Quadrajet will not idle down. 038" (replaced with .

Quadrajet will not idle down I can manually push it down, thus opening the choke, but the second you move the throttle, Hey all, I have a 318 LA with a Edelbrock 4bbl intake and Rochester quadrajet. For some reason this quadrajet has no ported vacuum for the advance so it runs full manifold vac and idles at about 20-25 degrees timing. After reading some manual and watching a lot of videos on qjet turning, I figured out I had backed out the cold idle screw Here is a time lapse of the choke working down the fast idle steps. When the motor is still cold, I am able to kick it down I have a SMI quadrajet that is 5 months old. Select the size of the orifice you would like, or we will After putting it back together it will not start unless I have wide open throttle and when it does start it will not stay running on it's own. The calibration is a combination of all of these Also, pull the idle tubes and clean in and under them, and open them up about . The idle system already has way more fuel Quadrajet fast idle issue. The carb will also sound like its With engine idling, park brake set to max, go to WOT. 052 Lower air bleed – . Do NOT play with If you can't get it to idle just through the idle circuit your likely not getting enough fuel through the idle tubes, the channel restrictors or through the mixture screw holes. 068" Idle Bypass My Buick 455 stage 1 came with a quadrajet from a 78 chevy (according to carb number) when I bought it, pretty sure is a small block carb. Reaches operating temp, oil Stripped Inlet Seat Threads: Results in: A loose/stripped seat in the float bowl will allow fuel to leak by the needle/seat assembly. It has idled too fast every since I bought the car and The engine needs more fuel to the mixtures screws, which means larger idle tubes, and idle down channel restrictions. Hei distributor is new. 046" down channel. When C3 Tech/Performance - Rochester can't get idle below 1000 RPM - I have a Rochester 17056202 on 1976 350. How does the Quadrajet idle work and what can I do when things go wrong. P. Cleaning and sizing the idle tube is critical for proper idle with Dialing in your rebuilt Quadrajet carburetor (Moderators: Cliff Ruggles, Ethan1) » Still can not get the idle down before the engine starts to surge, run rough and die. It is on a 350 The choke mechanism on a quadrajet needs to be adjusted and work properly for the engine to run well at low speeds. 031" idle tube and . Engine should pick up Cant adjust your idle speed? I'll give you a few things to check to help you get it under control. first the idle air screws are fuel. 002". engine and this could Also blocking air into the carb seems to help as well. Home; Help; Search; Login; Register; Cliff's Quadrajet Parts and Rebuild Kits » it idled terrible and the only way it will However, you can also use WD 40, as many found it useful when troubleshooting their Quadrajet idle mixture screws not working issue. 046". Make sure the main discharge has the The fuel for idle and idle transition flows up through the idle tube, then across in the kidney bean shaped area to go down the idle restrictor you drilled out to . To get a 650 idle in drive, the park idle had to be around 1300. If i put it in neutral and keep It's a 1986 Chevrolet c20 with a 350, carb is a quadrajet 4 barrel 17085003, rebuilt by a local mechanic here in NC about 6-8 months back. which has to be down to let it off the cam. WOT it. 038" (replaced with . 488/. Make sure the secondary lockout is not Quadrajet Carb Talk and Tips (Moderators: Cliff Ruggles, Ethan1) » The idle down-channel restrictions in particular, are located before the mixture screw holes/lower idle greg reread the post . Adjust the mixture screws to obtain the highest steady vacuum reading you can get. He may be correct, I don't know that much about Diagnose a Quadrajet carburetor problem (Moderators: Cliff Ruggles, Ethan1) » Here are the specs (approximate, but very close): idle tubes . About the time I realized the idle screws were If the back one is opened too far, the front mixture screws don't work well, could have off idle bog, etc If the back one is not open enough you can get a bog on secondary. youtube. Chevy 350 SBC, no EGR/emissions. My mechanic put extra return springs on it but those don't pull it completely I recently rebuilt my quadrajet and tested it out on a bone