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Old 09-15-14, 08:17AM   #1
Zedo
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Default Holley 1150 Dominator 9377 3 circuit to 2 circuit opinions needed

I have an old Holley 9377 given to me free 20 years ago. the carb was bought new around 1990. it gave the owner fits and flooded constantly and fouled the plugs all the time.

this is the one that had the warped main body metering block surfaces from the factory, I had to machine/file flat to get it to stop leaking gas into the primaries. Holley had a QC problem where the new gaskets would "pillow" these warped main bodies and they'd run for a week or two when new ok, then as the gasket got compressed would start leaking.

this carb has no power valve provision, the PV threaded hole is completely absent. what is has is a 3rd circuit called the intermediate idle circuit, with an extra drilled hole to feed just that passage with fuel. this is above the curb idle discharge hole and off idle slot in the bores of the carb. there are 4 of these intermediate idle discharge ?????, one for each barrel

these carbs were originally designed for 2-4 applications or for an IR independent runner intake, they were never designed for single 4 application.

I'd like to convert the carb to the old style conventional 2 circuit Holley metering block design. this eliminates the intermediate idle discharge ????? altogether, so all the metering on power and WOT is done only by the main system boosters. (the big rings up top in the middle of the bores)

has anyone done it ? I hear varying approaches i.e. change the metering blocks to standard ones from a 4150. or, use a gasket that blocks the intermediate idle port while using the same blocks it came with. or, put lead split shot fishing sinkers in the discharge port ????? to just block them. (that last idea actually came right from Holley tech service)

looking at the carb, what is really needed there is another idle mix screw to adjust that intermediate idle fuel port. that would mean drilling/tapping and risking ruining the carb though.

what say you ?
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Old 09-15-14, 08:41PM   #2
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I found this on another site and it's ingenius. this guy bevels the edge of the throttle plate to direct airflow away from the intermediate circuit nozzle so it draws less fuel, and that leans it out. if that works it would be a simple fix



Postby RayJE Carburetors » Wed Jul 16, 2008 7:30 am

The part throttle richness problem is a problem for std out of the box holley dominators ...and the bolt together "custom" carbs that are out there .........with proper positioning of the aspirator tube for the intermediate circuit and machining direction vane on the butterfly near the edge of the aspirator tube .. the part throttle richness thats common can be eliminated........

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Postby andyf » Wed Jul 16, 2008 12:44 pm
I don't think I've seen anyone machine the throttle blade as a fix for part throttle AF ratio. Do you have a picture you can post of that operation?



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RayJE Carburetors » Wed Jul 16, 2008 5:30 pm

adjacent to the aspirator tube the blade is machined with a beveled edge so that as the throttle position opens it is directing air to the back side of the blade and not across the opening of the aspirator tube.

the chamfer to a point directly in line with the aspirator tube and about 5/16 wide fans the air to the inside of the blade..and not on the outside and across the outlet of the aspirator....

i dont have any pics to show at moment ..... the ones i do all go out the door as i make the blades to suit
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Old 09-15-14, 08:43PM   #3
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now this is an interesting reply:

One of the best out of the box Dominators is the non-HP 9375, and a few others here have had similar results. The one I have came from Holley without the intermediate bleeds altogether. That would render the third circuit almost useless. Makes you wonder why that carb works so well...
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Old 09-15-14, 11:15PM   #4
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The HP 9375 is a good carb, the other one..well don't waste your time.
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Old 09-16-14, 05:24PM   #5
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Quote:
Originally Posted by Gach View Post
The HP 9375 is a good carb, the other one..well don't waste your time.
so I've heard....why is that ? the only difference is 100 cfm, it's the same design, 9375 and 9377, identical carbs except they are 1050 and 1150 cfm
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Old 09-17-14, 02:23AM   #6
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Carter would bevel the primary throttle blades to fine tune the timing on the idle transfer slots to suit various engine packages for OEMs.

