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Unread 06-23-2011, 08:16 AM   #1
jhumphrey
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Post-MC2150 swap: to Nutter or not?

Hey all,

I performed the MC2150 carb swap last weekend. Everything went on flawlessly, I didn't have to adjust anything. Per the instructions (I bought it from the ebay guy), I hooked up the system to get it running, but didnt do the Nutter bypass (it says to get it running, do the bypass AFTER you make sure it runs/idles).

Anyway, I let it warm up and drove it around the block and at highway speeds. It drives perfect. No misfire, sputter, hesitation, etc. So my question is, do I need to do the nutter at all? I subscribe to the "if it aint broke, dont fix it" philosophy. I spoke to my mechanic buddy (a real, certified, mechanic...not shade tree) and he said if its running fine to just leave it alone. Always looking for second, third, or fourth opinions, I contacted the ebay guy. He said this:

"I have run many setups w/o doing the bypass, however... I still recommend it. It will eliminate the computer and problems down the road from the equation. I say do it."

What "problems down the road" is he referring to? I have the proper wires and also have a timing light, so I can do the bypass whenever. Basically, Im looking on what the cons vs. pros are in this matter. I havent been able to see what my MPG is with the new setup (since it was just installed and the jeep is a weekend vehicle), but I have noticed that throttle response, idle, and "powerband" is much better than the Carter. Plus, no more hard starting.

Thanks everyone!

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Unread 06-23-2011, 08:22 AM   #2
vadslram
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I switched out the distributer for an HEI one but before that I ran it without nuttering and I never had a problem. Either team rush or HEI, but upgrading the ignition is definitely your next mod.
I never worry about my comp now..in fact it is safe in a box in my garage
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Unread 06-23-2011, 08:41 AM   #3
jhumphrey
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Quote:
Originally Posted by vadslram View Post
I switched out the distributer for an HEI one but before that I ran it without nuttering and I never had a problem. Either team rush or HEI, but upgrading the ignition is definitely your next mod.
I never worry about my comp now..in fact it is safe in a box in my garage
I guess I should have mentioned that: I did the team rush upgrade the weekend before I did the mc2150 swap
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Unread 06-23-2011, 08:49 AM   #4
Peter Nuss
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Well, if you changed the carb, you pretty much de-smogged it also. So now you have a computer adjusting your timing with part of the system missing. Do you really think a computer like operating with missing data?

I'd nutter it, change the distributer to an earlier one (more advance in the distributer), remove all the computer wiring etc., and not look back. Anytime I can remove a possible issue to make trouble shooting other issues later on easier, I jump on it. Certified Mechanics like trouble shooting problems, they get good money doing it. Some mechanics won't work on modified vehicles, so, you are pretty much on your own, simplified it now is what I would do. Good luck with your project.
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Unread 06-23-2011, 08:53 AM   #5
jhumphrey
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Quote:
Originally Posted by Peter Nuss View Post
Well, if you changed the carb, you pretty much de-smogged it also. So now you have a computer adjusting your timing with part of the system missing. Do you really think a computer like operating with missing data?

I'd nutter it, change the distributer to an earlier one (more advance in the distributer), remove all the computer wiring etc., and not look back. Anytime I can remove a possible issue to make trouble shooting other issues later on easier, I jump on it. Certified Mechanics like trouble shooting problems, they get good money doing it. Some mechanics won't work on modified vehicles, so, you are pretty much on your own, simplified it now is what I would do. Good luck with your project.
Thanks Peter. I wasnt sure how much the computer really did, I was also curious about why some people Nutter and some dont (and never experience any problems).
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Unread 06-23-2011, 09:03 AM   #6
Peter Nuss
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Since you have the team rush upgrade, you are most of the way there. The distributer you might get is part number 30-4691 from advance auto on line about $70 I think. It will use all your team rush parts. I always take my old distributer gear off the old distributer and put it on the new distributor. Just so I don't have a new part wearing/breaking in on my old part. I sure most people don't do this, just be sure you get it on the right way. Mark the gear on the side the rotor is pointing to and put in on the new distributor the same way.

Take you time removing the computer wires. Open the harness and remove the wires one by one from the firewall end. You engine compartment will look a lot neater when it all done. Good luck.
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Unread 06-23-2011, 09:23 AM   #7
jhumphrey
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Quote:
Originally Posted by Peter Nuss View Post
Since you have the team rush upgrade, you are most of the way there. The distributer you might get is part number 30-4691 from advance auto on line about $70 I think. It will use all your team rush parts. I always take my old distributer gear off the old distributer and put it on the new distributor. Just so I don't have a new part wearing/breaking in on my old part. I sure most people don't do this, just be sure you get it on the right way. Mark the gear on the side the rotor is pointing to and put in on the new distributor the same way.

