slight hesitation issues
07-15-2009, 12:39 PM
#1
Staging Lane
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slight hesitation issues hey all. ive got a non-LSX powered 87 formula. its a 305 4 barrel with an edelbrock 600 carb. ive noticed since i put my new fuel line on that its been hesitating just a little off the line. now, i did make the hose a little longer, due to trying to keep things clean and out of the way for show purposes. could this be causing my hesitation???? a fuel line thats maybe 2-4 inches too long????? any ideas??
Also, my air filter seems to get really dirty real fast. i noticed some residual fuel spray when i turn off the car, prolly whats getting the filter dirty. any ideas on this one too??
thanks!
-chris
I want to try and get these issues cleared up before the guy buys the car. :-)
Also, my air filter seems to get really dirty real fast. i noticed some residual fuel spray when i turn off the car, prolly whats getting the filter dirty. any ideas on this one too??
thanks!
-chris
I want to try and get these issues cleared up before the guy buys the car. :-)
07-20-2009, 12:19 PM
#3
the fuel line is not causing the problem,
your air filter getting dirty is most likely due to the dusty/dirty environment the car is operated in. Do you have a radiator fan driven by a belt off the crankshaft? if so, then it's most likely pulling dirty air in all the time and blowing it up at the air filter. Do you have a fan shroud around the radiator and fan?
if you're getting fuel spray out of the carb onto the air filter, without seeing it i would guess you have your timing a little too advanced and the mixture a little too rich for idle so on shutdown your getting a little reversion up through the intake and out the carb, almost like a backfire but without the fire. This is also caused by whatever overlap your cam has, higher overlap or tighter lobe separation angle (LSA) means your intake valve starts to open before the piston reaches top dead center on the exhaust stroke. When the tune is not optimal and when the motor is hot, on shutdown this reversion can happen and can be somewhat normal, it all depends on what your setup is which you didn't completely say. So i would look into what coolant temp your engine is running at when you shut down, what cam you have and is it installed straight up or is it installed a few degrees advanced which would increase the reversion on shutdown? And check your timing at idle and carb idle mixture, if anything lean the mixture a little, and also check the carb float level. checking fuel level in the bowl, or the float setting, is always step #1 in tuning any carb because it affects everything!
With hesitation off the line, that's most likely a lean condition, and they have simple troubleshooting steps in the edelbrock carb manual which you can download online from them to solve it.
your air filter getting dirty is most likely due to the dusty/dirty environment the car is operated in. Do you have a radiator fan driven by a belt off the crankshaft? if so, then it's most likely pulling dirty air in all the time and blowing it up at the air filter. Do you have a fan shroud around the radiator and fan?
if you're getting fuel spray out of the carb onto the air filter, without seeing it i would guess you have your timing a little too advanced and the mixture a little too rich for idle so on shutdown your getting a little reversion up through the intake and out the carb, almost like a backfire but without the fire. This is also caused by whatever overlap your cam has, higher overlap or tighter lobe separation angle (LSA) means your intake valve starts to open before the piston reaches top dead center on the exhaust stroke. When the tune is not optimal and when the motor is hot, on shutdown this reversion can happen and can be somewhat normal, it all depends on what your setup is which you didn't completely say. So i would look into what coolant temp your engine is running at when you shut down, what cam you have and is it installed straight up or is it installed a few degrees advanced which would increase the reversion on shutdown? And check your timing at idle and carb idle mixture, if anything lean the mixture a little, and also check the carb float level. checking fuel level in the bowl, or the float setting, is always step #1 in tuning any carb because it affects everything!
With hesitation off the line, that's most likely a lean condition, and they have simple troubleshooting steps in the edelbrock carb manual which you can download online from them to solve it.
07-20-2009, 02:34 PM
#4
Staging Lane
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wow! Excellent information. thank you! i do have the timing slightly advanced, seems to run better there for some reason. whatever cam is whatever GM put in the LG4 motor. i also have a 1" spacer plate under the 1406 edelbrock carb. I havent tuned on a carb car in a while, like 6 years. il see if i can find the manual from edelbrock. i wasnt sure if the longer fuel line would cause an issue or not, some redneck in SC told me that, so i didnt read alot into it. theres part of the reason im trying to sell/or trade it out....tired of workin on a cabr car, rather an LT1 :-D thanks again for the info, excellent.
07-20-2009, 03:23 PM
#6
Staging Lane
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no, not on this car, that was a different car 6 years ago. i just tuned this one up new plugs (platinum) and wires, new cap and rotor, new distributor, MSD coil, etc etc. :-)
1406, 1987, 600, carb, carburetor, edelbrock, firebird, hesistation, hesitation, holley, idle, line, slight, troubleshooting, tuning