You can see it on Carter carbs that were on the 389s from the sixties.
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Old 09-17-14, 03:19AM   #7
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Quote:
Originally Posted by Zedo View Post
so I've heard....why is that ? the only difference is 100 cfm, it's the same design, 9375 and 9377, identical carbs except they are 1050 and 1150 cfm
I'm Just saying it's a better carb for your Application. You don't really need a 1150..from reading your description of the one you have. I ran one for years has the four corner idling circuits.
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Old 09-17-14, 08:21AM   #8
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yeh you're right, 1150 cfm is too much carb for this engine. I just had these laying around and wondered if I could get them working and tinker.

a list 4781 Holley 850 cfm double pumper would be better yet. a little more cfm and 4 corner idler

the one on it now is a 780 cfm vac sec and only front idler. being it always had a rich idle with the drilled idle feed restriction and only front idle circuit, I didn't want 4 corner, it would only be richer yet. changing out the front block and fixing the main well emulsion holes fixed that.

the message boards are full of threads with guys trying to tune these 1150 and 1250 cfm 3 circuit Dominators and can't them dialed in, especially on smaller CID, lower HP combinations 400-470 cid. even the ones sent to the carb pros come back f-ked up and sometimes worse than before. when the engine gets over 500 cid then any Dominator seems to work great and pull like a train.

one guy was struggling with a 434" SBC and 1150 and was constantly lean. he could not get enough fuel in the engine at WOT and had high exhaust temps. there was even a few guys who ran 3 circuit carbs who took the jets OUT and still were not too rich. it's because the idle feed ????? are pressed into the main jet passage and partially obstruct it.

the phenom is, if the carb is too big for the motor, it goes lean up top, there's not enough signal to pull the fuel in. the boosters and main system likes to feed a high HP engine.

and it goes rich at idle and midrange, the signal is so strong that it pulls too much fuel in, and the intermediate idle circuit only has one air bleed, the fuel is not emulsified as well as the main circuit feeding the boosters- makes it run like schitt at part throttle.

the 3 circuit Dominators are a kooky setup. they have the idle feed restriction ????? pressed into the main jet channel, right behind the jets. remove the jets and you can see them in there. so the idle system is drawing off the main jets.

the biggest problem is, the o.d. of the ????? themselves partially blocks the main jet channel and leans the main system out at WOT high rpm. these carbs have no power valve or threads to even screw one in, the blocks are cast solid with no power valve holes at all.

end result a Holley with jets, separate idle feed restriction holes, and power valve, can put more fuel in the engine than these Dominators without power valve and idle ????? pressed into jet channel. if used as designed on 2-4 setups the 3 circuit would run better, as there is then 2 carbs to feed the engine, instead of just one.

these 3 circuit Dominators were designed for smaller CID engines, independent runner manifolds, no plenum or small plenums, and 2-4 setups during the early 70's. they were never designed to be used as a single-4 application, that is printed in big print in all the Holley literature. yet they were being bolted on 1-4 race car engines, because these 3 circuit carbs were cheaper to buy new. today very few use an IR manifold. most have a plenum of some sort under the carb(s) on a tunnel ram.

the 3 circuit Dominators are an anachronism.

a·nach·ro·nism

a thing belonging or appropriate to a period other than that in which it exists, especially a thing that is conspicuously old-fashioned.

ex: "everything was as it would have appeared in centuries past apart from one anachronism, a bright yellow construction crane"

•an act of attributing a custom, event, or object to a period to which it does not belong.

Last edited by Zedo : 09-17-14 at 08:46AM.
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Old 09-17-14, 02:10PM   #9
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The problem with the Pontiac's has always been going lean in the middle. So they either to rich for idle or can't get it fat enough. It always shows up on the dyno. So when guys just bolt a carb on they end up going crazy trying to jet it and never get it right.

Ran the 9375 on the 462 motor but when I went to the 505 we just couldn't get it right. 720 hp. But a call to Pro System with dyno sheet, he did a good job explains what was happening, next day had a carb he built, bolted it on made couple more pulls, 761 hp pick up 41 hp. But their was two different tunes one for the street and one for the track. Best learning experience I ever had. That Pro System had 8 air bleeds, and it was just a matter of changing out a couple of air bleed front and back to run it in the street.