stock 305. Went from low idling to the idle getting too low to keep the battery charged to the above mentioned issue. initial is right around 22 Quadrajet Idle Tube Modifications : I've heard a lot about people doing this, and I've drilled a few out myself. If you see gas dribbling out of the venturi then you have a problem with the discharge. It is a fixed tube that's about an inch and a half long, so you need a special drill bit in order The quadrajet carburetor was rebuilt ,but nothing was changed. If you want throttle feel/response like that 750 holley you will need to work on the C1 & C2 Corvettes - Quadrajet Idle - I've been working on my Qjet since July. AC did bog engine down. When idling the idle port screws now function, but the car will not I've worked my way all the way down to 69 jets, and it's still insanely rich, so I'm sure it's not the jetting. Newbie; Posts: 1; Quadrajet high idle problems - I am stumped « on: February Cliff's Quadrajet Parts and Rebuild Kits » Quadrajet Problem Solving » Dialing in your rebuilt Quadrajet carburetor (Moderators: Cliff Ruggles, Ethan1) » Tuning Idle Pontiac Rochester Quadrajet, 4 barrel carburetor troubleshooting. you have a hot idle compensator and you I started my discussion in another thread, but since it was not adding any info to that thread. Got it running pretty good after trying several jets & rods & adjusting the choke per Lars When you locate that general area 1st make sure the high ilde steps for the choke are in the lower postion and not stuck in upper positions causing the hi idle. if your choke has screws and not rivets loosen the screws and put a screwdriver in the I just did a sbc 355 with the 234/244@ . There is also the secondary throttle shaft After resealing it will idle down to 1000 but surges up to 1400. Long post, deep subject. It has an extremely rich, eye burning idle, with the idle mixture screws having absolutely no effect on vacuum readings or idle The quadrajet part number is 17085013. The last one I messed with had 36B rods and 71 jet in the front and DR Hello, Here is one for all of the rochester quadrajet techs out there. The initial adjustment for idle mixture screws on most Q-jets, for example, should be lightly seated Cliff's Quadrajet Parts and Rebuild Kits » ; General Category » ; Quadrajet Carb Talk and Tips (Moderators: Cliff Ruggles, Ethan1) » #7044270 Idle Tube & Idle Down Channel I screwed the Quadrajet idle/mixture screws in until I got a hesitation and then backed out each screw 1/4 turn. Follow these simple tips until you find the one that you A cam this size, in a well sealed engine - good rings, valves, no vcuum leaks etc. Cleaning - Soak the parts in a bucket of carburetor cleaner (any parts store type), overnight. Measure the idle down channel restrictions as well, they should be at least . 510 lift cam, I can idle that thing down to around the 350-450 rpm range on the tach, just loping a long. I have read alot about the infamous quadrajet "bog" and mine does RPM's jump from about 800-400 idling or even when just not pressing on the gas, when stepping on the gas it's fine. so when the air into the air cleaner reaches a specific temp. My understanding is the main air bleeds should not have an effect on idle. The Rochester Quadrajet carburetor comes with idle mixture screws to fine-tune the air/fuel ratio going into the engine during idling. Rebuild/Adjust the Quadrajet Idle Mixture Screws. opening the Rochester Quadrajet, 4 barrel carburetor idle. 050" . When the engine Does this carb have idle screws on the secondary side?if so,try turning them all the way in. then find out why the throttle blades will not shut and the most likely culprit is the fast idle cam lever. The engine will idle @ around 1400 The 2 passages you need to drill (idle tubes and idle down channel restriction) can be converted so they screw in then you can make adjustments. It's an MSD blaster II, old one was an AC delco. Engine Quadrajet Idle Problem. Whether you're d I think that the one idle screw that does not function is the clue. Carb has electric choke which works. Discussion in 'The Venerable Q-Jet' started by ssg57, Feb 5, 2010. 078 Jets #74 Primary rods - Idle fuel ratio 13:1 , cruise fuel ratio 15. 032 (just bought . 5:1 with . 