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Join Date: Feb 2000
Location: Dallas, TX
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Rebuild question- MFI or Webers for break-in?

Hello,

I will be posting more questions later about my 2.4S rebuild, but I wanted an opinion on which direction I should take with regards to fuel systems and breaking in the engine.

My car was running on Webers when some head studs decided they wanted to pull out of the case. I had been planning on switching over to a Euro MFI setup that I had purchased several years ago, but I have never gotten around to installing it. So my question is, when it comes time to breaking-in my engine, should I start with the Webers since they work, or try to get the MFI setup from the beginning?

I have read that you want the car started quickly for the initial start instead of cranking over and over, so I am tempted to run the Webers for the first 1,00 miles and then switch over.

The MFI is an unknown quantity. I did purchase new injectors since the previous ones were supposedly marginal. Can I get the MFI pump tested to see if it works, or do I need to send it to Gus for an overhaul that may or may not be necessary?

Thanks for the advice.

Neil

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Neil
'73 911S targa
Old 09-21-2010, 12:48 PM
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I would think that if you re-built the motor to the same specs as before the tear-down, that the Webers are a no-brainer. Trying to get the MFI set-up while trying to get the timing and initial break-in done seems to be adding layers of uncertainty that is unnecessary. The process I like for break-in is to go out and drive the car pretty hard to get the rings to seat well. If the MFI is not set up properly that won't be possible.

Lindy
Old 09-21-2010, 01:06 PM
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definitely start and initial break-in/tune on webers. I'll be starting my 2.4E engine on webers then changing to mfi afterward. too many variables with an unknown mfi system to use at start up, if you have the webers as an option. contact 356RS ( Mark Jung) here on pelican for MFI work. he can check, flow test, and rebuild your pump if necessary.
Old 09-21-2010, 01:09 PM
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Join Date: Jul 2001
Location: mt. vernon Wa. USA
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Start on Webers

Here is my easy 3-step break in progression. 71 2.2E

1: Carbs. 1st fire up on the test stand + break in eventually
YouTube - 71E engine start1
2: MFI.....1st fire up on the test stand. Allowed me to dial in the MFI
YouTube - mfistart 001
3: MFI...in the 71E
YouTube - Porsche 71E resto, there is fire

Regards,

al

PS: Mark Jung did some rebuilding of and calibrated my pump. He knows his stuff. Highly reccomended.

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Old 09-21-2010, 06:38 PM
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