Reversing Holley "reverse-idle", and...

[erratic50]

Nice!

[Walking-Tall]

Thanks!

[Walking-Tall]

... went to a fellow today who's gonna put it on a '71 350 V8 Vega

[prp1470]

I'm not at all sure how posting a reply works. This is my first (and only) forum membership, and my first try at a posting. My question is have you ever employed this method on a Spread Bore, such as a List 9895? I'm attempting to develop a Q-Jet replacement based on a Holley. The first step is altering the idle logic per your method, followed by machining for, and installing, annular boosters, replaceable air corrector jets, replaceable bleed metering blocks, center-hung bowls, re-chromate, and tune. I have two mules: a warmed 305 SBC, and a slightly more wild 413 SBC. Do you have any experience with annular boosters, especially used in a vacuum secondary carb? Do you have any experience with spread bores?

Thanks for your detailed posting of reversing the reverse idle. Much appreciated. I want to acknowledge your technique but all I can say is "per Walking Tall of FEP". If that's okay, I'm okay with it. I want to do something, but not sure how to proceed.

[prp1470]

(I'm new - learning how to post)

[qikgts]

Welcome to the site!

Mike (Walking-Tall) doesn't post every day so don't fret if it takes a few days to get a response. I'm sure he will reply at some point.

[prp1470]

Glad to be here. Also glad that my post went through. As you can see I sorta flubbed it up (my first time).

[Walking-Tall]

I'm not at all sure how posting a reply works. This is my first (and only) forum membership, and my first try at a posting. My question is have you ever employed this method on a Spread Bore, such as a List 9895? I'm attempting to develop a Q-Jet replacement based on a Holley. The first step is altering the idle logic per your method, followed by machining for, and installing, annular boosters, replaceable air corrector jets, replaceable bleed metering blocks, center-hung bowls, re-chromate, and tune. I have two mules: a warmed 305 SBC, and a slightly more wild 413 SBC. Do you have any experience with annular boosters, especially used in a vacuum secondary carb? Do you have any experience with spread bores?

Thanks for your detailed posting of reversing the reverse idle. Much appreciated. I want to acknowledge your technique but all I can say is "per Walking Tall of FEP". If that's okay, I'm okay with it. I want to do something, but not sure how to proceed.

You did fine. Welcome to the site

No, not with a 9895, but yes with a 7002-1. There are a number that have "reverse-idle", and the steps to eliminating it are the same as you see earlier in this thread. If the original primary metering block's passages where the idle mixture needles reside are in the neighborhood of 0.0625", they're use-able with regular sharper tipped mixture screws, otherwise, yes, contrary to common belief, regular Holley metering blocks and float bowls can go onto them. Not a whole lot of experience with annular boosters, besides dealing with carburetors that already have them. I've built a number of good working 4165 & 4175 spread bores so far, yes.

Quite welcome. Thank you for the questions, and my name is Mike, and I don't need any acknowledgement/credit, if that's what you mean. You can if you want, but the information is shared gladly and freely for anybody who wants to learn and do-it-yourself. Send anybody who's curious or that you want to to this thread if you want... and any further questions, fire away

[erratic50]

.....

[prp1470]

