DCOE: Fuel Lines
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The level in the float bowl varies with fuel pressure as the float needs a higher level to close off the valve against more pressure. A more constant fuel pressure and thus fuel level achieves a more constant air fuel ratio within the limits achievable by the carb tuning.
With the fuel pump / regulator in the boot the approx +/- 1 to 1.5 psi variation you will see at the carbs due to car acceleration and braking is not insignificant especially if sustained for any period and not just a brief transient
cheers
Rohan
With the fuel pump / regulator in the boot the approx +/- 1 to 1.5 psi variation you will see at the carbs due to car acceleration and braking is not insignificant especially if sustained for any period and not just a brief transient
cheers
Rohan
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rgh0 - Coveted Fifth Gear
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TBG wrote:Can someone please elucidate why one needs a pressure regulator at all. I don't have one and at over 200k have never needed one - or have I? I am confused of West camel!! D
Those old Ford engineers were pretty smart. The original engine mounted fuel pump delivers fuel at a regulated pressure right underneath the carbs and avoids the problems discussed in this thread. So, for 200k miles, that little return spring in the pump has been regulating your fuel pressure without you even realising it.
The problems come when you put a pump in the boot, and charge around in the car like Rohan. If you want to go down that route, mounting a pressure regulator near the carbs is an effective solution.
68 Elan S3 HSCC Roadsports spec
71 Elan Sprint (still being restored)
32 Standard 12
Various modern stuff
71 Elan Sprint (still being restored)
32 Standard 12
Various modern stuff
- Andy8421
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nmauduit wrote:what I meant is as long as the pressure does not go down to 0 for some time (to be defined) there should always be the proper fuel level in a well operating carb (i.e. you may set your warning to 1psi if it gets annoying)
That's a reasonable suggestion. I think I'll do that. It hasn't been on my agenda as many other tweaks are underway.....
Graeme
S4 SE
S2 GTS
Caterham 420R
Sold - Peterson JPS Exige
S4 SE
S2 GTS
Caterham 420R
Sold - Peterson JPS Exige
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661 - Coveted Fifth Gear
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If you want an interesting carburettor design to study have a look at the one used on your typical brush cutter. No fuel pump required, operates in any position and not affected by g-forces! The design is derived from carburettors developed for aircraft.
1970 Ford Escort Twin Cam
1972 Ford Escort GT1600 Twin Cam
1980 Ford Escort 2.0 Ghia
Peugeot 505 GTI Wagons (5spdx1) (Autox1)
2022 Ford Fiesta ST.
1972 Ford Escort GT1600 Twin Cam
1980 Ford Escort 2.0 Ghia
Peugeot 505 GTI Wagons (5spdx1) (Autox1)
2022 Ford Fiesta ST.
- 2cams70
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Lots of good information here.
I always go for keep it simple and safe on a racecar.
Use a AN bulkhead fitting on the firewall.
Short hose to a AN bulkhead T fitting bracketed to the top of the footwell.
Two hoses from the T to each DCOE from under.
Use AN to metric fittings on the DCOEs.
I think the tube type 90 degree AN fittings are just more elegant.
Put the pressure regulator and filter (if used) in the cabin or trunk to keep the engine bay neat and tidy.
I always go for keep it simple and safe on a racecar.
Use a AN bulkhead fitting on the firewall.
Short hose to a AN bulkhead T fitting bracketed to the top of the footwell.
Two hoses from the T to each DCOE from under.
Use AN to metric fittings on the DCOEs.
I think the tube type 90 degree AN fittings are just more elegant.
Put the pressure regulator and filter (if used) in the cabin or trunk to keep the engine bay neat and tidy.
- lance54
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Personally I think it best to not have any junctions within the cabin, or indeed the bulkhead. Maybe over cautious, but there you have it. I think the bulkhead fittings look quite neat , though
Graeme
S4 SE
S2 GTS
Caterham 420R
Sold - Peterson JPS Exige
S4 SE
S2 GTS
Caterham 420R
Sold - Peterson JPS Exige
-
661 - Coveted Fifth Gear
- Posts: 1330
- Joined: 29 Mar 2012
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