Tweaking after rebuild
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Junior User
Joined: Sep 2003
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Tweaking after rebuild
Hello,
I have an 86 f250 with 460 and holley 4180 carb. I rebuilt this summer and was reasonably satisfied. I did have two issues - 1) my idle was way too rich and 2) the truck surged at highway speeds ever so slightly.
The truck drove ok and gas mileage was fine. 10.5 mpg combined and a whopping 11.5 for a fishing trip into the mountains.
So I turned back the idle mixture screws 1/4 turn the other night. WOW! The throttle response and driveability is outstanding. My 5700# truck drives like a mid sized car. Much more enjoyable to drive. I could not believe it was the same vehicle. So hopefully I cured problem #1 and have dialed in the idle.
Problem #2 is now more pronounced as their is even less fuel at highway speeds. So here is my question: do I open up the secondary butterfly just a touch or do I get softer springs?
Thanks.
Larry
I have an 86 f250 with 460 and holley 4180 carb. I rebuilt this summer and was reasonably satisfied. I did have two issues - 1) my idle was way too rich and 2) the truck surged at highway speeds ever so slightly.
The truck drove ok and gas mileage was fine. 10.5 mpg combined and a whopping 11.5 for a fishing trip into the mountains.
So I turned back the idle mixture screws 1/4 turn the other night. WOW! The throttle response and driveability is outstanding. My 5700# truck drives like a mid sized car. Much more enjoyable to drive. I could not believe it was the same vehicle. So hopefully I cured problem #1 and have dialed in the idle.
Problem #2 is now more pronounced as their is even less fuel at highway speeds. So here is my question: do I open up the secondary butterfly just a touch or do I get softer springs?
Thanks.
Larry
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Joined: Dec 2001
Posts: 22,436
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From: Louisville,Ky.
Sounds like you need larger jets. Opening the secondaries won't help the surging while cruising. Go up about 2 sizes from what is in it now and it should be fine. It won't effect the idle mixture when installing the larger jets.
Thread Starter
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Junior User
Joined: Sep 2003
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I was wondering about that. I bought this truck in the spring. It is a california truck and has size 61 jets. Any thought about whether 61's are stock or not? Given the very limited input the PO had on maintenance, I assumed that the carb had not been touched.
Thanks.
Larry
Thanks.
Larry