Learn my lesson never again mess with carbs with out knowing what the motor is doing and you not going to know that by making runs up and down the street. Not you but you take a hell of a chance washing out the rings and there goes 60 hp out the window and you didn't even know you did it. Before you know it your changing carbs and it gets worse. When you can bolt on a carb and pick up. 40 hp with out messing with trips to the track or other carbs you've saved a ton of money. For me if your not dynoing a motor how do you know exactly what it wants your just playing a guessing game. Just my thoughts.
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Old 09-17-14, 10:38PM   #10
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yeh a good Holley carb man can do wonders. depends on who is building the carb too, some talk a good job, but don't perform.

back in 1990's when Barry Grant was becoming a name as go-to man for carbs, I called him up and told him what we had in a roller cammed 455 w/E-heads. he asked for car weight, gear ratio, compression, cam specs, trans type, head flow, exhaust type, vacuum at idle. I knew all that off top of my head cuz I just built the motor for my friend, so I was able to give him all that info right there first call. the guy who owned the car gone the typical route for a 455- first high CR cast iron head, to low CR cast iron head, then E-heads. just about all of my Pontiac friends went through those stages with their cars, and we'd get the blocks, heads, rotators machined and assemble them at my garage. we always had something in their being built, it was a fun time- and most were Pontiacs. Well BG said all he needed was a 4150 style DP carb, not a Dominator, and he built us a 950 DP based on a 4150 Holley- custom made, with all the top blending, special boosters, bleeds, acc. pumps, etc. the carb was about 2x what a new Holley 4781 cost new back then.

it was worth every penny- when I got the carb and bolted it on, holy crap it was dead nuts on. after bolting on stock Holleys and they always were on the rich side, this one was a dream. I didn't have to jet it or pull the fuel bowls. all I had to do was turn the idle mixture screws about 1/8 turn if that for idle mix. but had I been a dummy and just left the idle mix where it was, it would still have run and worked awesome. it was truly a bolt on and go deal. how he figured that stuff out was amazing. he knew what it needed to be based on the specs over the phone. these guys can see the fuel curve in their mind just by knowing the specs.

lately I'm seeing too much reliance on the dyno, I think it's because most people can't afford to actually race a car all year, or go onward after that for a couple years, like in the old days- or they don't have the time, or don't need the hassle of towing, and all the maintenance work on the car. or their kids need attention or the wife give them schitt about it.
but they can dyno it in one day and brag about their dyno number, and the car just sits in the garage.

that's what the hot rod hobby has become to many in the past 10 years. life goes on. I used to drive my car to work every day in the 1990's. imagine that today, daily driven 455 year round- and a few years had snow tires on it back then for winter.

I personally never had one of my own engines dynoed and will never spend a dime doing it. my mind would not change even if I won the lottery today for $500 million.

the BBC my buddy put in his Chevelle, he had dynoed. after they got done and tweaked an extra 50 HP out of it, over what the crate motor was rated at, he put it in the car. well it had a hesitation problem at part throttle with the dyno tuned jets in the carb.

I had to put the old jets back in and the problem went away.

see, the car has to go down the road smoothly too, if it's a real street car. the dyno can't show drivability problems.

these 3 circuit Dominators are the monkey's paw. the trend now is to convert them to 2 circuit, if running them as a single 4 setup. if you read yellow bullet and a few other boards that show up on a google search of the subject, you'll see the guys with the big CID Fords and Chevys talk about Dominators in general- they idle ok, run good at WOT, but run like schitt and load up and are rich in the midrange. that's why they do away with the 3rd intermediate idle circuit. but the result is a leaner carb with no power valve. so then they install new metering 2 circuit blocks in the carb that accept a power valve, and move the idle feed to it's own orifice, instead not inside the main jet channel.

well hells bells by that time they may as well just BUY a new 2 circuit Dominator, instead of building one from a 3 circuit Dominator. you are 100% correct and right, the time and expense they spend on the carb, they could have just called someone like we did back when, and got a carb on the engine running within 95% of the best it could be.

just reading the threads is tiresome, and I saw a post by another guy who said he read them for hours and no one comes to a real conclusion on a straightforward way to fix the carb. they hunt around the subject but no beef or punchline in the thread.