Hi Mike. My criteria for spread bore selection included: 1. 650 CFM (or thereabouts), 2. Vacuum secondary (4175), 3, Provision for electric choke, and 4. Throttle lever similar to 3310/4780. List 9895 seems to fit the best. Cores are available fairly reasonable. I found your posting on reversing the “Reverse Idle”, and boom, I was off to the races. I wanted to use aftermarket metering blocks with replaceable emulsion bleeds, and replaceable IFR and PVCR. The accelerator pump transfer tube was a problem, but you showed a technique for eliminating it with JB Weld. Boom again. I wanted to use center-hung fuel bowls. Not a problem with aftermarket metering blocks. Actually there seems to be a problem with the 4175/4165 fuel bowls anyway. The accelerator pump passage from those fuel bowls doesn’t match up very well with “rest of the world” metering blocks. Like the spread bores weren’t odd-ball enough. Holley for some reason designed spread bore fuel bowls to be incompatible. I find it curious. But the 9895 presents another problem. Cast-in, non-replaceable boosters. Seems to be a universal problem with all spread bores, not just 9895. I’ve seen some square bores with cast-in boosters, too. I’ve got three options: 1. Leave it alone, and use-as-is (like that’s gonna happen!!), 2. Machine a step in the cast-in booster (not much signal gain, but better atomization), or 3. Develop a machining technique to install replaceable boosters. In a nutshell, I cut-off the existing cast booster, back spot-face a 3/8” seat for the new booster, alter the new booster rectangular seat to fit the round 3/8” spot-face, enlarge the booster feed channel for the 5/16” booster tube, and finally, machine the booster feed channel inlet to allow a swage. The new replaceable booster is then installed just like any other replaceable booster. The technique is applicable to any Holley with cast-in boosters. I’m currently making two 9895’s. One with .600” I.D. annular boosters, and the other with .500” I.D. annular boosters. We’ll see how difficult (or easy) they are to tune, and what the difference is in performance. I’ll post photos and description. What do you think? Paul

[Walking-Tall]

Hi Paul,

Actually, since doing the one you saw with a large load of jb-weld up there earlier in the thread... easier, maybe better, and highly effective, is jb-welding-ing a short length of 1/4" steel tubing into the body's accelerator pump counter-bore, so it ends up sitting flush with the body's metering block face or say 0.005" above for good gasket squish and seal, is what I do with such carburetors since.

The problem I have with 4165/4175 float bowls is the absence of externally-adjustable needles and seats, lol!

As far as I'm aware, all of the Holley spread bores have boosters cast with the body, because they are on the angles that they are... and yes, I've seen and dealt with some factory '60's and early '70's Chrysler square bore Holley 4-barrels with cast in boosters... by plugging their kill bleeds, upside or downside, with jb-weld, and then tuning them like any other...

You're more ambitious than I am, lol... I don't have the machining ability though, to be machining out boosters and adding others... are you talking mostly about annulars out back? ... because, in a vacuum secondary, annulars out back really wouldn't make a whole lot of difference in my opinion... up front, maybe, but with the small primaries already being so sensitive and responsive... I dunno, it's your party, lol... I wouldn't bother...

Yes please with the photos and descriptions

[prp1470]

The first time I saw your post describing the JB Weld technique, the thought occurred to me that the little brass transfer tube might be utilized somehow to interface with the metering block. Machine it off shorter (plus a little bit for gasket squish), possibly enlarging the passage somewhat. But then I thought you’d already developed the JB Weld method, it looked pretty foolproof, pretty easy. I couldn’t see any reason why it shouldn’t work just fine, so I went ahead and did it the JB Weld way. And sure enough, it worked just fine. I may pursue the tube method. We’ll see.
I’m currently using two shop queens to hack up. A List 6210 (4165 double pump spread bore), and a List 6160 (vacuum secondary square bore). Both of course have cast-in boosters. The back spot face cutter I’m using came from Travers Tool, and is pretty cheap. The 3/8” cutter (HHS) is about $25, and the 3/16” mandrel is about $10. I just chuck the mandrel in a hand drill and pull. Not particularly high tech. The cutter as furnished is not very aggressive. It’s really just a spot face cutter, not meant to remove lots of material. I’ve ground additional back relief to make the cutter more of a mill cutter. It’s now lots more aggressive. The trick is to remove as much material as I can using a burr, prior to spot facing. The primary side has to be recessed quite a bit, requiring removal of much more material using the cutter. The secondary side is really not much more that an actual spot face. Boosters that come in various (shorter) leg lengths would be useful.
I, too, don’t know how much, if any, advantage annular boosters might yield. David Vizard says it’s a good thing. I’m doing this mostly just to see for myself, and of course, just to see if I can.

