Idle to high

Engine, ignition, fuel, cooling, exhaust

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78whiteorbs
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Idle to high

Post by 78whiteorbs »

72 f100 with 302 and stock autolite. Runs great idkes great but seems a tad high. Back the idle adjustment screw all the way and still idling a bit high. If I manually pulthumb pressure on the throttle arm in opposite direction it will idle down. Cant see anything binding ir causing restrictiin. ..maybe a weak spring???runs great just idles a tad higher than I think it should.
78whiteorbs
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Re: Idle to high

Post by 78whiteorbs »

:fr: sorry that was a 74 f100 with 302 and stock autolite
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Re: Idle to high

Post by 78whiteorbs »

Also there are two nipples one the carb when looking head on. One is ride beside the fuel inlet just to the right and one is on the passengerside. I have a vacum line ran to dustributor on this one. But not 100% certain that is correct.
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colnago
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Re: Idle to high

Post by colnago »

I would suggest checking (and/or replacing) the return spring, cleaning/oiling all joints, and possibly shortening some of the connecting linkage rods. I have an Edelbrock carb, so I bypassed the stock trapezoid, and used all-thread and Heim joints, and a stronger return spring. I think Rube Goldberg helped invent that monstrosity! You may not have anything catching, but after 50 years, you've probably collected a fair amount of crud.

Joseph

On edit, the nipples are probably vacuum ports. One is manifold, and one is ported/timed. The manifold will have vacuum when idling, and the ported should not. If you can get the engine to idle, you can put your finger to each to see which is which. For now, hook up your dizzy to ported, and cap off the manifold.
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Ranchero50
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Re: Idle to high

Post by Ranchero50 »

Define high, too high etc. A couple pics will help measurably as well.

Is the throttle lever sitting on the choke step when you are adjusting it? Fully warm, choke all the way off?

Shake the throttle shaft with the engine shut off. If it's loose you'll have issues.

Vacuum leak will give similar results.

Where are the mixture screws adjusted to? Too rich and they are covering a vacuum leak 'somewhere' Might need to pinch off the vacuum feeds and see if the RPM's drop (indicating a leak on that path).

Timing too high will contribute to high idle but should be able to control it with the screw.

Just a couple easy steps to check.
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