MY VEHICLE HAS A STUMBLE FROM A DEAD STOP. WHAT CAN I DO TO CURE THIS?
The most common cause of a stumble is not having an adequate accelerator pump shot. The first thing to do is to look at the discharge nozzle and make sure you are getting a good strong pump shot. If not then you need to inspect the pump diaphragm for a hole or tear. You will also need to make sure that the pump passage is clear from any trash or debris. First, you will need to check the adjustment on the pump. To do this you will open the throttle all the way (WOT). Push the pump arm lever down and then adjust the pump override spring to obtain .015" clearance between the pump arm and lever. If you are having a stumble and no black smoke out the tailpipe then you will need to increase the shooter size. If it stumbles and you are getting black smoke from the tailpipe then it will be necessary to decrease the shooter size.
HOW DO I ADJUST THE FUEL LEVEL ON MY CARBURETOR?
Setting the fuel level should be the first thing you do before attempting to make any further adjustments. The float level should put the fuel level just below the bottom of the sight plug hole. You will make the adjustment with the vehicle on a level surface and the engine idling. You will first remove the sight plug, then to make your adjustment you will need to loosen the lock screw on the needle and seat. This will allow you to turn the adjusting nut to raise or lower the float level. Each hex flat on the nut will change the float level approximately 1/32". When you have the fuel level just below sight plug hole you will then tighten the lock screw and reinstall the sight hole plug. Make sure you have a shop towel handy in case you have any fuel leaks from the Sight plug or needle and seat adjusting nut.
I CAN REV THE ENGINE WHEN IT IS IN PARK AND THE SECONDARIES WILL NOT OPEN. WHY IS THIS?
The secondaries will not open by free revving the engine. The engine needs to be under a load before they will open. If you are still uncertain if they are opening or not you can take a normal paperclip and clip it onto the secondary diaphragm rod. You will then push it up against the bottom of the secondary diaphragm housing, now you will need to go out and drive the vehicle. When you return you will be able to look at the position of the paperclip on the rod. If it is lower on the rod then you can tell the secondaries opened and how far they opened. This is useful in determining if you need a heavier or lighter secondary spring.
HOW DO I FIND THE "LIST" NUMBER ON MY CARBURETOR?
The list number for most performance and factory 2 and 4 barrel carburetors will be found stamped into the upper right-hand corner of the airhorn or sometimes called the choke tower. On the 4150 HP models that do not have a choke tower, the list number will be stamped into the main body behind the throttle linkage. This number is used to identify the carburetor and also used when needing service parts or renew kits.
AFTER I SHUT MY CAR OFF AND COME BACK OUT THE NEXT MORNING THERE IS GAS ON THE THROTTLE SHAFT AND PUDDLED ON THE INTAKE. WHAT CAUSES THIS?
This is usually caused by percolation. This is when the engine is shut off and the engine temperature rises it causes the fuel to boil in the bowl and leak out of the boosters. There are a couple of things you can do to cure this one is make sure the fuel level is not too high. You can also lower the fuel level about 1/8" below the sight plug hole and this will cure it sometimes. The heat from the engine will rise into the carburetor sometimes and will cause the fuel to boil. Installing a phenolic heat spacer between the carburetor and the intake or a heat shield can cure this. These parts will prevent heat from getting to the carburetor and boiling the fuel.
I HAVE A VACUUM SECONDARY CARBURETOR THAT BOGS WHEN THE SECONDARIES COME IN. WHAT WILL CAUSE THIS?
Bogging and hesitation are caused by the secondaries coming in too quickly. You can install a heavier secondary spring and this will prevent the secondary from coming in too soon. If the engine is sluggish in response at full throttle then the secondaries may not be opening soon enough. You will then need to go to a lighter spring. The spring kit is part number 20-13 which will have 7 different springs to fine-tune with.
HOW DO I KNOW IF A VACUUM OR MECHANICAL CARBURETOR IS BEST FOR ME?
For street cars the vacuum secondary carburetor works best on midweight or heavyweight cars with an automatic transmission. They are more forgiving than a Double Pumper is because they work by sensing engine load. The mechanical secondary carburetor is best on a lighter car with radical camshaft and a lower gear and manual transmission or on a car that is going to be used for racing purposes.
I JUST BOUGHT A NEW CARBURETOR AND IT HAS A WARNING THAT IT WILL NOT WORK WITH AN AUTOMATIC OVERDRIVE TRANSMISSION. WHAT CAN I DO ABOUT THIS?
This warning was placed with the carburetor because if not installed properly with the correct transmission kick down bracket for the GM 700R4 it will result in premature transmission failure.
I WANT TO RUN A CARB SPACER WITH YOUR INTAKE. WHAT IS BETTER OPEN CENTER OR FOUR HOLE?
Results will vary from application to application. However, on average a four-hole spacer will emphasize low to mid throttle response open center will accentuate the top end. The phenolic spacer will help reduce the chances of percolation.
WHAT TORQUE SPECIFICATION SHOULD MY NEW INTAKE MANIFOLD BOLTS BE INSTALLED AT?
Follow the torque specification as outlined in your instruction manual following the factory sequence unless otherwise specified.
THE DISTRIBUTOR HOLE ON MY NEW INTAKE IS LARGER THAN STOCK. IS THIS NORMAL?
Yes. Most performance aftermarket intakes utilize a larger than stock distributor hole. The distributor is centered by the block, not by the intake
MY NEW BIG BLOCK CHEVY INTAKE DOES NOT HAVE BOLT HOLES BETWEEN THE PORTS. IS THIS OK?
Yes, due to the large port configuration of many performance intakes the upper bolts can not be utilized Felpro offers the appropriate gaskets for this application.
SHOULD I USE THE RUBBER OR CORK SEALS UNDER THE FRONT AND REAR OF THE INTAKE?
Unless otherwise specified in the intake manifold installation instructions you should use a high-quality RTV such as Permatex ultra black to seal the front and rear of the intake.
MY INTAKE MANIFOLD DOES NOT SIT LOW ENOUGH IN THE INTAKE VALLEY TO INSTALL THE BOLTS WHY?
At some point, either your heads and or block were surface milled resulting in a narrower intake valley. Your intake will need to be machined accordingly to compensate for the variances associated with this situation.
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For company Information and to learn about Holley®, please visit the About Page.
WHAT IS YOUR WARRANTY?
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