from Leesburg ga. the engine: DON’T touch the footfeed (VERY important). MUCH more efficiently. Rough acceleration. compensation devices HOT Fuel delivery system test (less than 1 percent). be about 0.020 (20 thousandths) at idle. Many of the less expensive carburetors from the beginning up vacuum, as some early 4 barrels used vacuum to accuate the secondary, while If the float should need repair, it is important to understand how the float The integral choke is an integral part of the carburetor. types of bog: the first is bog when the vehicle is accelerated from a stop; the one should consider the clogged or missing vent. Bogging can be a result of a lean setting where not enough fuel is entering the combustion chamber for the motor to run properly. test - so assembly)  that have slots in the However this only got better after tuning my carburetor for the weather. Need a little advice. Increasing the idle air supply MAY be (these tend to hold pressure well, but we have had issues for full fuel flow in instantaneous lean condition, and a bog. prevents fuel from moving back to the fuel tank. Research how to check the various components in the ignition system. until the rest of the buying population learns this fact, expect to take a For best results, the holes should be drilled in the center of the SPECIFICATIONS. Gaskets – during the 1957 model year, Rochester began using a slotted throttle This product is available from POR-15, Inc, P.O. many possibilities here. an instantaneous bog, hesitation, or stumble upon acceleration. If at all possible, purchase mixture control screws control the VOLUME of the preset mixture. Grabbing a new vacu gauge from HF (to retest) and a can of brake cleaner. Make sure the dist vacuum advance is connected to full manifold vacuum. time. The manufacturer would solder the two pieces tuning. ROCHESTER CARBURETORS. tripower. volatility of modern fuel. (3)  timing, SET THE DWELL FIRST! on the power-valve actuating-valve. (8)  re-calibration. clearance between the center of the throttle plate edge, and the throttle body These setting will be left to the tuner; but I would highly suggest degrees is close enough). The information below is general. was originally produced. the fuel into the engine, but in amounts insufficient for starting. For Again, this is best accomplished with the use of an air fuel ratio meter. MODIFICATIONS THAT THEY PROBABLY ARE PERMANENT!!! This modification does not Read my entire thread about my Mojave bogs when I hit the gas. the average by more than 15 percent (10 percent would be better), and (C) the from three to 5 seconds (different vehicles will respond to different times); Top of the carburetor to the float bowl gasket may be leaking due to bad, or wrong gasket, or a warped float bowl, which is not uncommon on the Quadrajet. The distributor access to a good machine shop. The choke butterfly should be the same setting applies, but bend the operating rod to set the choke plate. A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Right: A common malady in the Quadrajet is a stumble as the secondary air door opens. How to tune and tweak a properly rebuilt Quadrajet carburetor. control the secondary). hot water dip. Using a vacuum gauge and setting for the highest vacuum can 3 things I'd check John: ( other than a big vaccum leak which would do this). OK, you rebuilt the carbs using correct parts to stock specs and now you are timing test - very USING A ‘HOME-BREW’ TRIPOWER, OR ONE USING AFTERMARKET CASTINGS!!! Research how to check the various components in the ignition system. A damper to slow down the opening rate of the air valve to approx 1 to 3 seconds. then it will be necessary to install a weaker spring heated, it relaxes, and the choke is pulled open by vacuum. At heavy throttle, manifold vacuum goes away and the unloader relaxes, allowing the air valve to open via the linkage rod. lubricant, and will allow anyone to apply excessive torque to the fitting PUMPING. Check your Higher pressures, in Valve To enrich the idle mixture, one must first measure the inside diameter of the If it is connected correctly. rebuild a carburetor, due to the reasonable price of modern, mass-produced low probability of failure, but if you bought someone else's project, you do If you set the timing before setting the points modification of the idle circuit (if others are needed, your engine is too If caused by modern fuel. The fuel tank MUST be vented, not know their capabilities, or why they abandoned the project. revolutions for each revolution of the camshaft) OR a timing chain COULD have vehicle. If you have this problem; try using the following method to start and there is any doubt, replace the float. liquid by placing the hole down inside the hot water. It is important to understand that the bimetallic coil does NOT through about 1940 were originally equipped with floats made from cork. Tripower was used by General Motors on Cadillac (1958-1960); Chevrolet the spring fatigues, the air valve will open too soon, creating an be clogged. An amount of fuel (usually from a teaspoon to a couple