I was thinking the accelerator pumps were adjustable on these carbs,,,, The linkage that hooks up to the plunger has different holes to control the plunger travel, if it is set short, the accelerator pump wont give it a big shot of fuel when the 4barrel opens,, leaning it out, The pump should be set so the plunger moves as much as possible in my opinion,,, so the plunger has the full travel it will allow to move,,, That way it give it a bigger shot of fuel into the venturi of the carb when the gas is mashed for acceleration. OR,, it could be geting too big of shot of fuel when the plunger is activated and cause a stumble cause the fuel is not mixing up with the air quick enough,,,, Id bet on it being lean on the pump shot,,, if the pump adjustment dont help, then look at the size of the jets,,, I have went out on the street, and ran it hard, and then shut it off as quick as the engine came back to an idle,,, then pulled out the plugs to look at the plug color,,, if the plugs are white or very light brown, it may need more fuel,,, I like to see a nice cocca brown plug when the engine is under a load, that tells me its getting enough fuel,,, if its black or very dark,,, its getting too much and needs to be backed off,,,, Also,, maybe the distributor advance is not up to snuff,, if it moves slow or the springs in the advance are too stiff,,, the timing wont change quick enough until a radical rpm increase is enough to throw out the weights to change timing for rpm increases,,, Maybe find a recurve kit,,,, put lighter weights and springs in the mechanical advance in the distributor,,,, JMHO,,,, ChadS
ST, that is EXACTLY what mine is doing!!! The "BURP" is a great description. Then after the burp, all the power I can handle. I notice mine mostly at takeoff, since I seldom downshift to accelerate (I now have enough torque to accelerate pretty smoothly and quickly without downshifting). I may try that downshift next time out. Also, I just rejetted as well. I think you and I both have the same carb. As for the plug color, I am really happy with the light tan color since re-metering the carb. Still a little lean, but not lean enough to do any damage. I will have to look into that pump adjustment. By the looks of the thick healthy stream of fuel when I pump it, I am almost of the opinion of the 2nd suggestion, where it is trying to "flood" the carb due to poor atomization and too big a shot. That might be the reason for difficulty starting, as well, flooding the carb when I pump in the morning to set the choke (I floor it once or twice slowly, to let the choke flip over and catch the accelerator cam). I guess I will either get out the edelbrock instructions on that acc pump, or call them up. They are usually good to deal with on the phone, from past experience.
Do you see immediate squirt in relation to linkage movement? There should be an adjustable amount of lash between the beginning of linkage movement, and actual squirter arm contact. If this gap is too wide, obviously the car will fall on its face, or hiccup until the linkage contacts the squirter arm and shoots it the fuel. Just a thought.
How about engine temperature, could be warmer when driving it in 2nd gear for your distance. There are transfer slots above the butterflys that if exposed at idle can also cause a hesitation. The purpose of these slots is to richen the mixture off idle. They become exposed when the butterflys are opened too far to raise idle speed for a larger camshaft, retarted timing, removed PCV valve, etc. When exposed the idle screws are commonly leaned out to compensate for the fuel being pulled off these slots. When this is done they no longer function as designed. If you have vacuum at the ported vacuum port at idle your throttle blades are open too far. Also check your power valve or power piston spring calibration, when running a large cam you may not have enough vacuum to keep this system closed at an idle. When running an automatic your power valve/piston should be about 2" Hg lower than your engine vacuum at idle in gear. Hope this helps! _____________________________________Rocky
i have played with the plunger and have not noticed any improvements... if i think about it right now.. i am at the closest position.. which allows for the most movement.. the next thing i could i guess is play with the springs.. allow the secondaries to open soooner... giving it more gas..
Have you tried calling the Edelbrock tech line at 800-416-8628 or sent them a message at edelbrock@edelbrock.com
to each his own, i have two hollys sitting on a shelf collecting dust. id go with the demon if i went away from edelbrock.
holley.... edelbrock... whats the dif i have heard so many different opinions.. what makes one better than the other?
