Timing
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Laughing Gas
Joined: Mar 2016
Posts: 757
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From: Cheyenne, Wy
Timing
Hello. I'm sure this has been covered 87 times. Looking for correct links to threads or an answer. Please.
79 f100 302, automatic, 2wd. Truck came from 7000/ft elevation (high desert) and now is below 650/ft elevation (Michigan). What do I do to the timing to get it to start correctly? It will start with ether and fine all day. Is it running lean or rich? Turn it clockwise or counterclockwise? Looking for temp fix because in about a week going back to high elevation. It just does not like .this low elevation.
79 f100 302, automatic, 2wd. Truck came from 7000/ft elevation (high desert) and now is below 650/ft elevation (Michigan). What do I do to the timing to get it to start correctly? It will start with ether and fine all day. Is it running lean or rich? Turn it clockwise or counterclockwise? Looking for temp fix because in about a week going back to high elevation. It just does not like .this low elevation.
Tuned
Joined: Apr 2023
Posts: 363
Likes: 108
if it was running correctly at 7k feet it would be lean at 650. there is less oxygen to a given volume of air at 7k feet than at 650 feet.
counter clockwise would make the idle richer, but i think this would require a jetting change. i am NOT an expert on this type of thing though
counter clockwise would make the idle richer, but i think this would require a jetting change. i am NOT an expert on this type of thing though
Lead Driver
Joined: Jul 2017
Posts: 9,603
Likes: 1,174
From: San Jose, CA
And when it’s cold, make sure the choke is closing sufficiently. Too far and even a lean running engine will have a hard time starting.
But not far enough and I’m sure it would be very hard to start when cold. Hence the starting fluid/ether.
But yes, it’s a main jet issue and nothing to do with the idle screws.
The idle screws will need to be readjusted for new jetting, of course, but I doubt that they are much of a factor, if any at all, in the hard starting issue.
But not far enough and I’m sure it would be very hard to start when cold. Hence the starting fluid/ether.
But yes, it’s a main jet issue and nothing to do with the idle screws.
The idle screws will need to be readjusted for new jetting, of course, but I doubt that they are much of a factor, if any at all, in the hard starting issue.
Laughing Gas
Joined: Dec 2020
Posts: 869
Likes: 186
From: Near my truck
The timing will be about 7 degrees too advanced for 650 feet.
Standing in front of the truck, facing the truck, one would turn the dizzy counter clockwise to retard the timing.
The main jets would be maybe 6 sizes too small, and thus way too lean.
The optimal temp fix would be a main jet change.
I don't think retarding the timing would make a significant difference, so I'd focus on the main jets.
That said, if you're only cruising around at low rpms, which would be the idle/mains circuit, you ''might'' get away with turning your mixture screws at least one turn out.
Standing in front of the truck, facing the truck, one would turn the dizzy counter clockwise to retard the timing.
The main jets would be maybe 6 sizes too small, and thus way too lean.
The optimal temp fix would be a main jet change.
I don't think retarding the timing would make a significant difference, so I'd focus on the main jets.
That said, if you're only cruising around at low rpms, which would be the idle/mains circuit, you ''might'' get away with turning your mixture screws at least one turn out.
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