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Fresh 351W. MSD ignition. Fires on all cylinders but when I remove #3 wire, it still misses (doesn't get rougher). Compression 125. Valves adjusted. Checked for vaccuum leaks. Doesn't fire at higher R's. 72 engine firing order checked with the book. Wires not crossing. I see no breaks in valve springs.
O-K Guru's, what the hell is wrong?
Missed the car show this weekend. /forums/images/icons/frown.gif
JB's Dad, JB
 

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longshot but you may have a bad plug or the gap is too small or none at all so no spark. check the plug
 

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I once got my bronco a "new" set of spark plug wires from the dealer.....

and it misfired.....After changing the plugs, cap and rotor.....I just tried replacng the faulty cylinder with one of the old wires and it was faulty.....

So I asked Ford for a new wire and they obliged....

now it purrs like a happy kitten...

good luck!!!

sometimes things ARE this simple!!!
 
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We tried switching plugs and wires. No difference. The plug fires. Must be mechanichal. Valve problem, timing, or I don't know what. VERY stumped! We even blew air into the cylinder to check for leaks. Found none....


JB
 
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I talked to another mechanic this AM. Suggested trying a different distributor. Could be firing that cylinder at the wrong time. Is this possible? I'll try anything!

JB
 

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maybe an extreme intake leak on just that runner? (gasket?)
 

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So, after running the engine awhile with that cylinder not working, then pulling the plug out, how does it look? Completely clean and dry and like new? No oil or fuel on it? No color? I'll assume you've verified the valvetrain for #3 is functional, yes? Remember, it'll make cranking pressure even with the valves non-functioning...

Last time I saw this problem, it was a flat cam...

Tell us more about service work you've done recently and/or any other odd symptoms you've noted. Also, how new/old is this engine? OEM or modified? Details, details...*G*

Get back to us....
 
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