Holley 4160 On a 460 Engine - Need Help
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Tuned
Joined: Jun 2006
Posts: 363
Likes: 3
From: Graham WA
Holley 4160 On a 460 Engine - Need Help
I'm sure there are some members here that have tuned a few Holley carburetors.
I could use some help with mine!
I have a Holley 4160 (vacuum secondaries with non-external adjustable floats). My rig is a 86 F250 4x4 manual transmission with the 460 engine.
I had my truck running real nice I thought. I went in for an emissions test and failed big time. I was way over the limit on HC and CO during the idle test. I passed cruise testing just fine. I talked to a local mechanic and after looking at my results he thought there had to be something wrong with my carburetor to have such high emissions at idle. Something like a sunk float or other defect that would dump in an overly rich fuel/air mixture.
I disassembled the carburetor and did not find any defects that I could detect. I installed a renew kit and I'm ready to retest, but my guess is that I will fail again as I really have not changed anything. Two years ago this carburtor passed emissions with ease.
If anyone has an idea what could be wrong with this Holley, I'm all ears.
Thanks for reading!
I could use some help with mine!
I have a Holley 4160 (vacuum secondaries with non-external adjustable floats). My rig is a 86 F250 4x4 manual transmission with the 460 engine.
I had my truck running real nice I thought. I went in for an emissions test and failed big time. I was way over the limit on HC and CO during the idle test. I passed cruise testing just fine. I talked to a local mechanic and after looking at my results he thought there had to be something wrong with my carburetor to have such high emissions at idle. Something like a sunk float or other defect that would dump in an overly rich fuel/air mixture.
I disassembled the carburetor and did not find any defects that I could detect. I installed a renew kit and I'm ready to retest, but my guess is that I will fail again as I really have not changed anything. Two years ago this carburtor passed emissions with ease.
If anyone has an idea what could be wrong with this Holley, I'm all ears.
Thanks for reading!
Moderator
Joined: Nov 2007
Posts: 22,415
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From: Denver Metro Area, CO
What I found works best for me is to tune/adjust/fiddle while it's hooked up to an exhaust gas
sniffer. Sometimes the slightest little micro-turn of an adjustment screw will affect the readings
in a big way, sometimes intentional vacuum leaks help.
sniffer. Sometimes the slightest little micro-turn of an adjustment screw will affect the readings
in a big way, sometimes intentional vacuum leaks help.
Moderator
Joined: Jan 2001
Posts: 56,984
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From: Virginia
It may be better on emissions if the power valve was leaky, and they are known to leak after they get old. Also turn the idle mixture screws in as far as you can and still have a half-way decent idle.
Post Fiend
Joined: Oct 2003
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From: Western Central NV
Craig
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Tuned
Joined: Jun 2006
Posts: 363
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From: Graham WA
Going to an Emissions Shop ?
I like to resolve my own issues with the help of this forum and friends, but I don't have any way of measuring the results of tuning the idle circuit. So now that the carb is rebuilt and I have set it up and it is running good (incidentally it was running good when it failed test also...:-( ), I'm thinking of turning to a shop with the sniffer to dial it in. The way I dial the idle circuit in is with a vacuum gauge. No other capabilities in my home shop.
PS: My Holley is an after market 4160 (same as 4150 double pumper except with vacuum secondaries) about 3 years old. Certainly should not be warn out with 3k miles or so.
PS: My Holley is an after market 4160 (same as 4150 double pumper except with vacuum secondaries) about 3 years old. Certainly should not be warn out with 3k miles or so.
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Tuned
Joined: Jun 2006
Posts: 363
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From: Graham WA
Big Red went to an emission certified shop today and was dialed in on the sniffer. After that I took her over to the WA Emission Test Site. Passed well clear of the emission limits. Glad to have that behind me and my license up to date. Also, here in WA my truck will be exempt from now on due to age. Won't have to fuss with the testing anymore. Yes!
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Post Fiend
Joined: Oct 2003
Posts: 9,176
Likes: 4
From: Western Central NV
Glad you got it smogged & it passed. So it is a 650 CFM 4160. One less problem. If it is only 3 years old then it has power valve blow-out protection from the factory. Holley added it in 92 or 93.
Craig.
Craig.
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