I actually have 2 of those 9377 3-circuit Dominators. one given to me on a trade as a toss in that was brand new, and another one brand new I borrowed from a friend, and he never asked for it back.

now I know why he never asked for it back....

Last edited by Zedo : 09-17-14 at 10:56PM.
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Old 09-17-14, 11:35PM   #11
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That's why mines pump gas and I can take it out when ever I get urge. runing 9's on pump gas was on my Bucket list, that's check off.
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Old 09-18-14, 05:53AM   #12
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yeh buddy...you don't have to take it out often, even if it's only twice a year, it will never fail to put a smile on your face when you punch it.

a lot easier than towing it back/forth to the track
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Old 09-18-14, 09:18AM   #13
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I found a thread on 9377 Dominator carbs and the big block Ford and Chevy guys are getting them to idle better with air bypass passages in the top. This is basically a vacuum leak drilled into the carb, so the throttle blades can be closed more at idle. PCV valve will do the same thing to some extent. I did this on an 800 cfm Qjet by drilling holes in the side front of the carb into the vacuum chamber that feeds the small vacuum ports on the carb. It works and the Qjet ran great part throttle and out of the hole, but would run out of fuel at about 4500 rpm. I was running it without any metering rods in front or back, just the main jets and metering holes in the carb body. It would suck the bowl dry at high rpm, could not pass enough fuel to feed the heads and ram from the tiny needle valve/seat.

I have a mod for the intermediate circuit on the Dominator, if I can find the right hardware to pull it off. It will require careful drilling in a drill press or Bridgeport, while holding the carb in a vise so it doesn't move, cuz there's not a lot of material there.

check this out, some pretty crafty guys have delved into the 9375 and 9377. I know why, cuz these carbs show up dirt cheap for $200 or less on Ebay often. Bill Jones custom makes a big adjustable air bleed i.e. vacuum leak valve drilled/tapped into the center of the Dominator carb. got a rich idle that is too high ? add vacuum by opening the valve with the turn of a screw.

http://www.network54.com/Forum/85220...or+help+needed


9377 dominator help needed.....
March 21 2004 at 10:32 AM
No score for this post wayne y (no login)
from IP address 199.35.234.59
I have a 9377 dominator (non HP) on a single 4 598cid c-460 headed motor. problem is the car drives terrible around the pits and on the street. plugs always look black when jetted for power ( et and mph ). last year i drilled out the idle air bleeds and it helped the idle. what i was wondering was since this carb was calibrated from holley for a tunnel ram dual 4 setup is that why it is hard to get tuned in? Is it just a matter of getting the air bleeds matched for a single carb application? if so where can i get the air bleed size for an 80556 ? drilling and taping the air bleeds for the 10-32 thread is no problem. I don't want to send this carb out to be reworked because it is not an hp and i can't spend the money on an hp right now because i am deep in a house project right now. thanks for any help.
wayne



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It's all about the exposed transfer slot length
No score for this post March 21 2004, 1:59 PM
-The transfer slots are about 1/4" long and there is supposed to be the absolute minimum amount of those slots showing on the underside of the throttle blades at idle.
-All of the slot that is above the blades acts as an air bleed into that slot and leans the fuel mixture entering the engine.
-When you have the blades up on the slots at idle you give the engine way too much fuel thru the slots and at the same time the rest of the slot above the blades is less so it like a variable adjustment of the engines idle fuel.
--------------------------------------------
-So the idea is to get the idle air into the engine some other way that past the throttle blades.
-Such as using a PVC valve will act as an idle air source or graduating up in size drilling small holes in the throttle blades up to as large as .155" (one in each blade).
-I don't like to drill the blades as that makes the air move past the boosters and causes the boosters to drip or start flowing a little early.
-To fix the problem I drill thru the airfilter stud hole with a .265" drill and then I angle drill another .265" hole to intersect the down hole about an inch down from the top, deburr it all.
-Then I run a reduced shank 5/16" nc tap down past the bottom of the angled hole and I make a long threaded stud or bolt that can be screwed clear down and close off the angled hole.
-This fastener can then be adjusted up or down to allow the angled hole to flow air at idle.
-This allows you to back the throttle blades down on the slot and open this bypass circuit to get the engine the idle air it needs.
----------------
-If you use the center stud to hold a filter or something then that all has to be considered.
-On my carburetors I machine the bottom of the fastener I mentioned so that it can be rotated 1/2 a turn and fully open the angled hole or 1/2 turn will fully close it off.


