1972 F100 having hesitation during acceleration
#1
04-07-2018, 02:16 PM
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1972 F100 having hesitation during acceleration
I have a 1972 F100 with a 390. Inhave only owned it for bout 3 months. Was running pretty well. But I decided to do a tune up since it had been sitting for 4 years prior to me purchasing. I replaced plugs. Set gap to .034. I replace points and set gap to .017. Dwell meter reading 30. Originally had set to .021 but changed to get dwell angle. I set timing to 6 BTDC. It now has a hesitation that it didn’t have before. It hesitates and jerky slightly now at all speeds. Rechecked everything I did. Not a very experienced mechanic looking for suggestions.
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04-07-2018, 04:06 PM
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readjusted time timing to just above 10. Idles better. But still has a hesitation / jerkiness when accelerating. May be better than before but not sure. I rechecked everything I did and everything appears right.
#6
04-07-2018, 04:18 PM
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I did not replace the condenser. Thinking I should just get a new set of point and a new condenser. But since I didn’t change it the first time doesn’t sound like that could be the case. Thoughts?
#7
04-07-2018, 04:39 PM
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#8
04-07-2018, 05:19 PM
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wires not switched. Was careful when I removed and replaced. Also found firing sequence online and checked to make sure. Rechecked to ensure wires were on tight. I guess I could put old wires back on to check and old cap and rotor.
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04-07-2018, 06:46 PM
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Ok. I out the old wires, cap,and rotor back on. No luck. Still not running right when I accelerate. Rechecked with dwell meter. At 29. I rechecked the pints gap as well. Rechecked timing. Just above 10 BTDC. It may be time to let a real mechanic look at it. FYI. For good measure I replaced the fuel filter as well for no good reason.
#11
04-09-2018, 05:09 AM
#12
04-09-2018, 11:00 AM
Are you checking the timing with the vacuum hose on or off at the distributor? I would pull it while doing timing. Most are connected to a ported vacuum source but someone may have moved it to manifold vacuum which would change your base timing quite a bit. Also have you checked timing advance both centrifugal and vacuum? Could have issues with either. Rule of thumb for most engines is total advance base+centrifugal+vacuum should hit around 40 degrees on a stock motor.
Have you looked into the carb with engine off to see if you get a squirt of fuel when you work the throttle linkage? Could be a carb issue that has just showed up at this point in time.
Have you looked into the carb with engine off to see if you get a squirt of fuel when you work the throttle linkage? Could be a carb issue that has just showed up at this point in time.
#13
04-10-2018, 04:16 PM
Hotshot
Put the Dwell meter and timing light back on it. Start up the engine and watch the meter as you rev it up to about 2000 RPM with the vacuum hose on the vacuum advance can. The dwell should not change any more than 2-3 degrees. If it does your points breaker plate is bad.
Also rev it back up to about 2000 RPM and hold it there. Watch the timing mark. It is supposed to advance then stabilize when you get to the RPM you want and hold it there. If the timing mark bounces around it is either a worn timing chain or a bad condenser.
Also rev it back up to about 2000 RPM and hold it there. Watch the timing mark. It is supposed to advance then stabilize when you get to the RPM you want and hold it there. If the timing mark bounces around it is either a worn timing chain or a bad condenser.
#14
04-11-2018, 01:15 AM
Bogging down, stumbling, hesitating from a dead stop or when accelerating at speed are indicative of defective 2100 series 2V carb accelerator pump and check valve.
Parts available by themselves, also come in the carb kit.
D4AZ-9A586-A (replaced C2AZ-9A586-B) .. 2100 series Auto-Lite/Motorcraft 2V Carburetor Kit (Motorcraft CT-499-D) / Available from Ford & auto parts stores.
Same: 1962/74 Passenger Cars & F100/350, 1966/74 Bronco & 1969/74 Econoline.
Parts available by themselves, also come in the carb kit.
D4AZ-9A586-A (replaced C2AZ-9A586-B) .. 2100 series Auto-Lite/Motorcraft 2V Carburetor Kit (Motorcraft CT-499-D) / Available from Ford & auto parts stores.
Same: 1962/74 Passenger Cars & F100/350, 1966/74 Bronco & 1969/74 Econoline.