Take you time removing the computer wires. Open the harness and remove the wires one by one from the firewall end. You engine compartment will look a lot neater when it all done. Good luck.
I followed JeepHammer's 'how-to', since he did invent it But, I didnt change the distributor or coil (he said I didnt have to). I still noticed a tremendous difference and even more so after the mc2150 swap. The only thing I didnt do was Nutter... thats why I posted this thread, Im on the fence on whether or not I should nutter now, wait and see, or not do it at all.
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Unread 06-23-2011, 10:53 AM   #8
jth0033
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I just completed my motorcraft swap and haven't done the Nutter yet. Interested to see what everyone says about it. I want to do it, but have never done timing stuff so I'm afraid to adjust it and mess something up.
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Unread 06-23-2011, 11:17 AM   #9
jhumphrey
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Quote:
Originally Posted by jth0033
I just completed my motorcraft swap and haven't done the Nutter yet. Interested to see what everyone says about it. I want to do it, but have never done timing stuff so I'm afraid to adjust it and mess something up.
That's why I posted. I'm sure I'm not the only one wondering

I've never adjusted timing either and I don't want to do something that isn't going to make a tremendous difference. "not broke, don't fix it"
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Unread 06-23-2011, 11:22 AM   #10
vadslram
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Since you did the carb and the Rush your computer really doesn't have much to do anyway.
It can't materially effect the timing, just the dwell. In Jeeps of our age the only inputs are vacume and O2. not throttle, crank, temp or anything really technical.
Put it out of it's misery and you will have one less thing to worry about.

Computers are for fuel injection and distributerless ignitions anyway.
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Unread 06-23-2011, 11:55 AM   #11
jhumphrey
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Quote:
Originally Posted by vadslram
Since you did the carb and the Rush your computer really doesn't have much to do anyway.
It can't materially effect the timing, just the dwell. In Jeeps of our age the only inputs are vacume and O2. not throttle, crank, temp or anything really technical.
Put it out of it's misery and you will have one less thing to worry about.

Computers are for fuel injection and distributerless ignitions anyway.
I've looked on here for a picture guide on how to do the nutter. The most definitive has the pictures removed for some reason. Do you know of another one?

The one on here shows you cutting wires (purple and orange) at the ICM. Another thread says to SPLICE into the purple wire. Which is correct?
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Unread 06-23-2011, 01:20 PM   #12
monkeyhouse
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Go to the FAQ's. Under engine/carb swaps there are three writeups on doing the nutter. The only reason most people do not do the nutter is because they have to pass emissions testing. The nutter bypass is a simple thing to do, people who are scared to death to work on engines do it and are happy they did. If you can swap a carb, you can definitely check timing. Go to autozone, they have a timing light there for 40 bucks. Everyone should feel comfortable checking their timing. It's easy and you will feel better knowing what it's set at. And you are cutting and splicing. You are really just cutting the computer out of the mix. Now both of you get out there and do the nutter! lol.
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Unread 06-23-2011, 02:12 PM   #13
jhumphrey
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Quote:
Originally Posted by monkeyhouse
Go to the FAQ's. Under engine/carb swaps there are three writeups on doing the nutter. The only reason most people do not do the nutter is because they have to pass emissions testing. The nutter bypass is a simple thing to do, people who are scared to death to work on engines do it and are happy they did. If you can swap a carb, you can definitely check timing. Go to autozone, they have a timing light there for 40 bucks. Everyone should feel comfortable checking their timing. It's easy and you will feel better knowing what it's set at. And you are cutting and splicing. You are really just cutting the computer out of the mix. Now both of you get out there and do the nutter! lol.
I have a timing light, 16 ga orange and purple wires (10'), wire cutter/strippers, and a 16ga splice. I have to replace the clutch master cylinder this weekend & I'll prob go on and nutter to since I have it all. I can always reverse it if something goes wrong (haha I hope).
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Unread 06-23-2011, 02:26 PM   #14
monkeyhouse
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Quote:
Originally Posted by jhumphrey View Post
I have a timing light, 16 ga orange and purple wires (10'), wire cutter/strippers, and a 16ga splice. I have to replace the clutch master cylinder this weekend & I'll prob go on and nutter to since I have it all. I can always reverse it if something goes wrong (haha I hope).
exactly!
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Unread 06-23-2011, 02:38 PM   #15
Peter Nuss
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Ok, now I understand a little better what you are asking. No, nutter will not make a tremendous difference if it's running to your satisfaction right now. People that have done the nutter and added the better distributor have noticed a difference. I know I sure did, I would not say a tremendous difference, but, I would not go back either. My main reasons were to remove the 25 year old connectors and replace them with new GM Weather Guard Connectors, inspect/update the wiring, remove items that can cause problems down the road with no benefit now, and to have components they were designed to work together i.e. simple carb, simple ignition system, simple charging system etc. These are simple engines that were burden with stop gap measures to make them meet smog laws. Sometimes not too effciently. I very pleased with the way it runs now, and not so much before.
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