Tell me more about the early FJ pressurized fuel system.....

Does a delivery pressure of 14.7 psi at the carbies sound familiar?

Noel

I’m familiar with that number as air pressure at sea level, but not for fuel “delivery pressure” in a FJ gravity flow system......you sure you got that right Noel......or are you are just trolling?

A 33ft column of water is one atm, or 14.7 psi, one foot height of water generates a pressure of 14.7/33, or 0.44 psi pressure. Gasoline @ .75 the density of water, then at a height of 1 foot above the carb (full tank) would genertate a maximum pressure (not accounting for system flow resistance**) of (0.44)(0.75), or 0.33 psi at the carb inlet. If you reduced that distance down to 4” assuming 1/4 tank fuel level, it would then be less pressure (0.44)(0.33)(0.75) or 0.10 psi

Is this the fuel delivery pressure you are referring to? 1/10th of a pound per square inch?

Wow, that’s not very much, huh?

*** Factor in system flow resistance and it wouldn’t take much to impede that flow would it? (Hint)

So, now that we understand about fuel line pressure (at sea level) let’s reduce that pressure to account for elevation....say at 5,000 ft what would be the atmospheric pressure? (12.2 psi) so that means the fuel line pressure would be further reduced by 12%

So now our fuel line pressure with 1/4 tank at 5,000’ is only 0.09 of a pound per sq.inch.

It’s funny Pat, on a number of occasions you’ve sought to publicly ridicule me by saying I don’t understand how gravity works, specifically in the context of fuel flow, even though you know that to be untrue and knowing full well it’s my trade....

Ok, Noel, you’re a smart guy being in the trade and all....please help me with your answers to the following:

Now that the fuel line pressure is understood (correct?) let’s talk about fuel flow...specifically:

Using the above fuel line pressures, (0.09 psi)

1) What’s the fuel flow of a 1/4” ID fuel line 12” long?

2) What’s the fuel flow of a 10mm ID fuel line 12” long?

Now let’s see what the carbs need to feed our FJ engines.

Using a air/fuel ratio of 12 to 1 with a 1200cc FJ air pump spinning at 9,000 rpm with a 120hp power output (WFO) what is the flow needed to each carb, and the total flow needed from the single fuel line leaving the petcock?

At sea level? At altitude? (5000 MSL)

Don’t help guys....let’s see what Noel comes up with, after all, he opened the door.

....or maybe he was just trolling after all.