1986 258 inline six swap to a 1991 4.0 H0 fuel injected motor

1986 258 inline six swap to a 1991 4.0 H0 fuel injected motor

Quick2

Jeeper
Posts
28
Thanks
0
Location
Somonauk
Vehicle(s)
1986 CJ7, dana 44 rear axle, dana 30 front axle, lifted ? inches, Goodyear Wrangler MT tires-33-12.50 R15 LT
Changing the 258 inline six in my 1986 CJ7 to a 1991 4.0 HO fuel injected motor.
Does any one no what to do about a wiring harness. Also I have read the knew motor requires a Crank position sensor in the bell housing. Not sure what other mods I will need to make this work.
 
the CPS keys off notches in the flywheel, I think you should be able to use the 4,2 bell with the 4.0 flywheel and do a little creative machine work on the bell to hold the sensor. may be a bit of a challange to find a flywheel unless you are running an automatic.
I do hope you take lots of pictures of this one. this is a an epic swap.:D
 
Thank you for the link. I think it will be a big help.
I only have had this jeep for a couple days. I got the 1991 4.0 H0 TPI from a 1991 Cherokee sport yesterday at a junk yard. The motor was replaced with a new one from the factory awhile back . He started it up and it ran great. The guy changed the oil every 2500 miles.
I think it is a 8 in spring-lift. The person I got it from was not sure. I am putting a link to some pictures of the start of the project on here. On one picture there are two jeeps. One is a stock wrangler. I measured the difference in bumper heights. The CJ7 was 8.5 inches higher .

Here is a link to pictures of the 1986 CJ7 project-
Pictures by Cj71986 - Photobucket
 
at your first opportunity will you measure from the center of the hub to the ground and from the top of the drivers side body mount, right under the drivers feet, to the ground?
this is mostly for my own curiosity, It may or may not tell you anything.
I am not sure that comparing it to a wrangler is exactly apples to apples.:cool:
 
Measuring the ride height in a Jeep without Any motor/tranny is kinda hard. Those springs look pretty fresh.

You know it's going to squat down quite a bit, once you have everything installed, right? Look like 4" to me.

And Judging by the rear hangers you have bolted up to the front, those Two inch wide springs are a definite upgrade.

91 4.0 HO, Sweet!
 
Last edited:
do it anyway.
we can see how much it drops.:D


Measuring the ride height in a Jeep without Any motor/tranny is kinda hard. Those springs look pretty fresh.

You know it's going to squat down quite a bit, once you have everything installed, right? Look like 4" to me.

And Judging by the rear hangers you have bolted up to the front, those Two inch wide springs are a definite upgrade.

91 4.0 HO, Sweet!
 
The jeep is at a friends farm. Only a couple miles from my house. I might get over there today and i'll measure it. I agree that measureing the wrangler and cj is not the same. It seems to be lifted nicely though with a good spring lift. Sure looks cool:)
 
At this point its missing the engine and drive shafts. I was told the transmission is good. Not even sure if its a 3 speed manual or 4 speed. Can any one tell me how to check this out? Oh ya I forgot. when I took the pictures all the missing parts where in the back. Even the heads , crankshaft and the manifolds . The 258 Inline six was taken apart for a overhaul.
 
get some pictures of your transmission, we may be able to ID it.:D


At this point its missing the engine and drive shafts. I was told the transmission is good. Not even sure if its a 3 speed manual or 4 speed. Can any one tell me how to check this out? Oh ya I forgot. when I took the pictures all the missing parts where in the back. Even the heads , crankshaft and the manifolds . The 258 Inline six was taken apart for a overhaul.
 
at your first opportunity will you measure from the center of the hub to the ground and from the top of the drivers side body mount, right under the drivers feet, to the ground?
this is mostly for my own curiosity, It may or may not tell you anything.
I am not sure that comparing it to a wrangler is exactly apples to apples.:cool:
I measured it like you asked. 16 3/8ths to center of hub and 27 3/8ths to top of driver side body mount by the door. Gonna need some rocker protection with a step to make it easier to get in. I'm not a spring chicken anymore. LOL
Tomorrow I will take some pictures of the transmission. I will also try to get the number on a tag and stamped on it. Its been painted black . Kinda hard to read.
 
I have also been thinking of using the 1991 4.0 HO with my 1986 258 intake manifold, a carburetor and a header. That way I wont need the 4.0 wiring harness . The problem here is that the 86 intake and exhaust is one piece. Or at least it appears to be. there must be away to separate them. Or just to make it even easier i could just use the intake and exhaust off the 86. I would be nice to make it a rolling project. Could always upgrade it later.
Lots of possibilities.
 
I have also been thinking of using the 1991 4.0 HO with my 1986 258 intake manifold, a carburetor and a header. That way I wont need the 4.0 wiring harness . The problem here is that the 86 intake and exhaust is one piece. Or at least it appears to be. there must be away to separate them. Or just to make it even easier i could just use the intake and exhaust off the 86. I would be nice to make it a rolling project. Could always upgrade it later.
Lots of possibilities.
If you want a carb just use a 4.0 head on your 258. I think the hole point of the 4.0 swap is the fuel injection.
 
