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Old 05-04-2011, 09:09 AM   #1
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MC2100 jet / power valve questions

Ok so I posted a question on the MC2100 yesterday and have spent all of yesterday and today looking up old posts and have a better understanding on the MC2100. But still could use some clarification from you guys. Basically my problem is my 89 YJ has a little dip in performance between 1500 - 2200 RPMs. Nothing major, but noticeable in fact I didn't notice it until I ran with the choke 3/4 of the way closed. When I did this I noticed better power out of it. This would mean too lean. Correct?

What I think I found out is that the idle mixture screws just adjust the fuel mixture at idle. (duh, but I didn't realize this till I researched) Then the jets take over in the mid-high range to provide fuel until the power valve kicks in higher up in the RPMs. Is this an accurate picture for how they all work? If so my problem with the lean mixture in the mid range would be too small of jets in my carb. Also when I rebuilt my carb I might not have measured the float level correctly, why does the float need to be at a specific level?

On a side note where do I take my vacuum readings for lets say my inches hg to get the proper power valve size, or to set the idle mixture screws correctly?

Any input to help clear thing up would be much appreciated.

Thanks

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Old 05-04-2011, 10:12 AM   #2
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Start here. Its says its for a 2150 but there is very little difference. This will apply to the 2100. Click the link at the bottom of the page to continue.

Motorcraft 2150 2V Theory and operation

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Old 05-05-2011, 10:39 AM   #3
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Thanks for the info. I will hopefully take a look at the carb it this weekend and see how everything looks. Hopefully I can get a bit more gas into it to smooth out the flat spot.

I adjusted the timing from 8* BTDC to 11* BTDC yesterday. It runs a little better. Anyone think that might bee too much advance?
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Old 05-05-2011, 11:24 AM   #4
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mine runs good at 12, but i run at 10,,mine had stumble- it was trash in the idle needle. try putting the rod on the top hole-it will shoot more gas sooner
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Old 05-05-2011, 02:14 PM   #5
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Quote:
Originally Posted by rambo3489 View Post
I adjusted the timing from 8* BTDC to 11* BTDC yesterday. It runs a little better. Anyone think that might bee too much advance?
Okay as long as it doesn't ping.
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Old 10-18-2011, 09:21 PM   #6
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any luck with this seems a similar problem to what I'm having

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