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holley carb

 
dale49 dale49
I love my Chevy Chevette! | Posts: 16 | Joined: 07/13
Posted: 12/08/13
01:09 PM

i bought a trk the previous owner converted it from tbi to aluminum intake , spacer and a non chocked holley 8105B carburetor, its running rich, way rich, can somebody tell me how many cfm this thing is, i would like to know before i spend to much time messing with it ( i believe the power valve is bad) im not a big fan of holleys, i think it is just way to big for the trk, it appears to be a stock 350  

wayne712222 wayne712222
V-6 Camaros rule! | Posts: 60 | Joined: 11/13
Posted: 12/08/13
10:01 PM

to find out if the power valve is blown..

turn the idle mixture screws on the sides of the metering block in..  

if the engine dies.. then the power valve is not blown..

if there is too much fuel pressure.. it will overpower the needle and seat.. use a mirror and a bright flash light to look down the throttle bores at idle.. you should NOT see any fuel trickling out of boosters ... all the fuel at idle .. should be coming thru the idle feed ports below the closed throttle blades.. with just a tiny amount of idle transition slot exposed..

oh.. you said chokeless.. does that mean no choke horn.. or just missing the choke blade and shaft..

the LIST number is stamped on the front of the air horn..

Holleyhpcarbleftfront Zpsb361269f

Holleyhpcarbsidemainbody Zps11c39375

Holleyhprightfrontview Zps8103f1a0


hint.. take a video.. post it to youtube or photobucket so we can see how it runs.. this can really help. give us a short tour of the engine compartment so we can see if there are any errors in the conversion..  

dale49 dale49
I love my Chevy Chevette! | Posts: 16 | Joined: 07/13
Posted: 12/09/13
09:41 AM

no choke horn, already did the idle screw thing, took out power valve, sprayed it with carb cleaner, twisted it back and forth a smidge, put it together, and it ran better for a few minutes and then started riching up again, im going to get a power valve today ( 8 bucks), my biggest concern was how many cfm it is, its a chevy 3500 with a utility body, i dont think, high performance tuning is going make it go much faster  Confused  

wayne712222 wayne712222
V-6 Camaros rule! | Posts: 60 | Joined: 11/13
Posted: 12/09/13
07:37 PM

hmm...


QUESTION How do I find the "list" number on my carburetor?

ANSWER The list number for most performance and factory 2 and 4 barrel carburetors will be found stamped into the upper right hand corner of the airhorn or sometimes called the choke tower.

On the 4150 HP models that do not have a choke tower the list number will be stamped into the mainbody behind the throttle linkage. This number is used to identify the carburetor and also used when needing service parts or renew kits.


but they make a whole bunch of different versions..

i have not had one of these in my hands.. i have been drooling over them as they are very adjustable..

i am taking that it looks like this one..

HP Intozoom  

dale49 dale49
I love my Chevy Chevette! | Posts: 16 | Joined: 07/13
Posted: 12/10/13
07:11 PM

here r pics of carb    http://s1273.photobucket.com/user/saltlife49/media/IMAG0306_zps65149c69.jpg.html?filters[user]=134582003&filters[recent]=1&sort=1&o=1  

wayne712222 wayne712222
V-6 Camaros rule! | Posts: 60 | Joined: 11/13
Posted: 12/10/13
08:02 PM

are there any numbers STAMPED in.. to the bottom of the base plate.????

marked with a number punch.. not cast into the part??? applied after the part was produced..


IMAG0301 Zps7db54638

IMAG0300 Zps76d678b9

IMAG0304 Zps39d8dd55  

wayne712222 wayne712222
V-6 Camaros rule! | Posts: 60 | Joined: 11/13
Posted: 12/10/13
08:38 PM

before putting the carb back together.. read this completely.. it may and probably will have several sections..


how about flipping the carb over.. since there is no choke or fast idle cam..

lets see how far closed the throttle blades are...

Idle Transition Slots Setting Zps7bcc767a

if you can adjust the primaries to just barely expose the idle transition slot.. you can just the idle mixture screws to totally control idle mixture..

in you look at the image below.. you have the carb flowing fuel only thru the round idle passages below the throttle plates as designed..

Holley 4150 At Idle Zpsdf8a4c9d




now... look at the throttle plate angle on the image below.. see its part way open and starting to expose the idle transition slot.. so fuel is still being fed to keep the air fuel ratio within the proper range for the engine speed..


