Installing a Mechanical Fuel Pump
Let’s face it. Some things require no explanation and, well, some things need a lot of explanation. What I find often is that I look at a product we sell here at Speedway Motors and think "I wonder how that all works", while other products I pretty much dismiss the need to have any conversation about it. That’s not always the right way of thinking. For instance, our Speedway Motors Small Block Fuel Pump looks like one of those products that would require zero explanation. However, we get a lot of calls about it.
At first glance, this is one of the products I would see and think "does this really need a set of instructions?" The more I studied the product and the more questions I received about it made me think there has to be a reason for this to be talked about here. As I opened the box, I noticed something odd about it, and that made me even more certain that this is a product that could use some explanation. So here we go...
Right out of the box, I realized something kind of strange. To me, the IN and OUT were 180 degrees off from what I would normally see of a common day fuel pump. I am not sure if this is so that people actually clock this thing exactly where they need it or maybe this is how a lot of people do it, and it's fine for some out of the box. I see the 10 bolts, 10-32 thread pitch, on the outside that require a 5/16” wrench to remove. I removed all the bolts.
Once I removed the 10 bolts, I was waiting for a bunch of springs and parts to come shooting out. This was mostly because that seems to be my luck most times! However, this is not one of those products. If you simply remove those bolts, the whole pump body comes off. No springs, no extra parts, and no real stress about uninstalling the body.
With the body removed you will see there is a diaphragm and a spring attached under the diaphragm. The only thing bad about taking the body off is that the spring wants to twist a bit and the diaphragm goes with it. When you clock the body where you want put a couple of the bolts back in it, of course making sure not to tear the diaphragm. Then set it up to the engine and see how you like the orientation of the IN and OUT. The IN side is clearly marked for you.
Once you have it clocked where you like it you can finish installing the rest of the bolts and torque them to 34.9 IN LBS. When you have everything torqued down you can think about the fittings you want to install in the 3/8 NPT IN/OUT ports. We offer a few fittings for AN6 and AN8 lines. If you would like to do 3/8 rubber line with line clamps then we offer these 3/8 NPT Male to 3/8 Inch Hose Barb Adapters.
Make sure you have removed the old fuel pump gasket from the block and checked the fuel pump pushrod for wear. Believe it or not, if you have a used engine or one that has seen wear, then you want to replace it at this time. I like to see some grease added to the rocker arm on the fuel pump and some into the rocker arm cavity to lubricate the internal parts.
When that is complete, place the new mounting gasket onto the surface of the pump, holding it in place while starting the bolts through the pump flange and gasket. After the bolts have started into the engine block, tilt the pump either toward or away from the block to correctly place the lever against the cam.
One thing to note is that on pushrod driven pumps, you must make sure the pump lever is mounted under the pushrod at low cam. When the pump is positioned properly, the pump should squawk with each movement. This is how you will know everything is installed correctly. Some people use different things to hold the pushrod up, like a hacksaw blade or something equivalent. Tighten down each bolt equally alternating from side to side.
Make sure all fittings, hoses, and clamps are tight and you have no leaks. I know some people don’t believe in fuel pressure regulators, but I sure do. I like to see a nice regulator installed like Speedway's Chrome Adjustable Fuel Pressure Regulator and set for the carburetor you are using. Following these instructions, I think you can have a good, clean install without any leaks or hassles. Happy Hot Rodding!