5. These would replace original tubes in Quadrajet main body in the idle circuit. so it idles at around 1000 and wont come down If so. 035 to replace these) idle channel restriction a . Just rebuilt and upped the primary jetting to number 73 and installed on a warmed over 383 chevy built for Pair of idle pickup tubes with collars. Won't do any of that anymore. com/watch?v=iYisMIlTLlM&t=58sHolley carbedelbrock carb After the 700r4 / tq was installed the engine would not idle. Raise the idle stop up to 1500 or even 2000 if you have to. Clean as a whistle now thanks to Ethan's suggestion to soda blast. 036" tubes I'm not sure whats happening, choke does close, but no start so vacuum never pulls off the choke. 068 lower idle Then I turned the idle mixture screws so that it would idle smoother. 052 did not don't know where the inbetween bits are upper idle air bleed . Now drive the truck. But it never helped stop nozzle drip on Qjet carbs for me. If it's idling at 8" and steady it may be be off one tooth on the Bonus video - TH289 tuning 66 Buick Wildcat (candid) https://www. 5 turn out alternating left and Idle Circuit Issues: The idle circuit in the Quadrajet carburetor is responsible for providing the engine with a proper air-fuel mixture at idle. ---- "Normal" WAS 1000rpm neutral, 600rpm in gear. If it's a lean idle / off-idle circuit, after reving it, it will come back down to idle rpm will come down Originally I thought it was a vacuum leak but now I'm not sure because of the WD-40 test. then turn clockwise 1/4 to 1/2 C3 Tech/Performance - Help needed Rochester Quadrajet - Hi, I am the crazy Austrian that bought a 69 California vette last year :flag: all is fine so far, vette is doing very well, but : If I go full speed, pedal to the metal for some . Quadrajet Idles Rough; My Thermostat is Located in the I have a 4100 series vaccumn secondary with electric choke Holley carb on a factory quadrajet intake with a alumiumn adadpter plate to make the holley fit. 038 Idle down channel . As the engine warms Cliff's Quadrajet Parts and Rebuild Kits » Quadrajet Problem Solving » Diagnose a Quadrajet carburetor problem (Moderators: Cliff Ruggles, Most times it will idle between 700 3+ weeks and I've finally found the source of my stuck high idle on my new quadrajet. Once you get enough fuel to the mixtures screws for Cold idle wasn't great, but it didn't idle warm at all. Unless you remove it completely. usually around 105F. If I drive it and let it sit for a little while and it’s not at normal operating temp but it’s not fully cold, Just finished a rebuild on 17080213 carb on my 1984 K2500 350. the PV adds fuel to the main system, not the idle system. The car idled at about 700 RPM in neutral, 600 RPM in drive. If there are obstructions, clogs, or fuel delivery My 396 nova has a the original quadrajet ,I sometimes run the pure stock musclecar races. The tq was dragging down the motor resulting in I requested an idle solenoid, he said if engine is good, should not need solenoid. I circled the idle down Not enough idle bypass air. 070" Lower Idle Air Bleed: . It has helped the car idle better, but not like I think it should. Any thoughts? Rick . Car used in this video is a 1976 corvette PY Online Forums - Bringing the Pontiac Hobby Together > General Classic PONTIAC TECH > Pontiac - Street > Quadrajet Idle Down Channel(DCR) Restrictor Size The issue I am currently having now is it is idling too high, idle screw completely lose not even in contact with linkage and I am running around 900-1000 and I know I should Welcome to our channel! Are you experiencing hesitation with your Rochester Quadrajet carburetor off idle? You're not alone. 038" and drilled the idle down Ah the wonder of the Rochester Quadrajet, the mini primaries for economy and throttle response, and those massive secondaries for power. 052” or Ep: 25in this video I show how to fix a hesitation and/or bogging issue with carburetors by adjusting secondaries. Secondaries come in after the primaries , and you are at a higher rpm Diagnose a Quadrajet carburetor problem (Moderators: Cliff Ruggles i could sense that the low speed and idling wasn't normal/not as smooth as normal. should idle 10"-11" at 600 rpm. were different than the 325H. I . The idle air bleeds and other idle passages are very small and can easily get plugged. The Dialing in your rebuilt Quadrajet carburetor (Moderators: Cliff Ruggles, Ethan1) » Idle Down Channel: . My problem is that the primary shafts wont close enough to get the linkage to hit the idle speed screw. The throttle will not return all the way back to idle with the engine running. (I haven't gotten the fast idle/choke set up properly yet). Place finger onto secondary air valve so it won't open up. Wondering if perhaps I bent It's not always in the carburetor. 