Fuel pump is bad and needs replacement. We can replace with original 3-port in original mounting location or update and relocate to the frunk? What are your opinions?
'72 with non-original engine. 1.7 upgraded with larger displacement cylinders, original fuel injection.
Full Version: Fuel pump
3 port pumps are hard to find, expensive to rebuild now a days...
most people will replace with a 2 port pump because they are available and relatively cheap
2 port + 100$ or less
3 port + 400$ or more
the relocation to the front (done by the factory in 1975) helps reduce the chance of vapor lock. but were you experiencing vapor lock in the past during hot days?
the big bore cylinders mean you might also need 2.0 injectors to move more fuel.
or increased fuel pressure.... but you need to use an AFR wide band to tell and to adjust your MPS for the the new displacement.
not adjusting means running lean and increased wear or damage to your new motor.
most people will replace with a 2 port pump because they are available and relatively cheap
2 port + 100$ or less
3 port + 400$ or more
the relocation to the front (done by the factory in 1975) helps reduce the chance of vapor lock. but were you experiencing vapor lock in the past during hot days?
the big bore cylinders mean you might also need 2.0 injectors to move more fuel.
or increased fuel pressure.... but you need to use an AFR wide band to tell and to adjust your MPS for the the new displacement.
not adjusting means running lean and increased wear or damage to your new motor.
Move to the front.
Replace with a 2 port pump. They make the routing of the fuel lines so much easier!
Zach
Replace with a 2 port pump. They make the routing of the fuel lines so much easier!
Zach
2 port in the front
QUOTE(brant @ Aug 8 2023, 12:54 PM) 
3 port pumps are hard to find, expensive to rebuild now a days...
most people will replace with a 2 port pump because they are available and relatively cheap
2 port + 100$ or less
3 port + 400$ or more
the relocation to the front (done by the factory in 1975) helps reduce the chance of vapor lock. but were you experiencing vapor lock in the past during hot days?
the big bore cylinders mean you might also need 2.0 injectors to move more fuel.
or increased fuel pressure.... but you need to use an AFR wide band to tell and to adjust your MPS for the the new displacement.
not adjusting means running lean and increased wear or damage to your new motor.
There was one incident when I might have had the occurrence of vapor lock. Stalled and had trouble restarting but waiting a while and it started. That was before engine work.
I can't speak to the injectors right now. Lets assume the mechanic that did the engine work knew what he was doing and changed at that time. I will review parts to verify.
QUOTE
not adjusting means running lean and increased wear or damage to your new motor.
I've heard this before. But, why does running lean lead to increased wear or damage?
Air cooled motors are much less heat consistent than a water cooled motor
This is the reason they have to run lower compressions than a water cooled motor
Lean will increase heat and also increase pre detonation
IE : a hole in your piston and higher operating temperatures
The fuel mixture is responsible for a portion of your head cooling
Air cooled motors like to run rich and hate to run lean
This is the reason they have to run lower compressions than a water cooled motor
Lean will increase heat and also increase pre detonation
IE : a hole in your piston and higher operating temperatures
The fuel mixture is responsible for a portion of your head cooling
Air cooled motors like to run rich and hate to run lean
QUOTE(Dustin @ Aug 9 2023, 06:49 AM)
QUOTE
not adjusting means running lean and increased wear or damage to your new motor.
I've heard this before. But, why does running lean lead to increased wear or damage?
Lean condition will make the car run poorly ,but the worst problem is overheating and resulting high oil temps ,this also leads to cylinder head failure ,burnt /broken exhaust valves and valve seats that come loose .
Engine oil will become too thin and not provide sufficient lubrication to bearing ,
IMO probably the worst thing to happen to an aircooled engine .
Agreed
The worse thing you can do to it
The worse thing you can do to it
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