. It has a Holley HP main body, 650 DP metering blocks (4777-2) fuel bowls and throttle body. Recheck the front idle after the rear setting has been confirmed. This reading is taken at the manifold vacuum port at the base of the carb front. The hole in the base of the throttle body leads up to the vacuum port at the top of the carburetor. It was a 302 (10:1) with a Holley 600cfm vac secondary; Malloy unilite vac, comp cam 268H, dual plane manifold, full length hooker headers with dual 2.25" exhaust attached to a 4sp top loader with 3.55. adjusting 4 corner idle on #4779-9 holley 750dp. Repeat with the back bowl if you have a 4 barrel carb. Had to use the spacer to clear the vacuum port on the manifold to the brake booster. Due to supplier delays, orders may take longer to arrive. 1300 rpm's! For starters lower the fuel pressure to about 6 psi. This is my final tune on a Holley 750 with a Proform main body, and the engine runs flawless at any RPM, load, and throttle position. Timing is 15 initial, 35 total. A big-cam engine needs a higher idle speed, which is usually about 1,000 rpm; a regular street cam needs about 600 rpm. It seems that the best fairly steady vacuum that I can acheive is -5hg with the idle mix screws set at about 1.5 turns out. The idle draws air and fuel out of the transition circuit. Search: Holley Carb Idle Adjustment. Any more and mixture gets rich, while loosing vacuum. You could almost stall the car with it if you held your foot there. If you have to, make a hole in the gasket. In operation, the accelerator pump is connected by a linkage to the throttle butterfly shaft. Drop Ship; Only show this user. NOTE: the kit contained a power valve of lower in hg rating (1.5) vs the presumed factory one (5.0) so I went with the new one in case the old one might have been bad. I tune a lot of Folk's carbs at different car events, and this one methodology in initial adjustments cleans up almost everybody's issues right from the get . Feels like a "flat spot" from a carb with a too small an accelerator pump. Only difference would be H.P. I'm running dual holley 94's. I got it tuned in pretty well but it seems to have a flat spot off idle. my problem: off idle bog. Holley 4160 Carburetor Kit "It looks the same HOLLEY 600 CFM & EDELBROCK 2701 manifold package suit sbc chev 350 327 400 carby - $885 Edelbrock 1905 Avs2 Manual Choke 650 Cfm Square Bore W Free Black Air Cleaner Edelbrock, LLC is an American corporation engaged in the design, development and manufacture of specialty automotive and motorcycle . Unfortunately, my engine only requires light throttle to keep the car up to speed, so it can get annoying. Any more and mixture gets rich, while loosing vacuum. The engine is a custom made 383 stroker, by a well known builder. It was a 302 (10:1) with a Holley 600cfm vac secondary; Malloy unilite vac, comp cam 268H, dual plane manifold, full length hooker headers with dual 2.25" exhaust attached to a 4sp top loader with 3.55. RJP66F100. This is used for the distributor advance and needs to be open all the way to the intake vacuum. Here are the steps for calibrating the idle mixture: Progressively turn the idle-mixture screws in. Jun 2, 2009. It ran like a champ, smooth as butter and could regularly smoke mild 350 built equipped Chevys. Cold Holleys, try 3 good pumps ( not smashing your foot into the floorboards) to introduce some fuel into the manifold. Replace the sight plug in the side of the fuel bowl. That's why they have accelerator pumps. It ran like a champ, smooth as butter and could regularly smoke mild 350 built equipped Chevys. Engine setup: 250c.i. inline, 5000 miles on rebuild, stock other than 0.030 over, 390 cfm Holley on Offy intake, Mallory #4563801 dist. He has a new holley 4160 750 cfm DP carb. Arnold Ca. It's on a GMPP ZZ502, M21, 3:07 rear. It was better after I put both accelerator pumps down on #1 from #2. the Proper method to set your idle speed on your holley carb. I have set all of the floats correctly and adjusted the idle mixture screws using a vacuum gauge. Holley 600 cfm carburetor 66 jetmain 72 secondary 6.5 pv. The engine is a custom made 383 stroker, by a well known builder. I have installed the Pro Flo 3 on my '66 Chevelle. Final Day! While there are other issues that may cause similar reactions within the carburetor, often the problem can be traced back to the accelerator pump system. The engine idles at 14.0 when warm, and cruises at the leanest possible AFR of 14.0 without any lean misfiring. jets: 66 fronts, 72 rears, Power valve: stock (6.5) Accelerator Discharge Nozzle: Stock (.025). This makes them require excess choking (which wouldn't be so bad if the fast idle ramp was curved better). as long as you increase RPM slowly, it revs up just fine, in fact i'd say it runs good. at idle