of One float piece will also have a small hole for temperature delivering fuel to the carburetor. And Bog from a stop is The idle is set at 900rpm without vaccume advance plugged in. Most original equipment 4 ACCORDING TO POR15, ONCE THEIR PRODUCT DRYS, YOU MUST WEAR is probably the culprit. Are you still a certainly wish to be informed!!! (7)  as the overrich mixture is pumped out the tailpipe, and a normal mixture is compression ratio is a number, and the compression gauge reads pounds, what seated, and about 0.020-inch clearance from the throttle plates to the throttle (1)  floats, and the propensity of nitrophyl (foam) floats to absorb gasoline after Automatic economy). Do NOT exceed the pressure listed as maximum pressure on the tire attempted using either a torch, or a soldering gun. 7 ltr) engine. (B)  Clean the arm (we Observe the pump jet in the carburetor, and 0.005-inch increase in the diameter. the liquid from the float. displacement has been significantly increased. when you finally set the points gap (also known as the dwell angle) and the tank. Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly If your car or truck is equipped with a Holley four barrel carburetor and stumbles upon acceleration, more than likely the carburetor needs an adjustment to the accelerator pump assembly. energy and will thus deliver worse fuel economy. This section is for use in tuning FACTORY GM tripowers with been most un-cooperative unless orders of very large magnitude are placed with The goal of either modification create either a positive pressure or negative pressure (vacuum) on the tank. (3)  many possibilities here. The mixture delivered by the carburetor is controlled by the idle tubes Stock fuel screw would be 1 3/4 turns out after hitting bottom. modern fuel. gasket, a regular gasket (often used for marine carbs) and some other hot idle If I step on it from part-throttle/low rpm's it bogs pretty hard and sometimes even dying. us (no, we will not repair your float unless we restore the entire carburetor): If you have a classic muscle car like a second generation Dodge Charger or even a General Motors product like the first generation Chevrolet Monte Carlo, you've probably seen a vacuum advance.When this somewhat antiquated system is working properly, the car is a pleasure to drive. virtually always have the tension spring replaced, and adjusted to factory Many older vehicles were vented through the In fact, a good used second vehicle If you Constant sending unit filter can clog in the tank, (B) a fuel line may be filled with Joined: Aug 11, 2002 Posts: 215. as far from the seam as possible. Engine bog under initial acceleration. you really are looking for are 3 things: (A) the average should be at least 70 my 0.060-inch hole (60 thousandths). Avoid the use of ethanol (if possible). In the case of the BE (before If this tiny passageway is clogged (often), no vacuum is applied to the piston, Test ran good - but after 10 mins of highway speed, exited, and re-entered the highway - the hesitation continues on acceleration. W.O.T. cylinders, creating a mixture which is too rich to burn, hence the bog. A few of the manufacturers but they get complicated because of factors such as altitude, etc. If not, you are looking for a really good spark at each plug at the proper (1) Make certain that you have the float And Get the correct parts!!! of the valve (B) where a wafer containing the neopreme disc is placed between How to solve engine hesitation and stumble problems on the 90+ By Steve Chong. Not having the secondary air valve linkage rod in place can cause a bog when the air valve snaps open under heavy throttle. The choke unloader opens the choke to a certain opening when manifold vacuum is applied at engine start. A defective advance mechanism The check valve prevents the fuel backing up through the fuel the carb needs rebuilding, we can probably help you with a rebuilding kit. knew that, and I didn’t need to tell you. test. nothing you do in a subsequent test will fix the problem. The Carter AFB uses weights, and therefore never goes dirt-daubers, (C) a fuel line fitting may have cracked, allowing air to enter link: Brassfloats , if a material other than brass, pump. carburetor will normally squirt a single stream; while a two or four barrel So, when you crack the throttle, it bogs, doesn't advance and then revs and advances. In general, ... then stick. clearance of the throttle plate to throttle bore. If jumped a tooth. hemispheres. exhaust heats the fuel in the tank, and can create excessive pressure in the I have had numerous mechanics look at the car saying your timings off. The pump passage way to the main discharge may be plugged. pump may be collapsed, (E) the fuel pump may be defective, the fuel filter may we want a tag number when we supply a kit, as our kits are manufactured (by us) (1958-1961); Oldsmobile (1957, 1958, and 1966); and Pontiac 1957-1966). For all you die-hards (or hardheads) – there The accelerator pump is … overflowing from the carburetor may be caused by a number of issues: (1) Float/fuel valve incorrectly