[Walking-Tall]

Sounds like a bunch of perfection going on over there

[prp1470]

I see the photos of your beautiful carbs and notice that they are “silver with gold fittings”. Do you do your own zinc plating, and then polish? The gold fittings are all the same color, so they can’t all be polished brass. Throttle levers, for example, are steel. Are you re-plating the fittings? Whatever you’re doing they sure are great looking. I’m soda-blasting, re-zinc plating, and re-chromate finishing. I originally accidentally left them in the zinc a little too long, followed by leaving them in the chromate a little too long. Both predictable beginner mistakes. The result, as you’d expect” was a darker color than “factory”. The red anodized metering blocks and fittings look pretty good with the darker color, so I don’t see the need right now to strip off the plating and re-do. With experience I suspect the result will be lighter. Just wondering what you do.

[Walking-Tall]

I wish I could say there was some kind of correct refinishing of things going on here... what you see are mostly older castings with most or all of the original finish gone, cleaned up real well, and shot with a bit of silver/gold and then clear lacquer... which, with ethanol in gas now, isn't completely impervious to gasoline anymore, but prevents old castings with no finish left from oxidizing to a white powdery kinda stuff... so yeah, that's all I'm doing. Thanks for noticing. I try to do as well a job as possible... unlike some units I've seen that somebody obviously dunked the whole things into a bucket of paint, LOL!

[prp1470]

Hadn’t thought of silver & gold spray followed by clear. Absolutely beautiful, except for E85. That could be a deal breaker. For a Fuel-proof clear I’ve found Klass Kote 2-part epoxy works pretty well. Equal parts Klass Kote #40 (part A) and Klass Kote 405 (part B). Can be reduced with Klass Kote 500. Notice all “parts” are named Klass Kote ($$$). Gotcha! If you want to venture into re-finishing, the initial cost isn’t all that much. I already had a cheap blaster (Harbor Freight). Big boxes of baking soda at Walmart (or Dollar General) are cheap. And for small carb-size pieces, your compressor you probably already have is adequate. I wouldn’t get into full scale production work with these units, but for a few carbs, it works fine. The chemicals aren’t too expensive either. I would recommend a variable DC power supply ($40) on EBay. I tried to rig a 3volt DC supply using a D-cell pack. No amperage control. The result was unacceptable. Lots of instructional internet videos for info. Be glad to share the details of what I’m using. I’m just starting out.

[Walking-Tall]

I'd be glad to see what you're doing.

[Walking-Tall]

Pardon the repetition, but I believe the following is useful to be posted in numerous places...

A shamefully ridiculous example of why I tell folks in regard to Holley carburetors, "if you want a good one, get an old one":


Posted at racingfuelsystems forum, entitled "Brand New Blunder #??? - A Heads Up..."

"So a local (repeat client) fellow contacted me asking if I could fine tune his brand new spread bore vacuum secondary... that with a few miles of driving his '77 Malibu he found that it would hesitate upon light part throttle "tip in"...

Observation #1 was a throttle lever bent over toward the main body badly, so badly that it was bent all the way down to the throttle shaft area and loose on the throttle shaft, obviously dropped before it went into the box, and bumping into the driver's side secondary link lever at wide open throttle as well... and a secondary stop bracket not allowing full wide open of the secondary throttle plates... idle screw backed out, fully shut primary throttle plates, he said still idled way too fast, primary lever and idle screw tip not even inline with each other (primary throttle shaft not fully installed/seated laterally originally), and quite open secondary throttle blades...

Observation #2 was small appearing primary idle air bleeds, and large idle mixture passages and blunt-tipped idle mixture screws... so I told him it is a "reverse-idle" unit, and it'll have passage holes into the primary bores, blah blah blah how "reverse-idle" works etc... I don't remember where now, but online somewhere that sells these states that the 80555-1 4175 650 spread bore vacuum secondary has a "forward" idle circuit... I presume as opposed to "reverse"?... hmmm, okay...

