Running too lean?

johno
Junior Member

Posts: 6

Running too lean? Nov 12, 2021 5:52:17 GMT -5 via mobile

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Post by johno on Nov 12, 2021 5:52:17 GMT -5

My F134 in my 57 FC-150 has been nothing but a struggle to get running and then running smooth. Going through numerous processes I have it running ok but it idles terrible. To get it to idle ok I need to close the choke and advance the timing. With that, it idles ok, revs ok, and able to ears drive it fairly well.
I’ve checked for vacuum leaks and I have only one vacuum line which I have a vacuum gauge on.
So I’m thinking that it might be running too lean. So since there is no perceived leak, would I be correct in looking at the idle circuit specifically the jet in that and fuel pressure.
What else would require the engine to idle better with the choke closed? With the choke open it surges and exhaust smells horrible.

Scoutpilot Administrator Posts: 2,727	Running too lean? Nov 12, 2021 7:30:46 GMT -5 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Scoutpilot on Nov 12, 2021 7:30:46 GMT -5 What carburetor is installed?
	Old fashioned service never goes out of style. “The bitterness of poor quality remains long after the sweetness of low price is forgotten.” ― Benjamin Franklin

johno Junior Member Posts: 6	Running too lean? Nov 12, 2021 14:04:32 GMT -5 via mobile Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by johno on Nov 12, 2021 14:04:32 GMT -5 938S

Scoutpilot Administrator Posts: 2,727	Running too lean? Nov 12, 2021 14:08:28 GMT -5 via mobile Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Scoutpilot on Nov 12, 2021 14:08:28 GMT -5 Pull the low speed jet and check it for a blockage.
	Old fashioned service never goes out of style. “The bitterness of poor quality remains long after the sweetness of low price is forgotten.” ― Benjamin Franklin

johno
Junior Member

Posts: 6

Running too lean? Nov 13, 2021 17:27:30 GMT -5

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Post by johno on Nov 13, 2021 17:27:30 GMT -5

I pulled out the low speed jet and it was clean. I then took out the low speed jets from 2 other YF parts carbs and compared. I don't have any correct gauge, but taking my torch file kit, I was only able to get the smallest file in my jet. The other 2 jets on the other hand, I was able to go up to the 5th file. Checking that with a micrometer it was around .027 I think. So I installed spare jet#1, reset the mixture screw to 1-1/2 turns out. Started it and bumped the timing to 5BTC. It ran. It ran good. I got it to idle pretty good with no choke. But throttle response isn't great. no midrange power. I know I need to go through the checklist of everything now that I've made progress on this but since that jet was so small, is it possible that other pieces are not sized correctly?

Scoutpilot Administrator Posts: 2,727	Running too lean? Nov 13, 2021 19:24:14 GMT -5 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Scoutpilot on Nov 13, 2021 19:24:14 GMT -5 What is possible is that you'll need to raise the Metering Rod slightly.
	Old fashioned service never goes out of style. “The bitterness of poor quality remains long after the sweetness of low price is forgotten.” ― Benjamin Franklin

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Post by johno on Nov 12, 2021 5:52:17 GMT -5

Post by Scoutpilot on Nov 12, 2021 7:30:46 GMT -5

Post by johno on Nov 12, 2021 14:04:32 GMT -5

Post by Scoutpilot on Nov 12, 2021 14:08:28 GMT -5

Post by johno on Nov 13, 2021 17:27:30 GMT -5

Post by Scoutpilot on Nov 13, 2021 19:24:14 GMT -5

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