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Ok, now I need some carb tuning advice (Holley 4160 600CFM)

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Gary Lewis

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

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I sit corrected. Obviously, Holleys are not my forte.

So, Bill, are there idle circuits in the secondaries on his carb?

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

85lebaront2

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

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Maybe and maybe not, I would need the Holley list number and even then without my big Holley book I had at Preston it would be a crap shoot. If there are feed holes and a transition slot in the back side of the throttle body, then it has secondary idle circuits. Holley used them on almost all 4150 and many 4160 series carbs.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Gary Lewis

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

If there are idle circuits would there not also be idle mix screws in the metering block? So, if he has the screws he has idle circuits, and if no screws no idle circuits?

Gary, AKA "Gary fellow": Profile

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

This carb does not have four corner idle adjustment...just the two mix screws in the front. The rear just has a metering plate instead of a metering block. It's this one below...

https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-80457SA

I took a look down the barrels. Can't really see much. The rear barrels are pretty clean and appeared to be more closed than the primaries. Maybe there's something keeping the primary plates open a hair.

I'll investigate a little more tomorrow. I'm done for today. I was tentatively planning to get rid of the Holley anyway and replace it with a Summit M2008 500CFM...

https://www.summitracing.com/parts/sum-m08500vs/overview/

They seem to get rave reviews, but that fuel inlet means I'll have to relocate my coil. Anyway, that's a discussion for another day.

Gotta get the one I have working properly first;).

Thanks guys.

1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

85lebaront2

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

In reply to this post by Gary Lewis

No, the older Holleys have fixed secondary idle circuits, and if you look at the specs on the metering bodies (plate in the rear bowl) they have both main and idle jet sizes specified. Like I said, I miss not having the 3" thick Holley catalog I had at Preston.

Bill AKA "LOBO" Profile

ArdWrknTrk

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

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In reply to this post by Rembrant

The REALLY tricky manifold to head leak is when it's leaking into the lifter valley!

Though that will eventually show as smutty plugs, and you may get knock because one of more cylinders are acting like a diesel.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

ArdWrknTrk wrote

Though that will eventually show as smutty plugs, and you may get knock because one of more cylinders are acting like a diesel.

Well, the good news is that my plugs all look exactly the same and are all pretty clean. As Gary mentioned before, almost too clean. According to my Holley book, they look good. I have since changed them from Autolite 764 (Now obsolete I believe) to Autolite 104 (Same plug I believe, but with full length threads).

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Oh...I should clarify...the truck is working OK, I just think it will work a little better than it does.

Full disclosure...I have a bad habit of chasing ghost issues...that end up being nothing at all, other than me being too fussy about a noise or a vibration or whatever. Still...based on that idle, something isn't quite right, and I'd just like to dial it in a little better, and I think it can be.

Gary Lewis

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

Bill's the guru, but those plugs are awfully white. I would expect a light tan residue on most of them if properly jetted. Or, maybe I should say with the proper AFR.

As for ghosts, the fact that it won't idle down below 750 RPM is not a ghost. You should be able to kill the engine by closing the throttle plates, even when the idle air/fuel mix is spot-on. That says to me that it is getting air somewhere other than the carb.

And I think your new wide-band meter is telling you the same thing, although being new it is suspect. So I'd leave it out of the pic at this point and see if you can figure out if you are getting extra air and where from. Car cleaner!

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

This post was updated on .

If you don't want to get things messy, use a propane torch valve on a low setting and not lit. Carefully aim it an any joint, manifold to head, carburetor mounting, vacuum trees. Unfortunately when everyone went to full numeric plug PNs for ease of computer use they do not mean as much as they used to, on the older numbers, Autolite would be higher numbers were hotter. My truck uses an ASF-42, colder would be ASF-32, resistor plug would be ARSF-42.

The plugs do look lean to me, but depending on the actual heat range that could be misleading.

Here is what I was referring to on the secondary metering bodies: https://www.holley.com/search/?q=Secondary%20metering%20bodies

There used to be a real long list of these as both main and idle jets are in them.

