edlebrock carb
06-23-2006, 12:38 PM
#1
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edlebrock carb
A buddy of mine is running an edlebrock 600cfm carb and lately when it gets hot it started dripping fuel out of the primary's and dies at idle. it runs just fine when cold and doesnt drip, only when hot. Any ideas? BTW the old carb started it and he didnt want to rebuild it so we put a new one on and has the same problem. Thanks in advance for any suggestions, I am stumped[:@]
06-23-2006, 04:08 PM
#3
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RE: edlebrock carb
Edelbroke carbs are horrible. Hard to tune, hard to work on. Should'a got a Demon 600cfm. Best damn carburetors money can buy.
But im no exspert with carbs but it sounds like your running to rich when it heats up, jet it down or play with your idle screws when its hot to see if you can make it run, i could be wrong, someone please correct me if i am, just trying to help. Also, sometimes on my dads camaro his gigantic holley's floats stick open and cause fuel to leak every damn where. Most carbs come jetted a little rich, if its just a stock or mild 302, you'd be surprised about how little carburetion you actually need for them. I know someone running a 530cfm carb and the thing does fine...lacks a little on the top though.
But im no exspert with carbs but it sounds like your running to rich when it heats up, jet it down or play with your idle screws when its hot to see if you can make it run, i could be wrong, someone please correct me if i am, just trying to help. Also, sometimes on my dads camaro his gigantic holley's floats stick open and cause fuel to leak every damn where. Most carbs come jetted a little rich, if its just a stock or mild 302, you'd be surprised about how little carburetion you actually need for them. I know someone running a 530cfm carb and the thing does fine...lacks a little on the top though.
06-23-2006, 04:18 PM
#5
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RE: edlebrock carb
Here's something I found you can chew on for a little bit. Be patient man....
Excessive under hood temperature: Ensure fuel line is not located too close to heat sources such as the exhaust or block, causing expanding fuel to be forced past the needle and seat. Fuel can also boil inside the carburetor due to missing gaskets, spacers, or heat shields. Also check to see if the exhaust heat riser is stuck, allowing excessive heat under the carburetor. Use Edelbrock Divided Heat Insulator Gasket #9266 for dual-plane manifolds, Square-Bore Heat Insulator Gasket #9265 for single-plane manifolds, and #9267 Heat Insulator Gaskets for dual-quad manifolds.
Could be float level also but I'd be willing to bet ^^^^
Excessive under hood temperature: Ensure fuel line is not located too close to heat sources such as the exhaust or block, causing expanding fuel to be forced past the needle and seat. Fuel can also boil inside the carburetor due to missing gaskets, spacers, or heat shields. Also check to see if the exhaust heat riser is stuck, allowing excessive heat under the carburetor. Use Edelbrock Divided Heat Insulator Gasket #9266 for dual-plane manifolds, Square-Bore Heat Insulator Gasket #9265 for single-plane manifolds, and #9267 Heat Insulator Gaskets for dual-quad manifolds.
Could be float level also but I'd be willing to bet ^^^^
06-23-2006, 04:23 PM
#6
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RE: edlebrock carb
i didnt think of that...Grimace is the carb man....but yes gas boiling will do exactly that, had that happen on the camaro long time ago when it was just a little 327 car with a motorcraft carb on it.
06-23-2006, 04:25 PM
#7
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RE: edlebrock carb
Primary Main System: The Primary Main system delivers an increasing percentage of the fuel as throttle position increases (phasing over the Idle System) and varies fuel delivery in response to air flow and manifold vacuum.
Fuel is drawn through the Main System (Figure 3) by the pressure-drop that occurs when the incoming air flow must increase in velocity in order to pass the reduced throat areas at the Main Venturi (1) and the Boost Venturi (2). This pressure-drop (or suction) is communicated to the system by the Nozzle (3)-a brass tube that opens into the inside of the Booster Venturi (2).
The fuel must pass through the restriction at the Main Jet (4) and Metering Rod (5). The Rod extends through the Jet, reducing the amount of area available for fuel flow. If the diameter of the Rod is large, then fuel flow through the Jet is more restricted than if the Rod were small.
After the Rod and Jet, the fuel enters the Primary Well and is drawn up the inside of the Primary Well Tube (6). Sometimes this tube is called an Emulsion Tube. Here, the fuel is mixed with air that enters the inside of the Tube through a series of small holes. The air is supplied by the Main Well Bleed (7) at the top of the Main Well. The air/fuel mixture exits from the top of the Main Well into a passage that leads it to discharge into the Booster Venturi (2) at the Nozzle (3).