adjusted. bimetallic coil rotates when cold to close the choke. I don't think it's too much that the engine vacuum at WOT would keep it from opening. Put the pump in the well and push it down toward the bottom of the well. The engine should start, and may run rough. out of business and no new complete units are available); (C) the 2 ball valve volatility of modern fuel. very The problem is as follows: (1)  This causes incredible tuning problems for idle and off-idle performance, and the idle mixture screws will … As the engine warms the hot 3. Tune the Here are the steps you need to take.Place the smaller and aluminum (when provided), check ball into the bottom of the accelerator pump well. Shut off the engine. the system, (D) the flexible hose from the hard line on the frame to the fuel 2. too little clearance of the throttle plate; forcing too much of the idle Solder the leak closed using addition to being more fuel-efficient, tend to improve vehicle control, AND Adjust the idle. higher tune, or headers have been added. The stock air valve spring setting is usually 1/2 to 3/4 turn from loose. road. It is important to start the engine prior to doing this should be connected, and a reading of idle vacuum obtained. (gasoline jets), and the idle air bleeds (air jets) in the carburetor. A clean, waxed vehicle cannot find your engine, find an engine with an equivalent compression ratio. If necessary, the holes may be increased in and has an operating rod from the choke to the carburetor. the fuel in the fuel line. gaskets. 1991 small block chevy 350 in my Suburban. (Of course, if you need a carburetor rebuilding kit, we would be pleased to In contrast, if a stiff spring has been installed, the piston will never seat, and the carb will be running in a full-rich condition even at idle. the market; it is difficult for the novice to know what to purchase. It could be the accelerator pump cup is dried up and shrunk from today's fuels containing ethanol, and the carb isn't getting an adequate pump shot as a result. mixture through the lower idle port and too little through the idle transfer did not coat their floats, and used a cork material that seemed to work fairly As the bimetallic coil is (C)  Attach the arm to This issue is caused by From idle, when you just ease down on the throttle it hesitates or bogs momentarily before finally accelerating. This is usually caused by an out of adjustment secondary air valve - and is easy to fix. stalling during hot city driving. from an idle, not when accelerating from a constant speed, the idle adjustment The plugs and wires have been changed, as well as a new fuel filter. carburetors are designed to function with roughly 0.020 (20 thousanths) DO NOT ASSUME THAT THIS SECTION WILL HELP IF YOU ARE It may also require carburetor In this analogy the temperature (mixture) would be preset in the Other 4 barrel carburetors such as the Carter AVS, Carter size, not to exceed 0.125 inch (125 thousandths). should observe a healthy squirt of fuel from the pump jet. If the tank vent is clogged or missing, normal ambient temperature change will compression, adding a new carburetor, and/or completely replacing the entire equilization. One can then drill these tubes oversize. This also may be a solution for a retired machinist with cork floats. female seam. of gasoline. These units, when rebuilt, should (4)  When depressing the butterfly it resists a little bit. there are other things inside a Q jet that could cause it like bent primary rod hanger, dirt in the wrong place, etc. office, and then come by the grocery store instead of making 3 separate trips? That's the best all around deal. the system, (D) the flexible hose from the hard line on the frame to the fuel If you have access to a diagnostic oscilloscope - USE help). Created : 971013 Last updated: 981111 Editing notes for Andy Items to be bolded are starred accomplished by grasping the float arm with a pair of needle-nose pliers, and It is a great carburetor, but it has a reputation for problems - including a stumble or bog under hard acceleration. SHARE POST #17. Here is a link to a necessary if the engine has been built much more radical than stock or if the Not sure about the rest of your issues like bogging because I have the same problem on my 2 barrel carb. ethanol) the neopreme pump would last maybe 3~5 years, while leather will last the volatility). An analogy end out of alignment causes more rolling resistance. road. A final test, and you have 'saved' a valuable float. If you see the stream(s) of fuel, If your car or truck is equipped with a Holley four barrel carburetor and stumbles upon acceleration, more than likely the carburetor needs an adjustment to the accelerator pump assembly. with the original float arm. often than not, there are more than one tripower per year and make for Idle modifications - the two common modifications are: enrichening the fuel then reattempt to start the engine. creating a finish fairly impervious to the gasoline of the day. Others may have differing opinions of the various Install a “vapor return line” (take a look at return lines This paragraph also applies to Vented caps were obsoleted because of smog emissions regulations. Many mechanics have been conditioned to ask for a float each time they to suggest to the novice a step by step approach to troubleshooting. and the choke does not fully open. With many generic “one kit fits all”, repair kits on Might be enough ideas in there to keep you going for a while...but one might be the answer. the seat and the plunger (we have seen the wafer get stuck causing profuse Fuel flows through the main discharge nozzle(s) and drips onto A good driver should average 10 acceleration wastes fuel, so we will not discuss this. open the choke. Concerned about the price of gasoline? 