Another thing that will help dominator street driveability...
No score for this post March 22 2004, 7:37 AM
Hey Wayne, something else that will help the street driveability on the dominator is to install "progressive" linkage. If that carb was made for a tunnel ram it probable has "soft progressive" or 1 to 1 linkage. That means the primaries and secondaries are almost always opening at about the same rate. That means when your driving around at low speeds all 4 barrels are partially open in the transition phase.

I like the progressive linkage alot better because it allows you to drive around on the primaries only 90% of the time when you're cruising.

The other thing on a 3 circuit dominator is what you have already dealt with a little bit. The idle and transition air bleeds. These are calibrated WAY too rich for a street engine. You've already messed with the idle bleeds but you can go way up on the transition bleeds. Mine are currently about 15 numbers bigger than the ones that came in it from the factory.



Re: 9377 dominator help needed.....
No score for this post March 21 2004, 11:20 AM
I have used the 9375 and 9377 2 carb calibration units as a 1 carb with good results . I actually preferr them in that they do not have power valves . If the idle is rich I open the idle air bleeds .002/003" at a time untill the engine is happy with the mixture screws not less than 1 turn out . Be careful not to get the engine too "happy" at idle . It will cause the engine to idle up as heat builds and could cause a stumble . Like you said , putting the 10-32 screws in the old style carb is no big deal .
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Old 09-26-15, 07:01PM   #14
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the weather cooled off so I have a bunch of carbs out, cuz I'm always trying to improve them. I got a 780 cfm with downleg boosters, an 850 double pumper list 4781, and the Dominators. researched it more in the Holley manual, and then called Quick Fuel in Kentucky. between the 2 found out what's happening with the 3 circuit Dominators.

what I found out after careful reading, net research, and asking very direct, specific questions to the Quick Fuel tech man, is this:

using 2-4 bbl carbs splits the available vacuum signal in half, and makes the carbs run leaner. less draw on the idle and main circuits, cuz it's pulling through 8 barrels, instead of only 4.

Holley developed the 3-circuit Dominator around 1970. they copied what was at the time, the Mopar 383-440 emission metering blocks, which were 3 circuit. keep that in mind, because that's why these carbs are so lean at WOT. often the timeslips don't improve with jet changes, or even when the jets are removed completely, if a 3-circuit 1150 is put on a single 4 barrel intake. yet it will be pig rich at idle and midrange.

these 3 circuit blocks have the idle feed restriction tube, pressed into the main wells, if you remove the main jets, you can see the bottoms of the ????? inside behind the jets.

this carb design was originally released in Dominator form, as the list 6214 and 6464 carbs. if you find an old copy of the Holley carbs manual copyright 1976, they are both covered there.

now the critical point- both carbs were designed NEVER to be used in a single 4 barrel application. they were designed as a dual-4 barrel only application, where the available vacuum signal would be split in half between 2 carbs, and 8 barrels.

with less available signal on a 2-4bbl setup, they were calibrated very rich at idle/part throttle, and a 3rd intermediate circuit added, to provide enough fuel to cover the weaker signal using 2 carbs.

the 6214 was designed to be used on an IR independent runner manifold, 2-4 setup, and 1150 cfm per carb, and specifically designed to dampen fuel "standoff", a cloud of fuel mist that forms above the carbs on an IR setup. It was used on Ford small block 302, with one barrel per cylinder, no plenum. also with a plenum later, where the carbs had to be jetted up the larger the plenum size.

the 6464 was designed to be used on larger engines with a tunnel ram, 2-4's, and plenum and was 1050 cfm each carb.

again, NEITHER carb was ever designed to be used in a single 4 bbl. application, and the Holley manual specifically states that many times.

fast forward, the later 9375 and 9377, 1050 and 1150 Dominator carbs, are direct descendants of the 6214 and 6464, with all the related foibles of being 3-circuit carbs.

