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Old October 17th, 2012, 10:11 PM   #1
twelve
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Default 78 Bronco backfires thru the carb

Well, I bought a 78 bronco. The engine is either a 351 of 400. Depends on wheather I listen to the po or the vin tag. Anyhow the engine has a 2 barrel carb, a full MSD ignition(distributor, coil, wires, box). About a week ago it started to backfire thru the carb. It usually happens after I shift gears at lower rpm's. I don't know much about carbs or tuning engines with them. Any advice y'all can give me will be greatly appreciated thanx guys.
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Old October 17th, 2012, 10:16 PM   #2
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Timing is off. See of there is any timing marks on the balancer. Is there a timing tab on the front of the block?

Do you know how to time a motor first of all correctly?
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Old October 17th, 2012, 10:30 PM   #3
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No, but my father in law is comming over tommorow and he does and I will after that.
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Old October 17th, 2012, 10:35 PM   #4
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I can do a lot of things that I've learned thru buying cars, fixing what's wrong, and learning. That's why I bought this truck. Its older than me and I have no previous experience with carb'ed engines. Gotta learn somtime.
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Old October 17th, 2012, 10:42 PM   #5
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Ill check for timing marks in the a.m. I haven't looked yet. I was suspecious about the timing, but I was gonna just turn the distributor and see if it ran better. Anyhow its prolly about time I learned how to time an engine properly.
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Old October 19th, 2012, 08:05 AM   #6
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Well, I kept at it till I got some results. I forgot to mention the brake pedal was really hard and the damn thing took forever to stop. My father in law suggested we plug the booster vacuum line and presto it smootheed rite out. Now if I have to lug it with them loud ass flowmasters past cops and not worry about it backfireing. Turn out there's a small rust hole in the booster causing a massive vacuum leak. I'm still gonna time it properly though. That and get a lesson in carb tuning.
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Old October 20th, 2012, 12:44 PM   #7
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trust me, with this engine you will get just that. :-)
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