backward Holley issues
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Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
backward Holley issues
When I changed from an auto to manual trans, I turned the 4160 Holley 1848 so that the primaries are facing the firewall. Rather than circle my long throttle cable around the carb 360*, this seemed the solution. This way the cable loops around the front of the v.cover. But, since changing the trans, I have a terrible stumble when taking off from a stop. I thought it the acc. pump nozzle or the acc. pump cam to a lesser degree. However, I began with .034 nozzle and went up to .038, and that was much worse. So I began going down in nozzle size in increments. But now I'm all the way down to .021, with the mildest cam, and the stumble is nearly gone. The smallest nozzle made is .018, and I'm about to try it., but I can't help but wonder if there is more going on here than the nozzle size. Is it possible that due to the configuration of the carb, on take off the fuel is pushed away from the jets? Is that possible at idle with the bowl full??
Post Fiend
Joined: Apr 2002
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From: Waterloo, Iowa
Jets have nothing to do with that, it's strictly the idle circuit and transition circuit, just off idle. And the squirters, of course. You could actually remove the jets entirely and drive around the block. That's why carb setup and idle mixture adjustment is so important, vacuum leaks, etc most driving on the street is done at idle or just off idle. Jetting is misunderstood!
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Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
It just seemed as though I was dialing down the nozzle size an awful lot, so I began to wonder if something else was going on. I need to hook up the A/F ratio gauge so I can properly tune/check it. To go from .034 nozzles with a c6 to .018 with a manual seems rather extreme.
Moderator
Joined: Dec 2007
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From: Boise, Idaho
It definitely seems like that's a really tiny squirter. I've never had to go below a 0.030 on any of mine to get it in right.
As Tedster says, your idle circuit has a lot to do with your off-idle acceleration as well. I really wish it wasn't called the "idle circuit", as that causes a lot of misconception about how it's used and what it does. It sounds like it's just exactly that. Idling.
But it is also for low RPM cruising, acceleration, etc.
You can try richening up the idle a little bit to see if that helps fill that too.
Your AFR gauge can help a lot since you can see what the numbers are doing.
As Tedster says, your idle circuit has a lot to do with your off-idle acceleration as well. I really wish it wasn't called the "idle circuit", as that causes a lot of misconception about how it's used and what it does. It sounds like it's just exactly that. Idling.
But it is also for low RPM cruising, acceleration, etc.
You can try richening up the idle a little bit to see if that helps fill that too.
Your AFR gauge can help a lot since you can see what the numbers are doing.
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Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
Thanks, AB. I found that only one side of my squirter is squirting! Before I remove it, I'll run a tiny wire through it to dislodge any foreign matter. I did ck it prior to installation. I'm sure that with both sides squirting it will run just a tab better 
I'm spending the day with the carb, and should have the A/F/R gauge connected today. Should it come to that, I may pull the carb and drain it and blow through all the orifices. I should have done that when I freshened it up after its four month lay-off.
I'm spending the day with the carb, and should have the A/F/R gauge connected today. Should it come to that, I may pull the carb and drain it and blow through all the orifices. I should have done that when I freshened it up after its four month lay-off.
Postmaster
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From: Spokane, WA
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Moderator
Joined: Dec 2007
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From: Boise, Idaho
I've done that before, and had a carb gummed up. It ran fine, but there were "issues" I couldn't figure out. Best thing I did was get a can of compressed carb cleaner with the straw, take the fuel bowls off, and blast through every opening. The 8 air bleeds in particular. I had 2 - 3 of them that took a few blasts until it sprayed through. Made a big difference.
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Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
I really wish it wasn't called the "idle circuit", as that causes a lot of misconception about how it's used and what it does. It sounds like it's just exactly that. Idling.But it is also for low RPM cruising, acceleration, etc. Your AFR gauge can help a lot since you can see what the numbers are doing.
Moderator
Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
I've read that too. I think it completely depends on how much air is moving through the carb. So, higher RPMs and harder acceleration are going to start to get into the jets and power valve.
If you're cruising at 40mph at 1500 RPMs, I think it's very possible you could be cruising just on the idle circuit.
If you're flooring it at 5000, you've got the jets and power valve involved too, as well as secondaries if you have them.
If you're cruising at 40mph at 1500 RPMs, I think it's very possible you could be cruising just on the idle circuit.
If you're flooring it at 5000, you've got the jets and power valve involved too, as well as secondaries if you have them.
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Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
What a difference a well-working carb makes! I finally had to take things apart and clean a bit. Then, I was able to get both sides of the nozzle to squirt. Imagine that. It is almost impossible to stall the engine from a start now.
The thing is that sometimes the 'growl' is terrible. I was under the truck when it was running and it sounded like a loud diesel, and that sound was coming from the trans! I jumped in and pressed on the clutch, trans in neutral, and the noise vanished. Let out the clutch and the noise was gone. Gremlins.
