HELP! '77 302 troubleshooting

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Jan 26, 2016 | 10:48 AM

goopysteve

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HELP! '77 302 troubleshooting

Pulled the dist. and replaced the stator pickup coil because engine had been stalling during warm up. Reinstalled dist. and timed it at idle with vacuum advance pulled and plugged. NOW- Engine starts and idles, but sputters and backfires when the slightest throttle is applied. If I disconnect the dist. vacuum module line, engine revs fine with throttle applied. What the hell did I do wrong??

Stock '77 F100 302

Jan 26, 2016 | 11:50 AM

Tedster9

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Are you certain the distributor and rotor was reinstalled in the same position? Sounds a little bit like it's "off a tooth".

Jan 26, 2016 | 12:03 PM

goopysteve

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That is very possible, but I got it to time with the timing light, although, I noticed the vacuum module is in a different position now.

Jan 26, 2016 | 01:15 PM

Tedster9

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Possible there's a vacuum leak? Make sure the vac advance is working as it should.

Jan 26, 2016 | 06:06 PM

goopysteve

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No vacuum leaks and vac advance module is new. Engine runs smooth under throttle (off idle) when vacuum line is disconnected from distributor vac module. Engine won't run (backfires) when vacuum is applied to the distributor with throttle.

Jan 27, 2016 | 04:33 PM

goopysteve

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OK got it to smooth out by backing out the vacuum module adjustment about 6 turns. Apparently it was pulling too much timing advance when vacuum was applied.