1971 Ford Mustang Backfire

1971 FORD MUSTANG
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CAPTTHUNDARR
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Engine Performance problem
1971 Ford Mustang V8 Two Wheel Drive Automatic
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Got a 71 mustang conv. that we put a create motor from jeg's in. The motor is a '87 thru '96 5.0 HO(it came with a 351 cam).Set the #1 piston to TDC on the compression stroke. I was told by the engine manufacture (Blueprint engineering) to besure to use the 351 firing order which I did. With the engine running and warmed up, any timing above 0 deg. BTDC the engine will backfire through the carb when the throttle is cracked quickly but revs smoothly when it is opened slowly. I don't get it.
Sep 8, 2008 at 9:19 PM
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MMPRINCE4000
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I would check valve lash, wheather solid lifters or hydraulic. Sounds like a valve is hanging open.

Also call Jegs tech support, they have a pretty good tech. section, if only to let them know you are having a problem before the warranty runs out.
Sep 9, 2008 at 5:43 AM
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CAPTTHUNDARR
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What about the distributor beong "1 tooth out" ?
Sep 9, 2008 at 9:29 AM
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MMPRINCE4000
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[quote:7b7c28760e="captthundarr"]What about the distributor beong "1 tooth out" ?[/quote:7b7c28760e]

If the engine is at #1 TDC and you install the dist. with rotor pointing at #1, you should be OK.

Check with Jegs and see if the timing chain was installed advanced.

Generally when you have too much advance the car will be hard to start, crank slowly, because the ign. is firing the cylinder way too soon.

The fact that it is back firing, indicates an incorrect firing order or a valve hanging up, or a distributor problem.
Sep 10, 2008 at 6:06 AM