and 9.0" Hg. Learn more. choke, and vacuum secondaries. Carb Part Holley Lean Throttle At. Part Number: HLY-142-29. Current jetting is what Holley gives as a baseline for the HP main body upgrade, which is 72/84. Started right up but the idle is way too high. Reduce the idle speed and repeat the process, perhaps several times, until the engine idles at the desired engine speed. Idle cranking will not create enough vacuum draw to start the idle circuit. a question with already asked and answered on blank page. Tuning Holley Vacuum Secondaries. So it's almost like 2 carburetors, clearly focusing on performance more than economy. Didn't help. in drive. The accelerator pump circuit (s) in a Holley carburetor acts to smooth the transition between the idle circuit and the main circuit. Attach the throttle plate to the shaft with the screws so that the numbers on the throttle plate face the idle mixture screw and the dimples face in You may have to flip the carb over to see it So it may be easier to just swamp to 2280 This in turn leads to a lean, flat spot just for the briefest moment 2 . adjusting 4 corner idle on #4779-9 holley 750dp. My problem is that at a normal idle there is a flat spot on takeoff from a stop and the bike even stalls sometimes if I dont hit it just right. The carburetor is a wondrous but sometimes-mysterious device mounted on top of an engine that makes it run. Have a beer, you have just taken care of the #1 problem with most Holley carbs. This too arrived with a few problems and I sent it back. The car has a terrible stumble off of idle. One of the first things I noticed about this 850 Street HP was the accel pump squirter was 28 front,29 rear. Filters. Off-idle flat spot/bog is one symptom of insufficient fuel to support the amount of air you're letting in with the throttle. this is very important and once they are set they must be left alone. Not Yet Reviewed. however, when you try to increase engine speed too fast, it bogs, or stumbles before . Incorrect adjustment is the typical culprit. Hesitation, backfire and lean conditions can also be the result of an improperly adjusted acceleration pump assembly, and should be checked using these procedures. Flat top forged pistons 6" forged rods Comp Cams Extreme Energy advertised duration 294/300 2 - Holley 4160 450 CFM carbs. then check over the accelerator pump, with the car shut off, work the throttle slow and watch the nozzles, make sure there are no dead spots in the entire pump range from dead off idle to wide open. My Current Car Setup: Compression - 9.3, aluminum heads 64 cc combustion chambers and 190cc intake runners, 218-224 @ .050 on 110 LC cam, long tube headers, 2 1/2in exhaust, 3.50 gears, tko 500 with a holley 770 street avenger. Jet extensions and notched float in the rears. Went from #6.5 (stock) to #4.5 on power valve as I'm only getting about 16" Hg. it starts and idles with no issue. I run a MSD AL2. It happens at pretty much any speed, but only at really light throttle. Engine setup: 250c.i. I've got a bad flat spot off idle and it's driving me to drink. I run a MSD AL2. Installed with a gasket, phenolic spacer, gasket. Sure enough, had a stumble or flat spot with "new" carb installed. The engine runs great with no flat spots, good off idle transition, WOT ratio around 13:1, cruise ratio of around 14.5:1, and idle ratio also around 14:1. Out of the box, it was equipped with 74/84 main jets which I changed to 72/82. The first result of a long-duration camshaft with lots of overlap is drastically reduced idle vacuum. Smaller than my 31 front,35 rear on my old Holley 4781-2 I was removing, but I would give it a try before changing any parts. they need to be set at .020 or simply as small squares like you can see in my picture. 11-13-2018, 01:10 PM. I have a wicked flat spot off idle (It has stalled) and a stumble off decel at about 20 mpg. Start with a quarter turn on each one and readjust the idle speed to an appropriate RPM. Quicksilver II carb flat spot off idle. Smaller than my 31 front,35 rear on my old Holley 4781-2 I was removing, but I would give it a try before changing any parts. Hei ignition 12 to 14 degrees initial timing with 32 to 34 total. Close. Or it you let it sit at the flat spot for a second or two it'll pick up and take off like normal. One of the first things I noticed about this 850 Street HP was the accel pump squirter was 28 front,29 rear. RJP66F100. the holley is a 770 street avenger, electric choke, with vacuum secondaries. I have pretty much ruled out the carb since I have been working with Holley (for about 3 weeks) and finally replaced it with . I have a QF 750 double pumper drag race carb installed on my 327. Carter AFB Flat Spot off idle, cold engine Theme . Aug 4, 2006. Give it a little more gas and it doesn't go any faster, give it some more and it'll pick up. Regulating the airflow into the carburetor are throttle blades that are . 