Bill AKA "LOBO" Profile

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

In reply to this post by Gary Lewis

Gary Lewis wrote

You should be able to kill the engine by closing the throttle plates...

Gary,

I took the truck to go see my folks today so I didn't get any troubleshooting done per se...BUT...on two occasions today, I was cruising along one time at maybe 45 mph and another time at 70 mph, and when I pushed the clutch in while slowing down the engine would not idle. I had to feather the throttle a bit to keep it running, and then a minute later it idled just fine again.

Is that a sign of anything related to my idle issue?

Only change made since yesterday was that I dialed the choke back so that it worked again.

Also, I did let the truck warm up using the choke, and still nothing showing up on my AFR gauge. Not a proper test really, as it was a lower RPM choke setting, so I doubt the choke plate was closed all the way.

I'll get some more tests done this week. Thanks guys.

Gary Lewis

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

Did you have the brake on when the engine wouldn't idle? I'm wondering if the vacuum booster has a split in it. Sometimes it seals and sometimes it doesn't?

Gary, AKA "Gary fellow": Profile

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Gary Lewis wrote

Did you have the brake on when the engine wouldn't idle? I'm wondering if the vacuum booster has a split in it. Sometimes it seals and sometimes it doesn't?

That's possible Gary. I just tried the booster using a Mitivac and it holds 20" vacuum no problem, and seems to hold when you push the brake pedal, but something weird could be happening when it gets warmed up. I kind of dismissed the booster because I noticed last week that it was holding vacuum OK, but maybe tomorrow I'll actually plug the line to the carb as a more definitive test. Thanks for the idea.

I'll be doing some more vacuum leak checks this week.

It's weird...the AFR gauge seems to work for about 15-20 seconds on start-up, then the numbers rapidly ramp up and the gauge flatlines. I haven't ruled out a bad gauge either though, so that is possible as well.

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

In reply to this post by Gary Lewis

Ok, so I'm back with some news and test results...

After doing some of the suggested tests of covering the carb up and restricting air flow, I brought the truck close to stalling several times and I actually did stall it once. AFR gauge didn't budge. Upon start up, the gauge actually reads pretty good...13.5 AFR, sometimes 14:1, etc, and then it rapidly runs up and pegs full lean and stays there. Meanwhile you can smell the stink of fuel...

Anyway, fully convinced at this point it's the gauge, I called AEM tech support and they were super helpful. When I explained what the gauge was doing, he immediately asked for the serial number on the back. Once I gave him the number, he confirmed that my gauge is one of a batch of known faulty gauges...in which the issue is exactly what mine is doing, pegging full lean. They're going to send me a new kit asap.

As for the vacuum leak diagnosis, still nothing yet. I tried with my cylinder of MAP gas going all around the carb, the base of the carb, spacer, back and forth left and right the full length of the intake manifold to cylinder head seam, and nothing, anywhere.

So I'll have to keep hunting. If by chance it's sucking from the lifter valley, I guess there's no way to know without pulling the intake? I've restricted the flow into the carb, and the truck stalls.

One observation...and one of you carb guys can tell me if this is OK or not, but with the truck idling, if I cover ONLY the secondaries and close them off, the engine will stall. I thought the thing would breath enough through the primaries...but apparently not?

85lebaront2

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

If it is pulling from the bottom of the intake ports, you will have a lot of vacuum on the crankcase pull the PCV valve out and plug that opening in the valve cover, on the other side, remove the breather cap and try covering the hole with the engine running, normal result will be a gradual pressure buildup, if you have a vacuum under these conditions the intake gasket is leaking around the ports.

Bill AKA "LOBO" Profile

Rembrant

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Ok, so I finally got back at this today (briefly). I plugged the PCV valve hole, and then covered the oil filler hole with my hand (with a thin leather glove on) and there was indeed a gradual pressure build up. No vacuum of any kind.

According to my vacuum gauge, which is by no means a precision instrument, I'm pulling 18" vacuum at idle. That is about the best that I've gotten with it. I seem to recall this being the best vacuum we were able to achieve on the dyno day as well, but my memory could be fuzzy on the topic.

The idle speed screw is backed out all the way, and the idle is currently at about 840/850 RPM.