Observation #3 was NO holes/passages into the primary bores for "reverse-idle"... so, in a nutshell, it has standard idle main body and base plate, and a "reverse-idle" primary metering block and mixture screws... at first I got him back here and showed him all of their "quality control" and "attention to detail", and thought completing "reverse-idle" would be the best course of action to make it behave... but after some more thought about it, I decided against that, because it would mean blocking the large standard idle discharge holes in the base plate, drilling new small ??? size constant idle feed holes below the primary transfer slots, and drilling ??? size passage holes into the main body... so instead I drilled the idle mixture screw passages in the PMB with a #29 drill, tapped 8-32 thread on through the passage, and installed 8-32x1/8" brass socket set screws with 1/16" holes in them, so that regular sharp tip idle mixture screws can be used...

Observation #4 was air bleed sizes crazy in contrast to the handful of these (other, older, LIST-7002 etc.) that I have dealt with before, as well as somewhat larger than usual primary idle feed restrictions at 0.029"... and #64 primary jets where #62's are supposed to be according to documentation...

Here are it's original calibration details as I found/measured:
- 0.029" PIFR's (?) & 0.035" SIFR's (#54 SMP - specs not listed anywhere btw)
- 0.053" PIAB's (?) & 0.051" SIAB's (?)
- 0.036" PMAB's & 0.040" SMAB's (?!)
- #64 PMJ's (?) & 0.081" secondary main circuit holes (#54 SMP - specs not listed anywhere btw)
- 0.057" PVCR's
- 0.040" pump shooter (?!) and orange pump cam in position 2

So I remedied the metering block like explained above, loosened throttle blade screws and shuffled shafts and blades around so they were correct, got out the brass and drills and created 6-32x1/8" 0.026" PIFR's (very mild stock replacement camshaft in rebuilt 350) and installed those in the block, installed #62 PMJ's, drilled and tapped and installed 10-32x3/16" 0.070" PIAB's, 6-32x1/8" (the secondary constant idle feed holes seemed a bit big at about 0.030", so I chose to create) 0.040" SIAB's and 6-32x1/8" 0.026" SMAB's, and installed new regular idle mixture screws and the orange pump cam in position 1... not having any "anti-pullover" shooters of other/smaller sizes on hand, the rather large 0.040" remains in it...

A couple hours after picking it up, he was back at the door, beaming and grinning, telling me to come check out my handy work. He brought the car, and it was idling in the driveway slowly and nice and smooth, and he said it's working night and day real nice, and making far more sense setting idle speed and mixture... and when he left here, it launched real good, barking out the exhaust, lifting the nose of the car some and was off down the street, lol!

Thought I'd share this with you guys who may end up dealing with one of these further enhanced (translation: EFFED UP) versions of the "new and improved" that come brand spankin' new outta that place and cost this fellow 750 smackers... for what? Nearly complete re-calibration necessary so that it will just FUNCTION correctly... pardon my french, but the pompous jackasses who apparently know-it-all really should be knocked down a few notches somehow... I wish..."

So yeah, the moral of the story... stop buying expensive new garbage from giant monopolizing corporations, because contrary to their marketing and such, they do not know WTF they are talking about or doing there at all anymore.

[erratic50]

Seems like their marketing department is still in full swing relying upon the reputation their company built. Be it on the backs of hard working engineers who were shown the door years ago. The guys (damn it, not calling them engineers) that remaining can barely spell the part names let alone make good decisions about sizing.

And let's face it -- its all in the interest of selling a $2000.00 EFI system instead of a $750 carb.

When the time comes (soon) we should collaborate on a carb for my 353, Mike. I know Edelbrock is not your favorite but its what I have and think I'd like to run after a proper rebuild.

