I have a 1920 Holley that has the accelerator pump with THE FLAT notched bar connected to the diaphragm (instead of the ROUND bar and the smaller spring).
My question is this; I know the round bar type has a spring on both side of the diaphragm, but is the FLAT BAR type suppose to have a spring on BOTH SIDES of the diaphragm.
The flat stem pump uses a spring between the pump diaphragm and the economizer body (some call this the metering block).
What might cause my carburetor to flood?
Fuel pump pressure too high - test and compare with your motors manual. New pumps are especially suspect. Check your motors manual for the correct pressure, otherwise look for 4.0 to 4.5 lbs.
Needle & seat has dirt in seat. Your gas tank may be dirty. It is not uncommon to have dirt rush up and get into the carburetor after a rebuild. Sometimes blowing air into the fuel inlet will clean it out.
Fuel pump pressure too high - test and compare with your motors manual. New pumps are especially suspect. Check your motors manual for the correct pressure, otherwise look for 4.0 to 4.5 lbs.
Needle & seat has dirt in seat. Your gas tank may be dirty. It is not uncommon to have dirt rush up and get into the carburetor after a rebuild. Sometimes blowing air into the fuel inlet will clean it out.
The needle may have been damaged while adjusting the float. Any pressure on the needle can damage it and cause it to leak.
Leaking fuel past the seat. Be sure that if a gasket is used that it is there. Also make sure the old gasket is completely off.
Economizer diaphragm may be bad, or the vacuum passage is plugged. At idle vacuum pulls the diaphragm up. At higher speeds the diaphragm goes down and pushed down on the power valve. Make sure the power valve isn't sticking.
Float level is off. Turn the carburetor upside down and set the float to be level.
Float is bad. Weigh the float for correct weight. Economizer assembly
Leaking fuel past the seat. Be sure that if a gasket is used that it is there. Also make sure the old gasket is completely off.
Economizer diaphragm may be bad, or the vacuum passage is plugged. At idle vacuum pulls the diaphragm up. At higher speeds the diaphragm goes down and pushed down on the power valve. Make sure the power valve isn't sticking.
Float level is off. Turn the carburetor upside down and set the float to be level.
Float is bad. Weigh the float for correct weight. Economizer assembly
I have a rebuild kit for a 1920 Holley carburetor number k458 85 - 114. It comes with a small ball that looks like a ball bearing and I believe this is supposed to go into my economizer assembly. However it seems a little bit too small as a just sinks down to the bottom of the well and is not held up by the spring. I've attached a photo to help illustrate this. The ball bearing that is seated in there currently was in my carburetor originally. I did not see another metal ball come out of the assembly when I took it apart although I did see the brass piece that holds the spring in the well. So I am assuming that the metal ball that was in my rebuild kit is supposed to go into that shaft.I'd appreciate any help you can give me with this. Do I have the right kit?
This one is supposed to have an additional check ball and retainer on top of the spring, same as the other side. As far as I know, the ball and spring are not included in the kit.
Floods When I Turn the Engine Off
Check here for correct float weights. Make sure the float isn't rubbing on the side.
After running my vehicle and I turn it off, gas floods over into the intake flooding the engine. Won't start.
Make sure the float isn't rubbing on the side.
After running my vehicle and I turn it off, gas floods over into the intake flooding the engine. Won't start.
After running my vehicle and I turn it off, gas floods over into the intake flooding the engine. Won't start.
- Could be fuel pressure - When the engine if shut off there should be some release of pressure. Make sure you have a vented gas tank. After running open the gas cap. Do you get a rush of air? If so, then you need to vent your gas tank. Some vent through the gas cap itself and some have a separate tube coming up from the gas tank. Make sure the tube is clear. Test your fuel pressure. Should be about 4 lbs or less, but compare with what your motor manual says.
- Your gas may be percolating - The engine gets hot, you turn it off and the gas boils over, or evaporates out of the carburetor. Gas has a lower boiling point these days and especially in hot parts of the year, this may be a challenge. Experiment with different brands of gas. Try Ethanol Defense ethanol additive in the gas. Make sure fuel lines are away from the manifold. Is your water running at a good temperature. While very hard to find, spacers will sometime help. Do you have a bowl vent on top of the carburetor and is it hooked up to a hose correctly? Check the bowl vent gap. Specifications are in the carburetor kit instruction sheet.
Idle Compensator
Make sure the float isn't rubbing on the side.
After running my vehicle and I turn it off, gas floods over into the intake flooding the engine. Won't start.
- Could be fuel pressure - When the engine if shut off there should be some release of pressure. Make sure you have a vented gas tank. After running open the gas cap. Do you get a rush of air? If so, then you need to vent your gas tank. Some vent through the gas cap itself and some have a separate tube coming up from the gas tank. Make sure the tube is clear. Test your fuel pressure. Should be about 4 lbs or less, but compare with what your motor manual says.
- Make sure the float isn't rubbing on the side.
After running my vehicle and I turn it off, gas floods over into the intake flooding the engine. Won't start.- Could be fuel pressure - When the engine if shut off there should be some release of pressure. Make sure you have a vented gas tank. After running open the gas cap. Do you get a rush of air? If so, then you need to vent your gas tank. Some vent through the gas cap itself and some have a separate tube coming up from the gas tank. Make sure the tube is clear. Test your fuel pressure. Should be about 4 lbs or less, but compare with what your motor manual says. Some Holley 1920 carburetors have a hot idle compensator. The compensator opens a vent into the main body letting off some pressure when coming to an idle. If the idle compensator is bad the idle will be erratic. To test:
- Remove the air cleaner with engine running.
- Cover the hot idle port. If the idle smooths out there is something wrong with the idle compensator. Check the seal and/or replace.
Runs Rough When Cold- Make sure the ignition system is up to par. Too many problems are blamed on a bad carburetor when in fact it is the ignition.
- Is the choke valve closed when cold?
- A small vacuum leak can make an engine run rough, then when the engine is heated up, the vacuum leak seals itself. When cold spray carburetor clean around the mounting gasket, intake manifold and any vacuum hose connection.
Gas Is Coming Over the Top, or Out Of The Throttle Shaft.The carburetor is flooding.Leaking out of the throttle shaft ends means the gas is flooding down the bore and then hits the throttle valve, running out the shaft.
- Make sure the float isn't rubbing on the side.
