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Discussion Starter · #1 ·
Hi everyone, I drive a 1989 YJ with the stock i6. I just started looking into ignition upgrades and was wondering if upgrading to an hei distributor is something that may be worth my time. The PO did the nutter bypass already but it is still pretty rough. I just wanna know the advantages of the hei, the work/time required and the parts that any of you might have used.
In advance thank you all
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Put one in my 89. Only takes a few minutes (30-45), If....

If you have everything ready to go and pre-read the instructions, or are familiar with a dist installation. the dist goes in just as any other make sure you are checking your rotor upon exit and to install for proper timing, get the rotor to #1 TDC. before pulling old dizzy, mark the rotor position alignment. saves you time if you take this part slow and steady.

The plug wires will change completely, I bought an Accel kit and made mine up myself
took me about an hour and a half doing them one at a time. There's a few other guys out here that have found box sets ready to go from other Inline 6 motors. I'm sure they will offer up their sources .

Get the 2 wire pigtail for the electrical to the dist when you order. makes for a nicer install and you will want the extra 12 inches of wire IF you dont want to rip into your wiring harness.

The Only 2 wires you need are the tach off the coil and the 12v keyed on from the old Dist. should be connected to one of the solid yellow wires from the PO's bypass.

Have a timing light handy, and it might be a good time to replace the vacuum advance tubing while you're at it.
 
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Whats the benefit of the HEI over the stock
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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My simple explanation. HEI has an integrated coil, eliminating the coil next to your dipstick, Takes the place of the Nutter Bypass, running straight off 12v power from your key on ignition switch thereby giving you direct spark and bypassing the computer, ergo less "No Spark" issues.
Biggest benefit is it Steps Up the voltage to your plugs giving you better ignition to your cylinder, more complete fuel burn and in theory better mileage, performance, etc. I guess that's all relative to everything else being in sync, fuel, emissions, Cat etc.

I did my 89 with one in conjunction with a new Carb. HEI went in a couple weeks before and I can honestly say there is a noticeable difference in performance. I have yet to have any complaints.

Did learn an important lesson this week. Just because you upgrade the dizzy, Stay with the OEM Spec. Copper plugs. I bought some way more expensive Irridium plugs and they don't perform as well as the $2 cheapies.
 

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Eddie and Kaz, The best place (in my opinion) to buy a HEI distributor is Summit Racing. They have tech help if you get into a problem and can advise Kaz if there is a HEI for a 2.5.

GotItAtLast recommends to buy the pigtail at the same time as you buy your distributor. With the pigtail, the install is a breeze, without it, the install could be a nightmare.
For $8.00 I think it's a no brainer.

I had a problem with my timing mark (flash) jumping around when setting my timing. I guessed I had a worn distributor. Once I had the HEI in, the timing mark (flash) was steady and I could be certain of how many degrees BTDC my timing was set at.
Seat of the pants says Jeep runs better.

Good Luck, L.M.
 
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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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So what brand/model did you use for the distributor? What fits the motor?
Got mine from Summit, a few bucks more than some, But tech help was there when I called and tremendous help, not sure that's available on Amazon or Ebay.

Summit has a make and model Part Finder on their site, Use it and you wont go wrong. Free 2 day shipping over $99. Get everything at once and save on shipping.
 

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Discussion Starter · #11 ·
Yes, I understand with the hei the nutter is no longer used. Thank you. I ordered all the parts so I'll do a full tune up and hopefully post a step by step for anyone who needs it
 

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I don't remember if the instructions that come with the HEI tell you, but you will need to re-gap your spark plugs to .045" to .050".

I don't remember any complaints about the HEI upgrade being posted here.

Good Luck, L.M.
 

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thanks for the info - good help. I am putting an HEI on a 4.2L YJ engine, with a Weber on it. Any issues with the vacuum line from the Weber throat to the distributor? The instructions say do NOT do this, but other threads say absolutely DO it...!?!?

And do I really rip out the old/current ignition control module?

Thanks
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Borrowed this from my install info. describes the two types of vacuum. Not sure what's up with the Weber directions.