[Walking-Tall]

James, you and I are completely on the same page. If little ole me can look back at the handful of similar carburetors I have dealt with and clearly see where things are jacked up in something new, why can they not? Too big for their boots, I say, they simply refuse to or don't care to.

Edelbrock's are fine. My preference for Holley is about their pure simplicity and that I've come to learn them inside and out. I've now dealt with a number of much scarier/complicated carburetors... and like I tell folks when they approach me with something I've never dealt with before... the end result function isn't different between them, only the differing ways they go about arriving at the same results, and that a carburetor is a carburetor is a carburetor. If I recall right, you've got the 750 Edelbrock that's got boosters a little too short for proper main signal function in conjunction with float level... which I'd imagine is an easy enough fix to press on some short lengths of thin brass tubing (probably with some smoothed jb-weld too so they stay put) with an inside diameter the same as the booster's outside diameter so that they reach down to the venturi area airflow for their signal where they should be. Hit me up with a PM or the email function when you'd like to do something.

[clanceman427]

Hi, I’m new here and fascinated by this thread. I too have a reverse idle carb that I am working on and I have a lot of questions. It’s a 4165 List 6772 so it’s a spread bore 650 double pumper with mechanical secondaries and reverse idle setup. Is it ok if I share questions and photos on your thread here? I love all the nuances of getting carbs to run right!

[Walking-Tall]

Hello clanceman427. By all means, ask away and share away

[CC1991]

Hey guys, I'm new to the forum and to be perfectly honest, it was this thread that caught my attention. I can't claim to own a fox body, but I do have Ford 351W in a ski boat with a Holley that is doing my head in - the discussion about the reverse idle is really interesting, and I haven't found the kind of info this forum has anywhere else!

Mike, I may have an interesting challenge for you, do you mind if I fire some questions at you??

[Walking-Tall]

Hey guys, I'm new to the forum and to be perfectly honest, it was this thread that caught my attention. I can't claim to own a fox body, but I do have Ford 351W in a ski boat with a Holley that is doing my head in - the discussion about the reverse idle is really interesting, and I haven't found the kind of info this forum has anywhere else!

Mike, I may have an interesting challenge for you, do you mind if I fire some questions at you??

Bring it, fire away

[CC1991]

Legend, thanks Mike!

Ok, so the carb I've got is a 4bbl square bore 600cfm with vac secondaries, list 50469-1. I guess that's basically a 4160, but marinized with the non-externally adjustable side hung floats etc.

I think someone has messed with it or re-built it in the past, but I can't tell if it's had parts swapped on it. The thing that's baffling me is the idle circuit seems to be a mixture of reverse and normal! So the main body has the cross drilled holes (they were referred to as auxiliary air bleeds) into the primary bores you showed on the reverse idle carb. But the metering block has conventional idle screws that adjust richer anti-clockwise and leaner clockwise. The main body doesn't have the brass plug blocking off the normal idle passage that you showed on the reverse idle carb, and the throttle plate has the normal transition slot and separate idle passage below the throttle butterflies.

Here's the final kicker - the metering block doesn't appear to have idle feed restrictors. The holes at the top and bottom (I checked both locations) of the idle well are large, like 0.12". I can't see any restriction on the idle well other than the needles, even if I poke a thick wire into the passages.

I can only assume the "auxiliary air bleed" holes leading into the primary bores are calibrated to work with the regular air bleeds and the wide open idle feed passages to arrive at a normal idle mixture, but I've never seen a system like this.

The odd thing is it works - I'm chasing lean idle issues at the moment which is why I'm now looking closely at everything, but the carb has been like this for the 9 years I've had it, and when the boat's running well the idle screws do exactly what they should - they'll kill the engine if I seat them, and the engine wants about 1.75 turns to idle nicely.

Have you ever seen an idle circuit like this? Do you think my conclusion about how it works is right? I could plug those bleeds in the primary bores and install IFRs, but this system seems to work.