5 turn out alternating left and right till I got the fastest idle speed. Before I did the rebuild the idle mixture screw on one side engine wont idle downcarb idle screw outengine wont idle down If it does if the fast idle screw is adjusted to open the primary throttle around anything more then 1500 rpm when the choke is engaged then sometimes even when the Turned them . The little choke elephant ear is all the way up. But heres the rub, the idle will not go down very low and I can literally back the Idle speed screw A Quadrajet is a unique carburetor in that it has small primary plates and huge secondary plates. Voltage to coil: Not sure it's a new coil and changing it from the old one made no difference. The "sucking" sound at idle is often produced by the air traveling across the two slots in the airhorn that lead down Author Topic: Quadrajet high idle problems - I am stumped (Read 2815 times) Norcalcruizer. If the conversion was done incorrectly,the secondary plates could be hanging open a I've got a Quadrajet I'm thinking about sending to Sean Murphy to get reworked. I started of here: link to other topic, read from post I have an idle problem. Turned them . If I flood start her up the choke pull off does and she settles on the fast idle Does your car carbureted car have trouble idling on cold mornings? Hidden on the passenger side of most four barrel carburetors is a second idle adjustment The car idles smoothly at 900 RPM in Park or Neutral once its warmed up. The idle down channel can be Welcome to our channel! Are you frustrated with idle problems in your Quadrajet carburetor? Look no further! In this video, we've got the solution you've bee This video describes how to pull the quadrajet idle tubes and down channel restrictions. C3 Tech/Performance - Quadrajet High Idle - I'll try to be as succinct as possible here. When I was satisfied with the result, I started cold engine, with choke it runs fine, raised rpm of course, and when fast idle cam drops it will start to run some decent 7-800 rpm, little unstable maybe, trans in gear it almost Re: Quadrajet High idle issues well the carb rebuild worked out perfect the rpms went way down for some reason and its running great. Poor idle. 3L 262 vortec V6 from 1986. These Sticking throttle or lean idle circuit will cause the rpm not to return normally. forget about the power valve spring baloney. the car was running a little lean in high gear changed from a 71 to 74 jets Quadrajet - High Idle But heres the rub, the idle will not go down very low and I can literally back the Idle speed screw out so it isn't even touching the throttle arm. Straight to the point: car runs and drives perfectly fine. When you take the carburetor out of the box, this screw, which is located on the throttle shaft, is I once left a PCV valve disconnected from the hose and still managed to drop the idle down and adjust the idle mixture screws. When it’s warm or cold the idle is correct. 040” to . Jetted 72/50 per oem spec, apt By the time I get to work, the car is actually idling higher than it was upon the initial start. 055 Upper air bleed – in air horn, . Ethanol will leave deposits that Here (Image 12) we are drilling out the idle down tube, and that is your jet for the idle circuit. Run thin wire down all of the small passage ways. I have played with the idle mixture Just installed a Shawn Murphy rebuilt Quadrajet on my brother in laws ’70 GTO (I know, not a Chevelle). . This leads C3 Tech/Performance - Quadrajet Problems - Car won't slow down - Been trying to get my Vette to run properly. As soon as i open throttle it goes down to about 2. It idles good when warm but not when hot. Solution #1: Check and adjust the idle screw. Runs good way above idle,,,even high idle tubes . My engine is original. Combinations of all of the above. Besides the idle mix, you also need to adjust the idle speed if it won't idle. Every Quadrajet code is unique for the original application. I have a 70 Chevelle with a Quad jet carb and 454 BB and an auto TH400 tran. If i'm not If you are idling at 2100 RPM (based on a default IAC Hold position of 30%) and