cant get the timing right...
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Posting Guru
Joined: Jun 2004
Posts: 1,133
Likes: 3
From: Dracut, Massachusetts
cant get the timing right...
hi all,
i cant seem to get my motor running properly. its a 351m in my 77 f250. it drives and all, but its definatley not running properly, and the power is suffering. i tried to adjust the timing, but i can read the scale on the harmonic balancer. its a little rusty and i cant clean it off. so i am just kind of turning the distibutor araound. is the motor supposed to be running fast or slow? if i turn the distributor in one direction, the motor starts racing, if i turn it the other way it slows down untill it barely runs. i dont know where it should be set. the one thing i did notice, after i adjusted it, it seemed to help greatly with the problem of backfiring through the carb, it hardly ever does it, but if i listen to the tailpipe, or the hum of the motor it seems to be pulsing, and i know thats not right. any help would be great!
P.s. my dad allready told me, to take it to the mechanic, but i dont have 100+ bucks to blow on something that i CAN do myself. thanks for any help in advance!
i cant seem to get my motor running properly. its a 351m in my 77 f250. it drives and all, but its definatley not running properly, and the power is suffering. i tried to adjust the timing, but i can read the scale on the harmonic balancer. its a little rusty and i cant clean it off. so i am just kind of turning the distibutor araound. is the motor supposed to be running fast or slow? if i turn the distributor in one direction, the motor starts racing, if i turn it the other way it slows down untill it barely runs. i dont know where it should be set. the one thing i did notice, after i adjusted it, it seemed to help greatly with the problem of backfiring through the carb, it hardly ever does it, but if i listen to the tailpipe, or the hum of the motor it seems to be pulsing, and i know thats not right. any help would be great!
P.s. my dad allready told me, to take it to the mechanic, but i dont have 100+ bucks to blow on something that i CAN do myself. thanks for any help in advance!
Lead Driver
Joined: Nov 2000
Posts: 6,624
Likes: 342
From: Albuquerque
You need to find the timing marks. Use a little steel wool to clean it off and then rub the marks with a crayon and rub off the excess. Do you hear a spitting sound out of the exhaust or one side of it? That would indicate a burned valve usually. Is the popping out of the carb "regular" or sporatic?
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
A vacuum gage can be used as a quick check of valve condition. There is a link on my Club FTE web page in the links section for how to read a vacuum gage. A vacuum gage can also be used to tune the carb idle circuits. For more info on carb tuning see the carb forum.
Thread Starter
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Posting Guru
Joined: Jun 2004
Posts: 1,133
Likes: 3
From: Dracut, Massachusetts
the popping out of the carb is ONLY when the thermostat has not opened, as soon as it opens, i never have a single pop. and it used to be so bad that i could not drive it without it popping. now it hardly ever does it. i do not hear a "spitting" sound, the sound is more of a surge folowed by a very short pause. over and over. if i lightly open the throttle, it goes away, and the motor runs smoothly, wich tells me, that the idle may be too low. but i dont have a tachometer in the truck so i dont know the engine rpm. what is the timing supposed to be set at? in my haynes manual it says to go by whats on the valve cover, but what they fail to realize, after 27 years, that tag seems to disapear! and not only that but the tag is set for a motor with smog, and mine has none. i will try to get out there and clean off the scale when it finally stops raining!
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