The fuel flow rate in the Main System is proportional to the air flow rate; as air flow increases - from either an increase in throttle opening or an increase in engine speed at the same throttle opening - the fuel flow also increases by nearly the same degree.
At higher engine loads, such as in a heavy part-throttle acceleration, there is a need for a
richer mixture. This enrichment is provided by the Metering Rod and Step-Up Function (Figure 4). A vacuum passage (8) communicates the manifold vacuum to the underside of the Step-Up Piston (9). This vacuum tries to hold the Piston in the bottom of its bore by working against the force of the Step-Up Spring (10).
When the manifold vacuum is high, indicating a low load such as idle, cruise, or light
acceleration, it is able to overcome the force of the Step-Up Spring and hold the Step-Up Piston at the bottom of its bore, which also positions the Metering Rod at the bottom of its travel. At this point, the Rod has a large diameter that creates a high restriction through the Jet and the fairly lean A/F Ratio that is desirable for low load/low power operation. This portion of the Metering Rod is referred to as the "Lean Step" of the Rod.
When the manifold vacuum is low, indicating a high load such as a heavy part-throttle (or WOT) acceleration, the Step-Up Spring is able to force the Piston to the top of its bore and position the Metering Rod at the top of its travel. This action is called "Power Mode Staging". The portion of the rod now located in the jet has a smaller diameter, thus the restriction through the Jet is reduced and a rich A/F Ratio is provided for high load/high power operating conditions. This is the "Rich Step" of the Rod.
Fuel is drawn through the Main System (Figure 3) by the pressure-drop that occurs when the incoming air flow must increase in velocity in order to pass the reduced throat areas at the Main Venturi (1) and the Boost Venturi (2). This pressure-drop (or suction) is communicated to the system by the Nozzle (3)-a brass tube that opens into the inside of the Booster Venturi (2).
The fuel must pass through the restriction at the Main Jet (4) and Metering Rod (5). The Rod extends through the Jet, reducing the amount of area available for fuel flow. If the diameter of the Rod is large, then fuel flow through the Jet is more restricted than if the Rod were small.
After the Rod and Jet, the fuel enters the Primary Well and is drawn up the inside of the Primary Well Tube (6). Sometimes this tube is called an Emulsion Tube. Here, the fuel is mixed with air that enters the inside of the Tube through a series of small holes. The air is supplied by the Main Well Bleed (7) at the top of the Main Well. The air/fuel mixture exits from the top of the Main Well into a passage that leads it to discharge into the Booster Venturi (2) at the Nozzle (3).
The fuel flow rate in the Main System is proportional to the air flow rate; as air flow increases - from either an increase in throttle opening or an increase in engine speed at the same throttle opening - the fuel flow also increases by nearly the same degree.
At higher engine loads, such as in a heavy part-throttle acceleration, there is a need for a
richer mixture. This enrichment is provided by the Metering Rod and Step-Up Function (Figure 4). A vacuum passage (8) communicates the manifold vacuum to the underside of the Step-Up Piston (9). This vacuum tries to hold the Piston in the bottom of its bore by working against the force of the Step-Up Spring (10).
When the manifold vacuum is high, indicating a low load such as idle, cruise, or light
acceleration, it is able to overcome the force of the Step-Up Spring and hold the Step-Up Piston at the bottom of its bore, which also positions the Metering Rod at the bottom of its travel. At this point, the Rod has a large diameter that creates a high restriction through the Jet and the fairly lean A/F Ratio that is desirable for low load/low power operation. This portion of the Metering Rod is referred to as the "Lean Step" of the Rod.
When the manifold vacuum is low, indicating a high load such as a heavy part-throttle (or WOT) acceleration, the Step-Up Spring is able to force the Piston to the top of its bore and position the Metering Rod at the top of its travel. This action is called "Power Mode Staging". The portion of the rod now located in the jet has a smaller diameter, thus the restriction through the Jet is reduced and a rich A/F Ratio is provided for high load/high power operating conditions. This is the "Rich Step" of the Rod.
06-23-2006, 04:37 PM
#9
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RE: edlebrock carb
ORIGINAL: laserred9550
there is no spacer gasket on there, but i did put a length of heater hose over the fuel line to try to insulate it. Ill get the heat insulator for the carb on it. Thanx alot!!
there is no spacer gasket on there, but i did put a length of heater hose over the fuel line to try to insulate it. Ill get the heat insulator for the carb on it. Thanx alot!!
It *may* be something other than needing a insulating spacer/gasket. It *could* have need/seat/metering rod/float issues too. Try the gasket first.