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Discussion Starter · #1 ·
Hi,

I live in the UK and have a ski boat with a Ford V8 302 mustang engine in it. It runs a holley 6150 carb and mallory distributor.
The problem I am fgetting is that it back fires through the carb real bad under load. At tick over and reving it in neutral it runs dead smooth but as soon as it hits about 1500 rpm under load it pops and bangs through the carb.
The timing is set correctly and I have even tried retarding it to see if this helps but it does not.
I have replaced the plugs, leads, points and condensor.
I think the problem to be electrical although the american car specialist where I am thinks its mechanial ie sticky valve or worn cam.
Trying to narrow the problem down I'm not sure if its the ballest resistor. The coil I am using has an internal resistance of 3 ohms, from what I have read on the net coils with 3 ohms or more have internal ballast and do not require an external resistor, could this be the problem? Not enough voltage to the coil causing a weak spark?

Any help would be gladly appreciated as in the UK there are very few people with knowledge on these engines.
 

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To me it sounds like it's either an ignition problem or jetted really lean. Did the plugs have any carbon buildup on them when you replaced them? It might be worthwhile to try a different power valve or different main jets or something. I haven't done much tuning on Holley carbs in particular so I don't know exact jet #s, but I have seen problems like you describe when things are jetted way too lean.
 

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Discussion Starter · #4 ·
I'm going to get a full carb rebuildf kit and powervalve and jets tis weekend. Anyone recommend a powervalve and jet sizes for a stock 5.0 302 with a 650cfm holley carb?
 
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