^^ he is right ^^
if your not going to use the EFI it is not worth the effort.
And I believe you have a 5 to 6" suspension lift.
 
The 4.0 heads do flow better than the 4.2 258

4.2 ports are "L" shaped, down to the valve. 4.0 heads smooth the corner out. 4.0 HO radius it further. I think the exhaust valves are bigger, too

That said, going with a Carb to try saving a few headaches with wiring and fuel delivery isn't worth it. IMHO.

Lots of people have done the 4.2 in a CJ swap. Many have documented it.

There's a lot of little grinding and fitment work to be done putting a 4.2 intake on a 4.0 head. And you have to fit a 4.0 exhaust on it. More fitment issues.

Probably cam issues, possibly distributor issues.

If you want to be up and running in a shorter time, for short money,
With the least headaches possible, swap the whole motor, with the EFI.

If you have spare time, patience and money, you can build a sick carburated beast with a 4.0., but only with a performance carb intake.

The intake heater kills the flow, totally.
 
The original motor is gone. It was all tore apart. crank was out it was just a block. I didn't want to rebuild it. If anything I will just buy a rebuilt long block 258 and put it in. I was told by the guy I got it from that he was gonna put a header on it and change the intake manifold and put a better carb on it. Nothing is written in stone. Just trying to figure out what would be the most cost will be on various options. I have been doing some research on this. I have only had the jeep since 3-7-2012. I seems the wiring harness for the engine swap would be over a grand. At that price maybe I should put a v8 in the jeep. I see there are threads and info on putting in one. I am gonna try to get the best bang for my buck. At this point I am currently researching the option of purchasing a new long block 258. But I would at-least like to put headers on it and upgrade the intake and carb. If any one know where to get the parts or if this would be a little less painful on the budget, please let me know.:confused::confused:
 
If you are doing that swap and have the 258 parts you might want to look into stroking that 4.0 while you are at it. It's fairly common to do when converting. This would be nice long term option if you are in no hurry and want to build it once.
 
Thanks for the option info. I am not in a big hurry. I would like the motor i put in to last awhile. Then I will be doing some body upgrades while I am driving it.

I just got off the phone with Hotwireauto.com . They said I could get the wiring harness from the 1991 4.0 H0 made to work with my 1986 CJ7 harness for 685.00 . I just send them the 4.0 harness and the fuse block were it goes into the dash on my 258 harness and they will make it work.
I still have to figure out how to hookup a crank position sensor on my jeep or use the automatic trans from the donor 1991 Jeep Cherokee Sport.
Hotwire told me there is a company called Hesco that might have a CPS solution. So time for some more surf-in the web to find them and give them a call.
Half the fun of fixing this jeep up will be the journey to get there. But it has to work when it gets done or it will have been for nothing. That would suck!!
 
Went to Hesco website. They have a complete kit for this engine swap. I will still need to get a different distributor. The kit will not work with a 91-93 distributor.
Never changed one of those. Cant be to hard can it.:)

Product: Complete Retrofit Kit 91-95 Manual #HES6109195
Price: $1,725.00
Description:
These kits are for individuals who have a 4.0L engine only and need the necessary components to complete the conversion. For 1994-95 4.0L engines only. 1991-93 engines will need to have a 1994-95 distributor. The distributor pick up in this kit is not compatible for 1991-93 distributors. Kit consist of the following:

Wiring Harness
M/T PCM
Crank Sensor/Damper Kit
Speed Sensor
Rear Mount Fuel Pump/Filter Kit
Throttle Cable
Air Filter Assembly
Fuel Hose for Pump
Vacuum Lines
Map Sensor & Bracket
Fuel Lines to Rail
Coil
Distributor Pick Up


Part Number: HES6109195
Manufacturer: Hesco
Application 1: 1991-1995 4.0L engines MANUAL transmission
Application 2:
 
I was thinking about going this rout because I am sick of the crappy carb on the 258 and really want fuel injection. But now I'm leaning to putting Fuel Injection on my 258. Fuel Air Spark has a new kit with everything you would need but air cleaner for 1769.99. Looks pretty sweet.
 

Jeep-CJ Donation Drive

Help support Jeep-CJ.com by making a donation.

Help support Jeep-CJ.com by making a donation.
Goal
$200.00
Earned
$210.00
This donation drive ends in
Back
Top Bottom
AdBlock Detected

I get it, I'm a Jeep owner and ad-block detectors kinda stink but ads are needed on this site. This is a CJ site, all the ads are set for autos (some times others get through.) I cannot make them just for Jeeps but I try.

Please allow ads as they help keep this site running by offsetting the costs of software and server fees.
Clicking on No Thanks will temporarily disable this message.
I've Disabled AdBlock    No Thanks