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post #1 of (permalink) Old 02-11-2004, 11:40 AM Thread Starter
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BIG step in my SBC conversion

Well I have finally taken the first big step in my SBC.
This past weekend I pulled out the old 2.5L motor out along with the ax5 and the old trans case. The drive shafts are also gone. It feels good.

I have a question for those who have done a Carb SBC into a YJ.

How did you deal with wiring the "NEW" Jeep. One of my objections in this rebuild is to totally simplify the wiring. The PO of my jeep really tore into the factory harnes. And I know I will no longer need all of the Fuel injection stuff, or the computer.
The task of picking out what I don't need, and trying to figure out what I do need seems like a huge task to me. And one I do not think I can do.
What I would like to do is to remove all the wiring... And I mean all of it, and start fresh, and make it simple. Very few things that are electric. (I may not even have dash lights)
Can anyone recomend a kit? I have heard good things about painless, do they have a SBC conversion for the YJ, their catalog only lists stuff for CJ's
I am very interested in hearing what others who have put carb Small blocks in YJ's have done
Thanks for any help.
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post #2 of (permalink) Old 02-11-2004, 06:02 PM
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Re: BIG step in my SBC conversion

Any wiring job can be made simple if you stick to a few basics.

1. Start with the battery, ignition switch, starter, and engine ignition parts, like the ignition coil. The ignition switch has just a couple positions, "OFF", "ON", & "START". Just get a universal ignition switch, drill a hole in the dash and your done. A fusible link from the battery to the ignition switch is a good idea.

2. Then get the charging system working, it's easy with a one wire alternator. One wire from the alternator to the battery, easy.

3. Last comes the lights, get a universal light switch to get the head lights and tail lights to work. A fuse between the battery and universal light switch is a good idea. Don't forget the ground wires to the lights.

4. Pay someone to get your brake lights and turn signals working.

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post #3 of (permalink) Old 02-11-2004, 08:19 PM
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Re: BIG step in my SBC conversion

Ted...at this point I am a little concerned. Without knowing the specific smog laws in your state, I think you may have a problem putting an 84 motor in a 91 vehicle. You can always put in a newer motor, but the other direction is usually a no-no. In CA, it's NO-WAY.

Should you ever decide to move to a state that has tighter smog laws, you will never get it registered.

I hope you did your homework...and I hope you get to keep what you got.
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post #4 of (permalink) Old 02-11-2004, 09:05 PM
 
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Re: BIG step in my SBC conversion

Keep all of your accessory wiring, ie. lights, gauges, etc. Just scrap the cpu and all the engine stuff. The only original Jeep wire going to my 350 is the ground that runs through the ignition switch to the starter solenoid. With no extra vacuum lines and sensor wires the 'ole engine bay looks naked...and very simple.
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post #5 of (permalink) Old 02-12-2004, 08:59 AM Thread Starter
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Re: BIG step in my SBC conversion

Dave thanks for the words of advise. They are handy. I think that I am going to go with a dash mounted ignition. I am going to use a Keyed on off switch, and a push button start. I feel pretty good about being able to get the Ignition working, and probably the alt too. I am not so worried about wiring the actual motot, as I am the rest of the Jeep. Things I am worried about are the fuel pump (I am using my orig electric in tank pump) And then lights.
I am also very worried about taking out the FI wiring. I am worried about screwing up the rest of the wiring for the Jeep. The more I think about it the more I think it is a good Idea to totally start from scratch with a totally new harness.

I have done my homework on this project. It has been in the planning for a very long time. (long story)
I am not putting in an 84 Motor. I have an 84 CJ, that is currently my daily driver. The YJ is a 91, and I am putting a brand new GM performance 350 in it. I am not ver worried about the leagal stuff. There is no sniffer test here, and state inspection can be a bit of a joke. In my 6 years of owning Jeeps, not one of them has ever been "Street Legal" But I haven't every really had a problem getting the sticker on the window
Thanks for the advise.
Does anyone have an opinion on tearing everything out and going brand new harness from painless... Is it really painless?

As a side note, with the new motor the jeep will get all new guages. Mind currently don't work that well anyway, and I am going to use all mechanical guages, so those will be very easy to wire.
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post #6 of (permalink) Old 02-12-2004, 10:52 AM
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Re: BIG step in my SBC conversion

</font><blockquote><font class="small">In reply to:</font><hr />
all mechanical guages, so those will be very easy to wire

[/ QUOTE ]

plumb?
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post #7 of (permalink) Old 02-12-2004, 12:25 PM
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Re: BIG step in my SBC conversion

The wiring kits available from Painless are OK. The wires are marked for what they do, right / left tail light, head light and the like.

In my humble opinion, it's much easier to re-work a few of the wires from the original harness, and add only few new circuits or wires. I really like the wiring diagrams offered by Mitchell's Manuals. Send me a private email and I'll send you a photo copy of your original equipment wiring harness for free. I also have learned how to use a volt meter, so wiring is not that hard for me.

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post #8 of (permalink) Old 02-12-2004, 11:24 PM
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Re: BIG step in my SBC conversion

You should find that the bulkhead connector is split into 2 halfs- one half is for the lighting/horn/ect, the other half is for the engine controls. From this half you need to determine which controls on your replacement engine are also on the old engine. I did my 350 swap into an 82, but things should be somewhat similar. The HEI distributor wire requirs one hot wire-preferrably 10 or 12 ga, for power when the key is in on or start. The starter requires one thin wire, hot in the start position, and the battery cable. You will have the oil pressure sender, the coolant temp sender, each a thin wire to feed your gauges. The alternator has a hot wire to the battery, and a thin wire feeding back into the cluster. If you have an electric choke, another hot with key on wire is required. If you can find a factory wiring diagram, finding which wire performs these functions on the old engine, and using them on the new engine, is optimal. Lastly, the fuel pump. You're going electric? The OE pump is too high pressure/flow for a carbureted motor, an aftermarket electric can be wired into the old circuit, and the pump can be removed from the tank and replaced with a bypass hose, or a mechanical pump used. As for the excess wires, bundle them securely, and tuck them down in the black hole underneath the brake booster. Or selectively remove them. This is all easier if you use aftermarket mechanical gauges and a cable driven speedo. If your current speedo does not use a cable but a speed sensor, be sure to leave the wiring for that intact.

If you are capable of performing the mechanical end of the swap, then the electrical end is just alittle more learning, and careful execution of plans. I definately would use the factory wiring, even if you only use a quarter of it, as opposed to replacing the whole thing.
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post #9 of (permalink) Old 02-13-2004, 12:05 PM Thread Starter
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Re: BIG step in my SBC conversion

The running opinion seems to be to modify the stock harnes and use that. Maybe I should start rethinking tearing the old one out. I guess before I make a final decision I need to really take a good hard look at how badly mine has been altered.



My main reason for wanting a new harnes was because the stock one has been really torn apart and put back together (not correctly) by a PO. I think that because of this I will have a hard time following... A factory wireing manual isn't going to do me much good because the harness is far from stock, it is a mis-mash of wire, tape, and all manor of wiring mess. not to mention the alarm the PO put it... All those wires are still in the jeep too. There are a lot of them.

I guess my plan of attack will be to first see exactly what I am up agenst. Then decide if I need a new harness, or if I can get by with what ive got.
Thanks for the input.
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post #10 of (permalink) Old 02-13-2004, 12:36 PM
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Re: BIG step in my SBC conversion

</font><blockquote><font class="small">In reply to:</font><hr />
it is a mis-mash of wire, tape, and all manor of wiring mess

[/ QUOTE ]

That's probably the factory part there. [img]images/graemlins/thud.gif[/img]
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