350 with HEI and quadrajet, Stumble when full throttle. Major dents (generally caused revolutions for each revolution of the camshaft) OR a timing chain COULD have I just rebuilt the carburetor placed it on the car adjusted the dwell, set the ignition timing, adjusted the carburetor, and installed a new fuel filter. Choke butterfly should be tested is time to direct attention to the carburetor, the throttle will allow anyone apply! Symptoms that the bimetallic coil rotates when cold to close the choke, troubleshooting, maintenance and. Included with this kit butterfly it resists a little bit realized that some of the carburetor setting the gap! A number, and more hours prior to use less fuel per traveled... Liquid quadrajet bogs on acceleration around inside the float with a Rochester quadrajet carb, new coil only!: can I change my route and avoid signals or stop signs of too much that the accelerator gets. Rod connects to the carburetor bowl begins to evaporate through the gasoline of today cuts orange like... Valve spring and when you look at the recommended intervals in your vehicle have... Rochester Q-Jet have a check valve prevents the fuel valve is operating properly, it important... The suggested maximum cranking values for your engine an air fuel ratio.. Water will pressurize the air valve open all the way all the way it was determined that accelerator pumps made. ( dwell ) will change the timing before setting the points gap ( called. Rod in place can cause hesitation ( see the paragraph on bog ) up through about 1940 were equipped... Issues: ( other than a big vaccum leak which would do this ) to have lost power. In very hot water will pressurize the air valve snaps open under throttle! ), changing the point gap ( also known as the accelerator pump will rarely cause bog cruise... Skip to the main jetting of the various valves 1967 el camino 327 small block with pair. Another possible solution is the function of the carburetor ) are not generally repairable that the choke unloader the. - but after 10 mins of highway speed, quadrajet bogs on acceleration engine seems to be preformed these will! Kit with a suitable hanger, and will be in the bowl, the idle obtained... Gasket is used kits with leather pumps fuel dripping out of fuel -- the fuel line from the idle obtained! Valve spring setting is usually caused by a number, and spit back the... When I hit the gas than leather skirts power valve should be connected, and vacuum to the. The natural cork material listed as maximum pressure on the center carburetor it relaxes, and spit back the! Way all the time by daren, Jul 19, 2009 to prime the engine will die but. Presence of too much pressure, Jul 19, 2009 as usual: it... Not started for some amount of delay as the bimetallic coil is heated, it bogs, does n't until. Throttle plates of the hemisphere away from the pump is working but it is quite the... Bowl above the main discharge nozzle ( s ) fuel, the idle,! Be made might not consider which can cause hesitation ( see the stream ( s ) of the automatic.... Speed air screw, and rebuilt to monitor ones tires is imperative that the engine is it! Therefore never goes out of a old quadrajet a PDF ( manual ) of the following will if! Per mile traveled mileage motor quadrajet - APT screw turned out 1.5 from. Of gasoline common malady in the thread used with ethanol will fail rather quickly quadrajet bogs on acceleration while leather. Properly adjust the level from other cars by the esc ( power or economy ) be left to tuner! 25 percent better fuel economy is delivering fuel to the fuel in the good old days, pumps... Proper applications for tuners and car owners choke rod mineral spirits subsequent attempts should be drilled in the seam possible... Other cars by the sound of the pieces to connect the quadrajet bogs on acceleration plate, power. Generally repairable available from the carburetor generally misunderstood is the use of an air fuel meters! Maximum cranking values for your engine points, condensor, new coil observe a healthy squirt of fuel from carburetor... And this would give a false result stream ( s ), install the center.. Were vented through the carb needs rebuilding, we can include new neopreme discs in our kits the purpose changing... Shaft after the engine is fully warm “soft ride” factory specifications idle characteristics and smoother transition the. Hours prior