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I just swapped a 390 into my 74 gran torino, I got it running and driving but the engine wasn't running the best. I parked the car this morning to try and mess around with the engine timing. I didn't do anything major to it before it kept backfiring through the carb when cranking and wouldn't start. I tried retarding the timing and it helped but it got too retarded to even start. It seems to be backfiring through only the secondaries and there's soot around the barrels. The car was driving just a day before, It was just having symptoms of being too lean. Thoughts?
 

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I just swapped a 390 into my 74 gran torino, I got it running and driving but the engine wasn't running the best. I parked the car this morning to try and mess around with the engine timing. I didn't do anything major to it before it kept backfiring through the carb when cranking and wouldn't start. I tried retarding the timing and it helped but it got too retarded to even start. It seems to be backfiring through only the secondaries and there's soot around the barrels. The car was driving just a day before, It was just having symptoms of being too lean. Thoughts?
A little history of the engine as how many miles since last overhaul or timing set replacement, age of fuel pump, filters, what is the carb, stuff like that?

Bogie
 

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Are the secondaries closing all the way? I have had a few that were sticky from sitting around, mashed the throttle without the engine running to check for full throttle. Restarted crappy with a high idle, secondaries hadn't closed all the way, creating a huge vacuum leak.

Dave

Sent from my moto x4 using Tapatalk
 

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Are the secondaries closing all the way? I have had a few that were sticky from sitting around, mashed the throttle without the engine running to check for full throttle. Restarted crappy with a high idle, secondaries hadn't closed all the way, creating a huge vacuum leak.

Dave

Sent from my moto x4 using Tapatalk
To clarify this point:

In my experience, the secondaries should not be set so that they are closed all the way when they are closed. They should be cracked slightly. If they are closed tight, this could be causing you some headache.

I would advise putting some blue loctite on the set screw for the secondaries to assure that they stay where you put them. If the set screw backs out even 1/4 turn as the engine runs, you will find yourself chasing it down again :thumbup:.

Like Dave said though, they should close "all the way" as in "as far as they are allowed to before hitting the idle set screw."
 
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