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MFI Recalibration with a cam swap?
If one swaps out "S" cams and replaces with "E", does the "S" MFI pump need to be recallibrated, or get a new space-cam?
Thanks for they help!
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1973 Coupe Projekt X (AKA bunch o' boxes full of parts) |
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06-30-2011, 07:49 PM
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Max Sluiter
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Yes, the air/fuel ratio will be off at points- which means too rich and less power as well as too lean in some areas, and more severe engine damage.
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1971 911S, 2.7RS spec MFI engine, suspension mods, lightened Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance |
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06-30-2011, 08:17 PM
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Thanks Flieger. This is a basic air/fuel adjustment, and not a Gus Pfister adjustment, right?
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1973 Coupe Projekt X (AKA bunch o' boxes full of parts) |
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06-30-2011, 08:22 PM
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Max Sluiter
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With a proper air/fuel ratio sensor like an LM-1 or Wego, you should be able to tune the pump with the mid and high speed screws to get the mixture correct most of the time. At least you will be able to eliminate any lean spots in the midrange where the E cams will flow more air than the S cam would. The top end will be rich but you should not need to go too far up there if your gear ratios are close enough together. The engine will "fall on its face" quicker than an E space cam would, not to say it will be like hitting a brick wall, just a more abrupt loss of power after the peak.
That said, worn throttle bodies could make this difficult. Anyway, you should be able to get by with an E space cam.
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1971 911S, 2.7RS spec MFI engine, suspension mods, lightened Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance |
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06-30-2011, 08:30 PM
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Location: France
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Kugelfischer
Flieger is right, the space cams are slightly different ... you may use a LM1 analyzer to tune your AFR ... or it will be rather hazardous, but if you don't mind about fuel consumption, you may start to turn the main rack counter clockwise to richen the all range, and see what happens, otherwise white screws on regulator : high speed black screws : mid range notice that if you turn these screws to much, you may be in a leaner area, this is the other size of the hill (on the space cam)Philippe
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www.injectionsystemes.fr Last edited by philippeF; 07-01-2011 at 12:43 AM.. |
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07-01-2011, 12:28 AM
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Swap them with Solex cams, should make it a little easier to tune and you will be happier then with an E cam. You can also adjust the rod from the pump to the rack, but that is a last resort. Like stated, a wide band is the way to go. Slap them in and if you can't get it right, send to Gus.
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72 911 Although it is done at the moment, it will never be finished. |
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07-01-2011, 04:31 AM
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Quote:
MFI Pump - Open Heart Surgery
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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07-01-2011, 05:14 AM
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Good read, thanks.
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1973 Coupe Projekt X (AKA bunch o' boxes full of parts) |
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07-01-2011, 03:31 PM
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1971 Porsche 911S
Tobluforu