AB, you nailed it with the squirter size: .031, with a mid-range cam, red.
The thing is that sometimes the 'growl' is terrible. I was under the truck when it was running and it sounded like a loud diesel, and that sound was coming from the trans! I jumped in and pressed on the clutch, trans in neutral, and the noise vanished. Let out the clutch and the noise was gone. Gremlins.
AB, you nailed it with the squirter size: .031, with a mid-range cam, red.
Moderator
Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
Awesome! Glad to hear that helped a lot. I'm guessing that even though the 0.031" with both squirters working is better than a 0.021" with only one side working (even though the 31 is putting in more gas) is because all of the gas coming out of the 21 was only going through one barrel, and making the mixture screwy with one side putting in lean fuel and the other side overly rich fuel and not properly atomizing. Just a guess though. 
Still odd about the transmission growl. Although, now that you've been discussing it, I've noticed it a lot more with mine. I was always worried it was engine noise. It's put my mind at ease a lot with those odd sounds.
Still odd about the transmission growl. Although, now that you've been discussing it, I've noticed it a lot more with mine. I was always worried it was engine noise. It's put my mind at ease a lot with those odd sounds.
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Lead Driver
Joined: Mar 2008
Posts: 7,188
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From: Near Los Angeles
Awesome! Glad to hear that helped a lot. I'm guessing that even though the 0.031" with both squirters working is better than a 0.021" with only one side working (even though the 31 is putting in more gas) is because all of the gas coming out of the 21 was only going through one barrel, and making the mixture screwy with one side putting in lean fuel and the other side overly rich fuel and not properly atomizing. Just a guess though.
Still odd about the transmission growl. Although, now that you've been discussing it, I've noticed it a lot more with mine. I was always worried it was engine noise. It's put my mind at ease a lot with those odd sounds.
Still odd about the transmission growl. Although, now that you've been discussing it, I've noticed it a lot more with mine. I was always worried it was engine noise. It's put my mind at ease a lot with those odd sounds.
Maybe that was for Diesel models?
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Yeah, that's what it looks like. I was looking at RockAuto and under the 1994 F-350 4.9 flywheel, there were just a few options. Under the 7.3 diesel, there's lots of flywheels with notes about "dual mass", or "solid flywheel option", etc.
Tuned
Joined: Mar 2004
Posts: 412
Likes: 3
I've read that too. I think it completely depends on how much air is moving through the carb. So, higher RPMs and harder acceleration are going to start to get into the jets and power valve.
If you're cruising at 40mph at 1500 RPMs, I think it's very possible you could be cruising just on the idle circuit.
If you're flooring it at 5000, you've got the jets and power valve involved too, as well as secondaries if you have them.
If you're cruising at 40mph at 1500 RPMs, I think it's very possible you could be cruising just on the idle circuit.
If you're flooring it at 5000, you've got the jets and power valve involved too, as well as secondaries if you have them.
It definitely seems like that's a really tiny squirter. I've never had to go below a 0.030 on any of mine to get it in right.
As Tedster says, your idle circuit has a lot to do with your off-idle acceleration as well. I really wish it wasn't called the "idle circuit", as that causes a lot of misconception about how it's used and what it does. It sounds like it's just exactly that. Idling.
But it is also for low RPM cruising, acceleration, etc.
You can try richening up the idle a little bit to see if that helps fill that too.
Your AFR gauge can help a lot since you can see what the numbers are doing.
As Tedster says, your idle circuit has a lot to do with your off-idle acceleration as well. I really wish it wasn't called the "idle circuit", as that causes a lot of misconception about how it's used and what it does. It sounds like it's just exactly that. Idling.
But it is also for low RPM cruising, acceleration, etc.
You can try richening up the idle a little bit to see if that helps fill that too.
Your AFR gauge can help a lot since you can see what the numbers are doing.
Don't confuse the idle circuit with the transition circuit. Yes -- toying with the transition (IAB's and IFR's) will correspondingly affect the idle circuit, but it is realigned back to normal (with reasonable changes) with the idle screws which do not affect the transition circuit and have very little, if any effect on putting around with any throttle input. Essentially, if you are touching the throttle, you are in the transition circuit not the idle circuit. ONLY richen or lean out the idle screws for idle! Using these to accommodate a lean tip in or bucky/lean low rpm driving is basically making a rich surplus at idle for a crutch and really won't help but the smallest of issues.
FWIW my 390 I am clear down to a .025" squirter. Common advice I see in forums is to enlarge squirter sizes to fix that lean spot and this is often not what the car needs. Rather it needs bigger IFR orifices or smaller IAB's. The difference between the 2 changes can be fleshed out by keeping tabs on low rpm (1000-1500) cruising around town with LIGHT tip ins vs mashing it from stoplights.