There are two types of vacuum pull that you will need to understand. They are “ported”
vacuum and “manifold” vacuum. It is EXTREMELY important to know what type of
vacuum source each port is pulling, and to know and understand which vacuum source is
needed for each device. Example: Your distributor advance needs ported vacuum. The
ported vacuum pull advances your distributor timing as you accelerate. If by chance you
tie into manifold vacuum by mistake (and properly adjust your timing) you will actually
retard your timing as you accelerate. This is BAD by the way and you will be very
sluggish off the line and at WOT.
Ported Vacuum
-Ported vacuum is drawn in when the throttle is opened up. This draw is increased as
more air is sucked into your air through cleaner and down through the venturis. Ported
vacuum is highest at W.O.T. and lowest (or non-existent) at idle. You will have almost
no vacuum pull at idle with ported vacuum unless you have moderately high idle speeds..

Manifold Vacuum
-Manifold vacuum is drawn when your throttle is closed or at idle to very low driving
speeds/RPM’s. This is everything under the carb. It is highest at idle and lowest at
W.O.T.
Checking Vacuum Type
The easiest way to check vacuum ports and telling what type of vacuum they are drawing
is to start the engine with the vacuum ports capped off and uncap them one at a time.
Once you uncap the port, touch the opening with your finger (at idle) if it sucks on your
finger tip it is probably manifold vacuum. Increase to full throttle, the suction should
dissipate. If the vacuum is ported, it should have little to no suction at idle and should
start to draw respectable suction as acceleration is increased. Ported vacuum will reach
peak suction at W.O.T

Hope this helps, If you don't have one already, invest in a OTC vacuum pump, Invaluable for setting timing on new HEI and Carb adjustments.
 

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thanks for the info - good help. I am putting an HEI on a 4.2L YJ engine, with a Weber on it. Any issues with the vacuum line from the Weber throat to the distributor? The instructions say do NOT do this, but other threads say absolutely DO it...!?!?

And do I really rip out the old/current ignition control module?

Thanks
As long as you don't have to pass emissions, the HEI is a great upgrade.

Since you are getting conflicting statements about how to send vacuum to your distributor, why not follow the instructions and start with the manifold vacuum, and if that doesn't work well, you can always switch to a vacuum port on the carb.

You don't have to do anything with the PCM, the ICM nor the wiring. Some of us remove those things to make a cleaner underhood and underdash wiring system.
Since the modules control the carb and timing and the Weber and the HEI are not electronically controllable, the modules are superfluous.
It's a real pain in the neck to remove all those things. I don't blame you for not wanting to do it if it isn't necessary.

As far as running rough, Quadratec has a manual on servicing the Weber carb. If I was running a Weber, I would be sure to own one.

Good Luck, L.M.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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And yes almost everything else goes, but do it in small pieces so you don't cut, pull,remove,destroy, anything without making sure everything is still working
 

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Got it at last types faster than I do. Read his explanation about vacuum to the distributor an I suggest that you follow it.

I printed it for my general Jeep information folder. It's valuable information.

Good luck, L.M.
 

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Thank you all for your input. As a former motorcycle road racer, I understand small incremental changes one at a time. But there is so much "art" in getting these Jeep things to behave that it is not coming super easy! I read a long treatise on ported vs. manifold vacuum by an expert (in here somewhere) and he says do NOT do what Summit says (use ported vacuum) because they have no idea about anything - or something to that effect... I do think that it makes sense for increased vacuum with throttle and rpm to want to increase advance, which points to ported vacuum... But he says that will destroy the needed advance for idle and cruising (I guess I would need to know how the vacuum is used in the HEI).
I am going to leave the ICM in place and patch in the HEI electrically, THEN clean up the bay when we do the next horror show which is replace the leaky heater core.
I am also going to see what I can do about the Weber (thank you for the tip above) and pray I can make all these pieces come together. Based on what I have read I have to believe that the HEI/Weber combo should be a decent combo. Completely rebuilt motor, rebuilt AX15, welded frame... Want this puppy to run well!
Thanks again and I will report out how I untangle myself from the web I am currently stuck in!
 

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so... do I have to start another thread to get your advice on how to stop my @*&@^#(*&@ oil pan gasket from leaking (front right corner)?
New silicone gasket? YES, second one
RTV on the corners? YES
careful torquing from the center out, in multiple steps? YES
Still leaking, third try? YES (not horrible but I HATE that wet spot under the engine)
 
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