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I am still fighting with the motor since i put the heads back on, the firing order for a 351 all my motor does is back fire. if i sdet it to a 302 then the motor runs. the only problem then is that at light pedal accel she pops and pops, but hard accel she dosent pop. also dosent have the power she did before i took the heads off. I did the whole finger over the whole compression stroke thing, but things arent making sense. How can i tell if my motor is a 351 or a 302 it was sold to me as a 351 now i question that. The heads and intake are definatly 351 that i know. I have a oval air cleaner that says cougar on it and it just fits under the hood so the motor is pretty high. are their differences in the oil pan or the dipstic, the oil dip stick is coming up on the front of the motor. Anyway any help is appreciated.

what would you guys do if this were your motor?
 

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F.O.???

THE 351 AND 302 ARE PRITTY MUCH THE SAME THE BIG DIFFERENCE IS THE BORE AND STROKE, THE 351 WILL HAVE A WIDER INTAKE MANIFORLD THAN THE 302, LOOK AT THE CASTINGS ON THE INTAKE, JUST FOWARD OF THE CARB. SHOULD BE THE FIRING ORDER, THE 302 F.O. IS 15426378. WATCH OUT THO THE CAM IS ALSO INTERCHANGABLE. IF YOU HAVE A 351 AND A 302 CAM YOU NEED TO USE THE F.O. FOR A 302. LOL
 

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ok, if you are sure its a 351 intake, then it is a 351. the intakes wont fit onm a 302. and the fact that its tall enough to almost hit the hood sounds like a 351 too. as far as everything else, are you sure that the firing order is right?? what about the timing? sounds like one of those is off. go and check them and see how it goes. let us know. and yes the dipstick comes out in front iof the engine. passengers side near the upper radiator hose.
 
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