
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From: Virginia
Can you check the fuel bowl level on this carb? I am familiar with the old holleys with the site plugs on the side of the bowl, but I haven't messed with any of these newer carbs. If it does, I would check the fuel level, it should be at the bottom of the hole.
It does sound like a fuel starvation problem.
It does sound like a fuel starvation problem.
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Cross-Country
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From: South Jersey
I can see the float levels and they are right where they are supposed to be according to Summit.
When its under a load and i give it gas it starts cutting out and blowing out alot of black smoke from the exhaust which would mean a rich condition no?
When its under a load and i give it gas it starts cutting out and blowing out alot of black smoke from the exhaust which would mean a rich condition no?
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From: Virginia
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From: Virginia
That's a good ordinary carb, shouldn't give you any problems. Was it running good for awhile and then this problem started? Or did you just get finished installing this carb, or doing something else and it started this.
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Cross-Country
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From: South Jersey
It was always running a little flat, but thats because the timing was off, after I set the timing, the starter solenoid went, I replaced that and now it is doing this.
I thought about lowering the bowl level just to see if that would help any. I'm also wondering if maybe the timing is supposed to be where it was as opposed where it is now? Would the timing cause a super rich condition?
I thought about lowering the bowl level just to see if that would help any. I'm also wondering if maybe the timing is supposed to be where it was as opposed where it is now? Would the timing cause a super rich condition?
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From: Virginia
The timing will somewhat affect how the engine accepts the fuel. With the old holleys you always adjust the fuel level below the hole. I found it works best if you get it to where you can take the plug out with the engine running, and jounce the car by pushing down on the fender, and the fuel just sloshes out of the hole a little bit.
You said you might have clear site plugs? It may be different, so I would go with what summit said, though it won't hurt anything to experiment a little bit. A higher fuel level in the bowl will make the main venturi come in a little earlier.
You said you might have clear site plugs? It may be different, so I would go with what summit said, though it won't hurt anything to experiment a little bit. A higher fuel level in the bowl will make the main venturi come in a little earlier.
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Cross-Country
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From: South Jersey
Thanks Franklin! I appreciate everyone's input, I tried playing with the timing a little more and i fiddled with the carb a tad, wrote down everything i did, but to no avail. A few friends seem to think it maybe the cam that it is not opening up the valves far enough, but I don't know. I'm going to pull the number 1 plug and see if the TDC on the balancer is actually TDC with the motor, I should have down that from the start. I'll keep you all posted as to what is going on. Again, thank you all for your input 
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