I can't find a vacuum leak anywhere. I plugged everything. I've gone around and around with MAP gas spraying on the carb and intake, etc. I plugged the brake booster vacuum line, and it was fine...nothing changed. The only thing that pulls the idle down a little bit is plugging the PCV valve...which I assume is normal? Isn't the PCV valve a controlled vacuum leak of sorts?

So...I guess this means I'm back to suspecting the carb again...and the primary or secondary plates not closing properly.

With the idle speed screw backed out all the way and with maybe a 1mm gap (0.040"), I can actually close the throttle a little more manually...and the idle does drop a little bit...but I don't want to force it any harder than I have been. I don't know what stops the primary throttle plates travel when they're not hitting the idle speed screw. I seem to recall there being an adjustable stop in there, only accessible from the under side of the carb...one of those things that is "factory set"...

Anyway...my new O2 sensor kit shows up on Tuesday and will take all of 5 minutes to install, so I'll finally be able to see what's going on with this thing...at least in how it's breathing anyway.

Stay tuned.

Gary Lewis

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

It does point to the carb. I don't think there's another stop for the throttle, although I've proven that I don't know much about a Holley, so maybe there is.

But the plates are supposed to be aligned on the shafts from the factory so both of them close well. However, if you are able to turn the shaft a bit more and get the idle to come down I'm guessing that one of the throttle plates is misaligned and stopping the other one from closing.

I don't recommend this as everything I've read says you shouldn't do it. But I've taken the screws out and put them back on many carbs and have gotten the throttle plates aligned nicely each time. However, you don't need to completely remove the screws or plates. You should be able to loosen the screws and shift the plates around to get them to close better or evenly. But the screws are probably staked such that you can't remove them w/o grinding them off - or risk breaking them off. So be careful.

Anyway, with the idle at ~850 something's wrong and you've pretty much proven that there's no vacuum leak.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

If the throttle plates have shifted, the easiest way to check everything on a Holley is to actually remove the throttle body. With the throttle body removed, hold it up to the light so you can see if the throttle plates look even in the holes.

If they do not, first remove the secondary closing link (J shaped link on the linkage side), with it off and the idle stop screw backed off so it isn't touching, carefully loosen each of the 4 screws on the primary throttle plates. move the shaft slightly side to side to find the centered position. Holding the shaft in the closed position, tighten the screws (I usually press the throttle plates closed and tighten the screws. Recheck the throttle plates against the light, if there is a difference, your throttle shaft may be twisted.

On the secondaries, if you do not want to mess with the stop screw, remove the lever the secondary diaphragm connects to, this will allow the plates to fully close. Repeat what was done on the primaries to align the secondaries.

While you have the throttle body off, take a picture of the top side for Gary, so he can see the idle circuits.

After both sets of throttles are centered and tightened, reinstall the closing link, it should just push the secondaries closed when the primaries are closed. When you reassemble the carburetor, make sure that the secondary diaphragm does fully close the throttles, if not either it is the wrong part (there are two different lengths) or it is assembled wrong (pain it the rear to get right sometimes).

If you want a "sanity check" on the secondaries, with the choke and primary throttles open, blow compressed air down the passenger side primary venturii. If everything is right, the secondaries will open. If your carb has an additional hole in passenger side rear venturii, they may not open fully as it will bleed part of the vacuum signal. It is to "accelerate" the secondary opening once there is enough air flow. Some Holleys have it and some don't.

Bill AKA "LOBO" Profile

grumpin

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Dang Bill! I’m sure you’ve forgotten more about carbs than I dare say I know!

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

85lebaront2

Re: Ok, now I need some carb tuning advice (Holley 4160 600CFM)

Administrator

That might be true. Preston Carburetion was a Holley Warranty Center, and we also sold Rochester, Stromberg, Carter and Weber carbs. There is one book I would love to find a copy of, it was a book put out by Weber, titled "Technical Introduction to the Master Catalog" It explained in great detail how each part of the metering circuits, both idle and main along with transition circuits functioned. I haven't been able to find one anywhere.

Bill AKA "LOBO" Profile

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