2. Hey guys its been a while but I am having some issues here. What else I noticed was when the engine is in the flat area the engine sounds like it goes lean and misses slightly. A Holley is a vac drawn system. These correction factors relate directly to writing track and jetting. with mech. I've got a bad flat spot off idle and it's driving me to drink. Edelbrock RPM Air-gap intake. and fuel efficiency. Holley 4150 double Pumper - kind of a cobbled together carb. Vacuum advance is 14 degrees added when cruising total of 46. Redline Your Savings . The way it works is by drawing fuel and air into the engine by way of a vacuum that is created while the engine is running. Pierce-Arrow Template . Carburetor Jets, Emulsion, Holley Number 292, Hole Size .0292 in., Pair. Find Holley Carburetor Idle Feed Restrictors and get Free Shipping on Orders Over $99 at Summit Racing! It idles nice and once it picks up the rpms it pulls nice too, but it takes a second for it to get going when it almost wants to die. Timing is spot on, compression is 170-175 on all 6 cylinders, and I rebuilt/cleaned the carburetor using OEM repair kit 3854341. I've got a '77 OMC 235 HP (Ford 351) with an Edlebrock 1409 carb that is stumbling just off of idle. Some dominators are an exception and have separate air bleeds and feed restrictions for each. The carb I am using is a NOS Holley 9834-1 Here is what happens: Car starts fine hot or cold. The "Bog" simply means the engine is not receiving enough fuel when you go to wide open throttle. Gm zz4 208/221 roller cam. The answer is amazingly simple. The missing spring from the dashpot is not the problem. When you have the correct adjustment, hold the NUT in place while you tighten the SCREW down. The carbs have your questions. Off-idle stumble. with mech. These bikes have slightly different carb jetting, but they are all rather lean on the idle circuit. This assembly delivers an initial shot of fuel in the right amount, and duration, to provide crisp throttle response right off idle. The only way to obtain the highest vacuum, and get my 383 stroker to run its best, is to have all four idle mixture screws turned out a half of a turn. Holley 750 DP (4 corner idle), with Proform main body. The only way to obtain the highest vacuum, and get my 383 stroker to run its best, is to have all four idle mixture screws turned out a half of a turn. I am helping a friend troubleshoot his 383 stroker and we are tearing our hair out. Loc. The flat spot disappears if I set the idle too high, but then I sound really stupid sitting at a light with the engine almost . My 408 with a 750 Dp holley has a flat spot at 1200-1500 rpm. I've got a bad flat spot off idle and it's driving me to drink. Default old (Default) Copy of Default . Posted by 6 years ago. advance only. world sportsman 2's bowl blended and ported. Instead of 16 to 18 inches of manifold vacuum at idle, many big cams will support barely 4 to 6 inches. Would the flat spot off idle be caused by running too big of a jet? Have change squirters from #25 (stock) to #28 then to #31 as Holley says that undersize squirters are the most common problem. $10 Off Your Mobile App Purchase - Get the App Final Day! if no dead spots are found then you may need to step to a different pump . I've followed the tuning procedures listed in the carb manual and just can't get this stumble cleared up, it happens ~ 900-1,200 RPM and runs fine everywhere else. I've tried every combo of .098 and .101 primary jet with metering rods 1447, 1444 . Engine run down. WOT is 12.5. But both would work with no bog, no spit no sputter, no issues. 785. gold coast , australia. Estimated Ship Date: Jul 25, 2022 if ordered today. Having this covered up will cause problems. Hooked up all of the vacuum hoses and new fuel lines. If your aftermarket Holley is equipped with four-corner idle circuits such as the 4781 shown in the photo, set the front first, then set the rear. Turn the idle speed setting screw to set the bottom edge of the advance only. Electric choke works great, after the choke comes off and the car idles at 800 rpm glass smooth. Sure enough, had a stumble or flat spot with "new" carb installed. On holley carb! As well via a channel with a flat and blocks. You can bandaid the slight overcarb condition by playing with the accelerator pump adjustments to get rid of the off idle flat spot caused by poor vac signal. Aug 26, 2010. One method of setting up your idle system is a follows: To start with, invert the carburetor and check the position of the throttle butterflies. We used it on a 4779 Holley used on a 331" road racing motor and it worked very well. Have change squirters from #25 (stock) to #28 then to #31 as Holley says that undersize squirters are the most common . having some minor issues trying to get a slight off-idle bog possible lean tip in ,i've got the a/f screws right now about 3/4 out but it did idle better at 1 turn out originally but slight rich sensation "eyes watering" but not very bad but noticeable . This reduced vacuum requires more throttle opening to feed sufficient air to the engine since. March 23, 2014, 12:05 AM. bigblock665 the absolute first thing you have to do with a holley is turn it upside down and set your transition slots. Most Holley carbs do not have a separate idle and transition circuit, the both share the same fuel and air which are the idle air bleed and the idle feed restrictor. Anyway, since I had done this 041-inch high-speed air bleeds It has annular primary boosters and 4 corner idle adjustment Screw, Plump Lever Adjusting 24 L0127: BOOK - Holley Carburetors, Manifolds & Fuel Injection revised 4th Edition, a detailed guide to Holley carburetors and manifolds, this book covered high-performance carburetors, selection and . When properly adjusted, there will be no hesitation or stumble when the throttle is opened. Have change squirters from #25 (stock) to #28 then to #31 as Holley says that undersize squirters are the most common . If so I'll try a 66 jet, or even a 65 and see if that makes a difference. Instead of 16 to 18 inches of manifold vacuum at idle, many . Find Holley Carburetors 750 CFM and get Free Shipping on Orders Over $99 at Summit Racing! I replaced my carb today with a new Holley 670 street avenger, elec. . inline, 5000 miles on rebuild, stock other than 0.030 over, 390 cfm Holley on Offy intake, Mallory #4563801 dist. There are exceptions, for instance the Holley double pumper has its own idle circuit and accelerator pump, and are directly linked to the accelerator linkage, though delayed. I can get 20" hg at idle, steady gauge with no fluctuation. Timing is 15 initial, 35 total. Pump cams are orange in the #1 position. #1. Done Open the throttle slightly and it all goes away. The other scrutiny of vacuum connection on a Holley is ported vacuum, which also weak off idle, mode at cruise, and apply at . ! Clean up the spilled gasoline. Eventually I sent it off to the rebuilder National Carburetor, which had done a flawless rebuild on a big Holley 4-barrel for my '77 Mercury. There is a theory that I proved wrong many years ago, that says to use smaller jets and a bigger power valve. In addition to the ignition quirks, he addressed another common problem with these bikes: the "off-idle" flat spot on '75-'77 models. I have a stock 302 with an edlbrock manifold, Holley truck avenger, pertronics ignition. $10 Off Your Mobile App Purchase . My choice for starterswould be in the area where early and late Ford specs meet: CG-Ford-Holley AA-1 Float/Fuel Level Information: Levels from 1939 Holley Service Sheet Form . I have tinkered with the carb just a bit by increasing the primary jets to 72's and the secondaries to 70's. I pull it apart for a good cleaning every spring, and the . Problem has been from day one: Hesitation off idle, pop through carb, surges up and down until rolling. March 23, 2014, 12:05 AM. having some minor issues trying to get a slight off-idle bog possible lean tip in ,i've got the a/f screws right now about 3/4 out but it did idle better at 1 turn out originally but slight rich sensation "eyes watering" but not very bad but noticeable . It actually hesitates slightly similar to a bad accelerator pump at 1200 rpm but the pump looks fine. If you bought a new 650 or 700 BG Race Demon double pumper, the difference between that and a standard Holley carb is very noticeable. I collected float specs from many US and foreign sources on these things, and here's a list of the numbers I found for Ford 94 AA1 family of carbs from the flathead years. 350 sbc. Obviously, the 300 cfm carb would not let the engine make power to 6,000 rpm, and the 850 cfm carb would not get the same low speed throttle response as the smaller carb. Jets The jets are the main holes that the fuel has to pass through. 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The problem had a stumble off of idle after the choke comes off and the car idles the. Delays, orders may take longer to arrive 292, Hole Size.0292 in. Pair. Have just taken care of the transition circuit to about 6 psi the intake vacuum operation the! These correction factors relate directly to writing track and jetting of.098 and primary... A 770 street avenger, elec a long-duration camshaft with lots of overlap is drastically reduced vacuum! Off Roading Forums < /a > Off-idle stumble off idle from a carb with a gasket, phenolic,... Slightly and it & # x27 ; ve tried every combo of.098 and.101 primary jet metering...