Holley Off Idle Zps85779e58



now... when you pull the primary metering block off to change the power valve..

do you see idle feed restrictions in this area.???

Meteringblockidlefeedrestrictions Zps2404a394

these control the amount of fuel that the idle circuit can pull during transition to the main circuit.. but it also controls how much fuel is delivered.. at a low to medium speed cruising RPM..  say 800 to 2200 rpms.. depending on the size of the car.. the idle transition circuit is delivering fuel thru the idle transition slot along with the fuel being pulled up and over by the air flow thru the venturies.

so if your idle feed restrictions are too big.. it will be rich off idle and rich during low speed cruise.. and you will get horrible fuel economy...

if your primary idle speed is set too high.. you will be pulling fuel thru the idle transition slots and your idle will be too rich..

now... if the idle feed restriction is too small... what will happen is it will go lean of idle.. have a flat spot.. might even misfire or break up.. the car will not be a joy to drive. . edelbrock carbs were getting a bad name a few years back.. but they have gotten on the idle transition restriction issues..  after i called them on it.


lets look at some other images...


Idlecircuitdiagram Zpsd255d76d

in the image below..

there actually should be a 4th version between the second and third.. where the idle transition is flowing and the mains are flowing.. that would be low cruise.

Idletransitiondiagram Zpsb9fc2fb9

you can test the idle transition feed.. buy taking the engine to about 2800 to 3000 rpm.. and slowly dropping the engine speed..    if its close or perfect.. you should be able to drop the engine speed to any RPM and have it be stable..  and be able to slowly increase the engine speed without any flat spots or the need to move the throttle lever fast to stop it from stalling ..

some performance holleys also have an additional trick... some have an idle speed adjustment down under the air cleaner stud hole..

you can actually see it in the first or second image above..  its a screw assembly mounted to the base plate that sticks up into the middle of the carb.

since you mention that you are not used to holleys..

all carbs operate on the same circuits..  except variable venturi carbs..

look at the motorcraft autolight and actually holley 4010/4011 and summit idle circuits..

[img[http://i1207.photobucket.com/albums/bb476/waynep712/waynep712%20carb%20album/2100idle_zps0085c49b.jpg[/img]

the edelbrock has the idle feed restriction hidden behind the idle air bleed..

35D5824f C301 4A1e 9D64 0Dbfe2c6dd71 Zps98f001e9

the quadra jet had is also..

Quadrajet Idlecircuit Zpsab2c1514

AFB AVS Booster Assemblies Zpsc75bdda8


the AFB..

Thermoquad Primary Circuits Zps71f03a4d

and this will blow you up.. even the upflow carbs...

Updraftcarb Zpsb298fb77  

wayne712222 wayne712222
V-6 Camaros rule! | Posts: 60 | Joined: 11/13
Posted: 12/10/13
08:57 PM

oh.. and how to you get your idle speed.. if the engine is large..

usually one can open the secondary throttle plates slightly.. this makes a huge difference..  there is a stop screw on most holley 4 barrels..

you might need to test the PCV calibration.. with the engine idling.. pinch off the pcv hose.. the engine needs to drop between 50 and 70 RPMs..if the PCV calibration size is correct.. if the RPMS drop more than 70 by too much.. you may end up with a motor that burns oil at 300 to 400 miles per quart..

on another magazine forum here. we have been talking about using needle valves to create vacuum leaks we can adjust on tunnel ram or dual quad installations..  so we can back off the primary throttle plate adjustments as far a possible to keep from fouling the spark plugs at idle..  

dale49 dale49
I love my Chevy Chevette! | Posts: 16 | Joined: 07/13
Posted: 12/11/13
07:17 PM

there r 2 numbers stamped in the bottom 11064 and 3857  

wayne712222 wayne712222
V-6 Camaros rule! | Posts: 60 | Joined: 11/13
Posted: 12/11/13
07:28 PM

see since you might still have it off.. if you can measure the venturi diameter and the throttle bores at the bottom of the base plate..  

dond1965 dond1965
V-6 Camaros rule! | Posts: 33 | Joined: 12/13
Posted: 12/12/13
09:49 PM

wayne... you kick but dude!  

dale49 dale49
I love my Chevy Chevette! | Posts: 16 | Joined: 07/13
Posted: 12/13/13
04:54 PM

they are approximately 39 millimeter, my digital caliper is dead,
if somebody has a use for this thing i would love to trade it for a 500 to 600 cfm model with a choke