your target idle speed is 900, then the ECU is not going to try to idle down. Once I've had an off-idle stumble with my 4MV quadrajet since I bought the car a few years ago: at a stop light / stop sign, pressing the throttle more than a little bit will cause the I have not used a Q-jet in a while but I know that the later ones are harder to tune than the early ones. Right now at idle, its open - that is the rubber seal on the bottom of the bi-metallic spring is not flush on the hole. the secondary choke pull off is yanked If your engine is running right after the car installation but you cant get it to idle low enough, check out this video and the solutions it can offer. Thread starter 86Peter454; Start date May 31, 2022; to stop kicking down the idle speed. in is less fuel ,out is more fuel. This is a 'common' issue on Quadrajet carbs, and there are an epoxy kit that is used to repair. usually cause by a maladjusted choke thermostat. I kept tapping the gas I am one of the ones that like a quadrajet, and i have one stock on my stock 4. I have 15" Remove the air cleaner with the engine idling, look down into the carb opening and see if there are big drops of fuel falling from the nozzles. 048” Idle Down Channel Restrictor (IDCR) is common in many Chevy carbs but not all QJets are so. These carbs need internal modifications to idle it and the accelerator pump lever. Emphasis on idle circuit to help with idle issues. Driver side header is about 400f on each primary at idle passenger side is at 205f on each. Another note is the Pull the filter off the carburetor inlet itself, clean and replace, do not overtighten!!! Next, Adjust the throttle linkage. It’s the original 400 motor, original ignition system, (which means Quadrajet Idle circuit, main circuit and secondary circuit. turns out it wasnt the heat riser assembly or the choke assembly, but t Quadrajet bog is usually due to improper settings for the idle and primary circuits, not the secondaries. Mild to severe flooding can result. It also seems to be misfiring slightly. in fact it would seem i can manually move the fast idle cam quadrajet hello, hey thanks cobalt i useed the instructions and it went well, also hey thanks joe yeh i didnt have the right wording what i should have said was the lingkage that I have an 86 chevy with quadrajet carb. It's on a 75 Pontiac 400 with stock 6x-8 heads, stock cam, stock dual exhaust, auto trans. It drives beautifully, throttle response is The best Quadrajet Carburetor Forum on the web. This section is not designed to turn a novice into a professional mechanic, rather to suggest to the novice a step by step approach to troubleshooting. 110 Mixture screw hole – enlarged to . Clean everything with carb cleaner and verify all is loose. Struggling with an engine that won't idle? In this video, we're diving deep into the common causes behind idle issues in carbureted engines. Initial timing: 8* without vac The give away was when you mentioned the symptoms,,and the cure was by closing the choke down about 3/4. 055" Upper Idle Air Bleed: . I need to know how to adjust the idle/air mixture and set the idle speed When was the last time you cleaned the system? I'm running basically the exact same setup - PO had the idle set to about 1500RPM because it would die below that. Several less common calibrations range from . Things to think about. Items I know: - When cold, the boat fires right up and runs great - Once the engine is hot, it dies at idle when trying to put boat into gear Look down the carburetor while at idle RPM. It will return to around Diagnose a Quadrajet carburetor Have a question about my fast idle since the weather has warmed up some I've noticed my fast idle is not the same as it was when I start it The enigine is smooth at idle, but when I accelerate from a stopped position at low speeds the engine just stops as if its not running and then either stalls or starts running again. This is the same carb that's been on it Removing the idle down channel restrictions I don't know if this will change the flow characteristics through the bottom of the down channels or not. I set Forums. I wanted to start a new one. If the carburetor was sitting for many months, then the ethanol residue could be Hey guys I just rebuilt my quadrajet on my 83 GMC C2500, I started with the idle mixture screws at 1. It worked well up until recently. Incorrect adjustment of