I ran a 3 circuit 1150, 9377. I was given 2 of them for free, from 2 separate people. the problem with them is this- if you try to run them on the street or bracket car with 1-4 bbl, the idle and part throttle is pig rich. the top end is lean.

reason being the idle transfer slot is very long, and intermediate comes in and makes it even richer- so idle/part throttle is pig rich. then at WOT, the idle feed restriction ????? in the main jet wells, restricts WOT flow, and leans WOT out.

these carbs can be lean at WOT even with the jets removed. and jetting down to try to clean up the idle/midrange, makes the WOT even leaner yet. the much stronger signal of any engine with only ONE CARB, throws the calibration of these dedicated 2-4 tunnel ram carbs, out the window. there's just too much signal at idle/part throttle and it's always rich. with only one carb, it's always going to be lean at WOT too.

the fix is, open up the idle air bleeds, and intermediate air bleeds, a dramatic amount. and replace and reduce the diameter of the main air bleeds. not hard to do, but time consuming.

or, change the metering blocks to conventional Holley 2 circuit, and do away with the intermediate circuit altogether.

a few have gotten decent street drive-ability by just plugging the intermediate circuit, and running it on the idle and main circuits only.

these carbs have no power valves, the pv is factory blocked with casting, and there are no pv channel restrictions drilled in the blocks. the intermediate system feeds by a pair of .038" drilled restrictions in the front of each metering block.

Holley made metering block kits 85r-5230, that took a power valve, and put more fuel into the engine at WOT, but stated it still put less fuel in the engine than a dedicated 1-4 Dominator.

so there you have it.

having said that, there's a lot of these carbs around, and if you want to tinker, you can pick up a 9375/9377 Dominator on the cheap, and convert it, and have a low buck racing carb.

it needs the metering blocks, and air bleeds dialed in, per application, for a single 4 app.
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Old 10-25-15, 03:24PM   #15
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Quote:
Originally Posted by Zedo View Post
I have an old Holley 9377 given to me free 20 years ago. the carb was bought new around 1990. it gave the owner fits and flooded constantly and fouled the plugs all the time.

this is the one that had the warped main body metering block surfaces from the factory, I had to machine/file flat to get it to stop leaking gas into the primaries. Holley had a QC problem where the new gaskets would "pillow" these warped main bodies and they'd run for a week or two when new ok, then as the gasket got compressed would start leaking.

this carb has no power valve provision, the PV threaded hole is completely absent. what is has is a 3rd circuit called the intermediate idle circuit, with an extra drilled hole to feed just that passage with fuel. this is above the curb idle discharge hole and off idle slot in the bores of the carb. there are 4 of these intermediate idle discharge ?????, one for each barrel

these carbs were originally designed for 2-4 applications or for an IR independent runner intake, they were never designed for single 4 application.

I'd like to convert the carb to the old style conventional 2 circuit Holley metering block design. this eliminates the intermediate idle discharge ????? altogether, so all the metering on power and WOT is done only by the main system boosters. (the big rings up top in the middle of the bores)

has anyone done it ? I hear varying approaches i.e. change the metering blocks to standard ones from a 4150. or, use a gasket that blocks the intermediate idle port while using the same blocks it came with. or, put lead split shot fishing sinkers in the discharge port ????? to just block them. (that last idea actually came right from Holley tech service)

looking at the carb, what is really needed there is another idle mix screw to adjust that intermediate idle fuel port. that would mean drilling/tapping and risking ruining the carb though.

what say you ?
We do 2-circuit conversions & upgrades here on a regular basis.
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