VMacKenzie
Member
- Joined
- Dec 9, 2007
- Messages
- 625
The p-pump is the bomb when it comes to serious fueling but its fixed timing is its greatest drawback. Seriously advancing the timing creates hard starting and reduced efficiency at lower RPM, doesn't make for much of a daily driver.
I would think if someone really wanted to do it they could build a timing gear with built-in centrifugal advance. As RPM rises it pushes the pump ahead of the crank position. It wouldn't take a bunch of mechanical movement, since each degree of pump advance gives you 2 degrees of timing advance you would only need about 8 degrees total (to give you 16 degrees total advance). Let's say your base timing is set to 12 degrees (the amount of timing you'd have at 1000 RPM), and let's say full advance happens at 4000 RPM (ie if you rev higher you don't get any higher timing). That means at 4000 RPM you would have 12+16 =28 degrees of timing. It would follow a curve, so at 2000 RPM you'd have about 12+5= 17 degrees, 3000 RPM it's at 12+11=23 degrees and so on. I'm just using this as an example, how it's ultimately "set up" will determine what sort of advance curve and total amount of advance it will have.
So what would it take to build such a piece? First and foremost it takes a ton of horsepower to drive a competition p-pump, maybe more than 100 HP. . .any centrifugal mechanism that tries to drive the pump forward will tend to get driven back during hard fueling. It would require some fairly heavy weights and springs to counteract this. If the advance weights can travel at least 1-2 inches, and weigh enough, it should give enough "gearing" to force the pump forward and help prevent drag-induced timing retard.
If such a gear could be built it's doubtful it would fit inside the existing cover. . . but if such a beast were to be built no one would mind paying a few extra bucks for a custom cover with removable plate so they could swap out springs and tune their timing curve
Anyway just thought I'd speculate a bit and see where the discussion goes and find out if anyone has looked into pursuing such a project. Imagine having crazy competition timing yet be able to start it like a stocker, and get the turbos to spool so much better. There would be a long line for this if it became a reality.
I would think if someone really wanted to do it they could build a timing gear with built-in centrifugal advance. As RPM rises it pushes the pump ahead of the crank position. It wouldn't take a bunch of mechanical movement, since each degree of pump advance gives you 2 degrees of timing advance you would only need about 8 degrees total (to give you 16 degrees total advance). Let's say your base timing is set to 12 degrees (the amount of timing you'd have at 1000 RPM), and let's say full advance happens at 4000 RPM (ie if you rev higher you don't get any higher timing). That means at 4000 RPM you would have 12+16 =28 degrees of timing. It would follow a curve, so at 2000 RPM you'd have about 12+5= 17 degrees, 3000 RPM it's at 12+11=23 degrees and so on. I'm just using this as an example, how it's ultimately "set up" will determine what sort of advance curve and total amount of advance it will have.
So what would it take to build such a piece? First and foremost it takes a ton of horsepower to drive a competition p-pump, maybe more than 100 HP. . .any centrifugal mechanism that tries to drive the pump forward will tend to get driven back during hard fueling. It would require some fairly heavy weights and springs to counteract this. If the advance weights can travel at least 1-2 inches, and weigh enough, it should give enough "gearing" to force the pump forward and help prevent drag-induced timing retard.
If such a gear could be built it's doubtful it would fit inside the existing cover. . . but if such a beast were to be built no one would mind paying a few extra bucks for a custom cover with removable plate so they could swap out springs and tune their timing curve
Anyway just thought I'd speculate a bit and see where the discussion goes and find out if anyone has looked into pursuing such a project. Imagine having crazy competition timing yet be able to start it like a stocker, and get the turbos to spool so much better. There would be a long line for this if it became a reality.