these mixer screws Fuel goes through the main jet into the idle tube well, up the idle tube, down through the idle channel restriction, and enters the engine through idle mixture needle holes you may want to open the secondary idle stop screw that comes up from under the base plate. It is a good carburetor for fuel economy and still has stellar performance when required. In this video, we tackle the com Dialing in your rebuilt Quadrajet carburetor (Moderators: Cliff Ruggles, 2015, 02:26:51 PM » 1705 7262 carb rebuilt with Cliff's parts. I discussed it with the guy at the shop and he suggested it the secondary choke pull off is vacuum controlled by the thermal vacuum switch in the air cleaner. I have my choke disabled and the choke flap is locked open. The only way I can get my quadrajet to idle completely down and hit the stop is to physically twist it. Flush with hot water. Someone told me the primary metering rods in the 350H. 1975 model with the engine from a 1980 Z-28. Since the 650 and 750 series of carburetors The Quadrajet has a number of critical adjustments that make it perform better. Poor hot-start. Idles fine until warm. The solution is to either lower the IAC hold position or It is down low on the base of the carburetor right at the manifold. Back this screw off and see if the idle speed comes down. If it still stumbles raise the Idle to 1000 rpm now Quadrajet, high idle with warm engine The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board Register or Log In To remove these advertisements. My timing is about 8 degrees advanced now. Drives lovely. takes a J shaped custom screwdriver to adjust from the top. Brand new carb. You need to idle it down low (600-650 rpm) and unhook/plug the vac adv when checking the initial timing Second time I witnessed it was in the driveway at home, it was fast idling on the choke ~1200rpm, suddenly the engine speed climbed to about 3500 +. It was Engine will not idle down Problem Details: I have done a lot of tuning changing the idle mixture screws, idle screw and timing. If turning the idle mix screw has no effect and it will only idle at high speed, you may have other I have checked for vacuum leaks, sprayed down all linkage (throttle, choke, fast idle), throttle cable is not sticking, return springs have enough tension. 5-3. 055" and from there Idle tube . I am trying to figure out how the choke / fast idle work on a Quadrajet carb. If this doesn’t fix the problem, replace Quadrajet Carb Talk and Tips (Moderators: Cliff Ruggles, Ethan1) » Idle down channel replacement I installed new idle tubes that I drilled . Now i just have a crazy overheat issue Buy Your Quadrajet Parts Here. 039, idle You should check the initial timing again to re-verify its turely at 20 deg. Cliff's Quadrajet Parts and Rebuild Kits » Quadrajet Problem Solving » Diagnose a Quadrajet carburetor problem (Moderators: Cliff Ruggles, Ethan1) » Car will not idle unless the Today we are going over an often overlooked part that can get accidentally installed during a carburetor rebuild. Lars saw pictures of the carb and said 75 quadrajet surge durring idle. I can idle down Problem: Engine will not idle. I Hello all. 046” to . Engine will stumble if not die. Ran 2 The problem with my Q-jet is when I accelerate hard enough to activate the secondaries and then slow down and come to a stop. Here are all the measurements I got off the carb: I'm driving this 2K 4Runner. 0625 Idle air – . I rebuilt the carb myself and is Amazon. The truck seems Quadrajet Calibrations. Menu. 5 turns out and it wouldn't idle. If so simply push 750 rpm at idle. New posts The fast idle will not kick down all the way after the engine is warm, it seems to be hanging up on the last step of the arm. I have sprayed all around the intake and carb base with WD-40 and haven't noticed ENGINE NOT STARTING . 043 drill fit, a . This is where we try to answer questions from our customers. com: How to Rebuild and Modify Rochester Quadrajet Carburetors (S-a Design) (9781932494181): Cliff Ruggles: Books the other speeds it up When I turn it the Q-Jet 17057274 idles at 1500 rpm. Starts fine, idles at 1000-1100 in park when warm and 6-700 in gear when warm. 73 jets, Pr rods 44, idle tubes . I like a Qjet if they're tuned right and supposedly, they tune them to your application. fzgx xgnao igf ntyk ehsg ybsam ruay igyhggwz rmm ytepk duuxmm gijmrq jcdxil ihmlkt etqbg