A lot of it is preference. Next time your at the track walk around and see what everyone is running. (Other than the stock classes)
Im more of a holley man myself,,, But, passionate towards Quadrajet carbs,,, I know that sounds strange,, but hey,, I just like em. When they work right, they are awesome. The way I see it, you all have helped me with my maverick so much, I want to give back!! I sure hope I can help,, I have been working on engines for about 15 years now, dyno work, building, carbs, ignition systems. I have dealt with alot of performance problems, ya know, trying to make em run and run great, and I have had some good luck over the years with tinkering with all sorts of different engines. By no way, do I profess myself to be a professional engine builder, But, I do see alot of weird causes in why things dont work the way they should,,,, Most problems in performance, lay hidden,,, and you have to look for these signs to know what your engine is doing, to properly tune it. Im sorry for making this a long post, so bare with me, Im on my 5th cup of coffee, and Im revved up. LOL!! From my experiecne, hesitations upon acceleration come from many factors,,, From spark plug gaps, coils, carbs, fuel, distributors, etc etc etc. I love to look deeper into engines, looking at compression pressures, rpm ranges, fuels, carb sizes,,, plug color,,, If you have made adjustments that do not help, then maybe you should look a little deeper,,,, Here is what I do,,, First, I run a compression test on all the cyls,,, Pull all the plugs out, hold the throttle open, and crank the engine till the guage peaks. This is great when your have just built the engine, and have put a few miles on it to break it in,,, but sometimes,, the rings are not seated in, and will cause a fluctuation in cyl pressures,,, This, I have found to be the number one misdiagnosed problem in engine tuning,, That will throw off the engine so badly, that you may think that the timing could be off, or it would be a carb problem,,, really, it is both,, cause it affects both timing and carb performance. if you have a cyl or more than one cyl that is off by 15to 20 psi from the rest,, you have a leak, or the rings are not seated, it could push pressure down past the rings, or maybe a valve is not seated or adjusted, or a gasket is leaking, intake, or head gasket. The compression test will tell you lots of things!! it tells you how good of seal you have, high readings will also help determine octane in your fuel, where if your trying to run a high compression engine on 87, or 93, where it may need even more,,, Compression tests are kinda self explanitory,,, so lets move on,, Once I know the cyl pressures are up to snuff, I look at fuel,, Is the fuel hot enough? Does it have what it takes to run a high performance engine? Id so, I think of the ignition,,, Does the coil produce enough spark to fire a high compression, high rpm engine? if the coil is not hot enough,,, the spark, could be blowing out like a birthday candle if the coil is not hot enough, or the gap is wrong, or the heat range is wrong, which causes a quick hesitation upon quick acceleration. Next would be the distributor mechanical, and vacuum advance,,, vacuum advance is used to help the engine idle smoother,,, away from the base timing, it has to be moved to help the engine run a little better,, but really,, thats about all it does,,, but the mechanical advance is where throttle responce is greatly helped when it is modified. let me expalin,,, This is an engine control, which main function is to react to sudden rpm changes, by centrifugal force, the engine speeds up, the weights go out to change the timing to compensate the rpm change, if the mechanical advance is sticking, or the springs and weights are so stiff, its going to limit how fast the reaction time would be upon acceleration,, therefore,, it holds you back until whatever the weights do actually respond,, making the weights activate faster will change timing faster and help acceleration speeds. the time it takes from which you mash the gas and rpms start to rise, when the guys said that he downshifts to get the rpm up faster, well that throws a shock into the distributor advance and make it respond quicker from the sudden force of the weights moving outward. In mu opinion, they should be rpm sensitive in any situation, Lighter weights, and lighter tensioned springs will help the engine control respond faster in these circumstances, therefore, rpms rise faster. Now usually, when this happens, it creates a whole new problem,,,, the carb is thrown off because, now it cannot keep up, so factors have changed and now require carb adjustments to compesate you modifications, for every action, there is a reaction,,,, you increase compression, you increase air speed in the manifold, you increase throttle responce time because there is more force pushing down on the crank to turn it harder and faster,, thats where it really picks up torque that you can really feel. Everything working together to obtain one common goal, to get the engine rpm up to the level you want, as quickly, and as smooth as it can be, as well as agressively as it can be. Do I belive its a pump shot problem,, yes, kinda,,, but I belive it is more in the ignition, especially since you have a stroker that revs up faster than a stock engine would ever think about, Something is limiting your engine to the point where it is lagging or lazy till it really responds, then it comes out of it,,, Let me ask you this,,, If you was to slowly push on the gas pedal,,, slowly accelerate, bring in the 4bbl slower rather than mash it,, what happens??? bet there is no burp, or hesitation is there??? If there is not when you do the gas like that,, your looking at a engine control responce issue,,,, cause if it runs good when you slowly put the pedal to the metal, something is not responding fast enough under the fast hard mash of the throttle. Think about what Ive said,, cause usaully 9 out of 10 thats where the problem usually lies,,,, JMHO,,,, ChadS
