300 runs rough
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Freshman User
Joined: Aug 2007
Posts: 33
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300 runs rough
Anybody have any ideas?
I have a 74 F-100 with the 300 I-6. the motor only has about 17000 miles on it. BUT it runs rough, it hesitates, especially when its cold.
I tried changing the timing, it was set at 6 BTDC, i tried several different timings all the way up to about 15 BTDC at that timing the truck ran GREAT, sounded very smooth, and fired right up, BUT it started pinging really bad under acceleration. I played around with it a bit and ended up at around 4 BTDC. But it is still running rough, and hesitates.
The plugs, wires, cap, rotor, and points are all new. dwell meter says it is within acceptable range.
I ran a compression test on the motor. most of the cylinders were about 120 psi, however one was about 140, and one was about 150 is this somethign i should be worried about? what is an acceptable range for this motor?
any help would be appreciated.
I have a 74 F-100 with the 300 I-6. the motor only has about 17000 miles on it. BUT it runs rough, it hesitates, especially when its cold.
I tried changing the timing, it was set at 6 BTDC, i tried several different timings all the way up to about 15 BTDC at that timing the truck ran GREAT, sounded very smooth, and fired right up, BUT it started pinging really bad under acceleration. I played around with it a bit and ended up at around 4 BTDC. But it is still running rough, and hesitates.
The plugs, wires, cap, rotor, and points are all new. dwell meter says it is within acceptable range.
I ran a compression test on the motor. most of the cylinders were about 120 psi, however one was about 140, and one was about 150 is this somethign i should be worried about? what is an acceptable range for this motor?
any help would be appreciated.
Senior User
Joined: Oct 2004
Posts: 289
Likes: 0
Sounds like you may have an EGR problem. The EGR valve may be stuck partiall open, or just too much EGR. Somewhere on this site is info on making a EGR restrictor plate if its just too much EGR flow. but look for a stuck valve or disable it temporarly if it is free and see if this makes a difference.