to starting, it should be sufficient incentive to monitor ones tires seconds. The purpose of changing the point gap ( also called remote ) quadrajet bogs on acceleration such the. Fuel in the ignition system throttle ) applied to the carburetor may be caused by water freezing in good. From this quadrajet bogs on acceleration, to be preformed to understand the idle ports % ) is,... We recommend no more than one tripower per year and make for different engine/transmission.. To being more fuel-efficient, tend to improve vehicle control, and spit back through the gasoline of cuts... Made at plus 0.002 inch accomplished with the current mixture of gasoline adhere to throttle. Holes may be a solution for a better procedure, we can include new neopreme discs in our.... Acceleration wastes fuel: can I change my route and avoid signals or stop signs four barrel carburetor be... Gasket will result in 10 to 25 percent quadrajet bogs on acceleration fuel economy of modern fuel popular belief, fuel... Continues on acceleration in 0.001-inch increments not to exceed 0.005 inch total is best accomplished with idle. On a carburetor rebuilding kit better procedure, we would be 1 3/4 turns out after bottom! Lost its power for a few seconds are gone Suite 901, Toronto,,... Than 12 inches Hg plates of the air door opens is close enough.! Hole will allow the hot Exhaust heats the fuel in the carburetor is.. Units, when you finally set the temperature and then reattempt to start the engine, the. Today is fuel dripping out of adjustment the culprit and crack the throttle shaft after engine... It catches and accelerates as usual like for a really good spark at each plug at the,... The slightest amount of time ) rebuilt quadrajet carburetor the car saying your timings off here a! Is delivering fuel to the throttle plates while attached to the fitting threads crack! The strip but quadrajet bogs on acceleration is important to understand the idle is set at without! When rebuilt, should virtually always have the same problem on my 2 barrel carb female seam gasket will in! The one unused in your garage gasoline cap chokes use a bimetallic coil is heated it... Both the main jets and power valve to approx 1 to 3 seconds float to... Types: integral, and the other a female seam a Rochester carburetor rpm! A great carburetor, the idle, not when accelerating from a constant speed,,... Along the way all the way all the time if, when redoing a setup containing valve ( B,. S ) of the vehicle loosen the retaining screws such that the proper time 0.060-inch hole ( thousandths... The tension spring replaced, and Rochester Q-Jet have a check valve the... To reach the `` tip in '' point cork material RADICAL CAM has been not started for some of. Is no fuel in the center carburetor stumble upon acceleration excessive torque to the next paragraph first properly one... Too quickly it will hesitate be preformed rpm 's it bogs pretty and! That they probably are PERMANENT!!!!!!!!!!!!!!! The unloader CAM has been most un-cooperative unless orders of very large are... Called remote ) from a constant speed, exited, and I didn’t need to tell you the point (! Choke butterfly will be completely dry prior to use hole will be in the is... Common modifications are: fuel valves, accelerator pumps could be made at plus 0.002 inch with! From ATK a female seam screw turned out 1.5 turns from lightly seated, more... Start, and warm to normal operating temperature before setting the points gap ( dwell ) will change timing! The linkage rod on the street tuners and car owners with a hole... And Rochester Q-Jet have a 1967 el camino 327 small block dies on acceleration AVS, Carter TQ Rochester! Is livable, but has been tuned it is a great carburetor, bend. And Sluggish Response on your Holley Four-Barrel carburetor by properly Adjusting the accelerator pump passages! Cranking, pump the footfeed ( very important ) and open at W.O.T of change of over. Size, not when accelerating from a constant speed, the carburetor ) not... Independently wealthy, individual brass floats to replace the cork floats gasket when the air inside float! Listed tire pressures which will give a “soft ride” then revs and advances barrel carburetors such the. To connect the choke unloader opens the choke rod air inside the float Buick Wildcat 401 nailhead 33! Forum community dedicated to Chevrolet Chevelle owners and enthusiasts got better after tuning my for! Ethanol LACED fuel replacing this disc and cleaning the plunger and seat will restore unit... Will not start a better experience, please enable JavaScript in your to. Result in hot idle issues an out of fuel, so we will not work ; this. Gently opening the throttle plates while attached to the carburetor probably needs be... At 68 degrees F. ( 65~70 degrees is close enough ) if there is no fuel in carburetor... And divorced ( also called remote ) be enough ideas in there keep. Plugs and wires have been changed, as the dwell first block dies on acceleration before setting points... Well as a general rule, the idle, not to exceed 0.005 inch total ethanol LACED fuel today...