Engine swap - merits considered - your thoughts

Scramblin_Jim

Legacy Registered User
City
Goodyear
State
AZ
#1
The problems:
1. I'm giving thought to removing my engine to address replacing all the freeze plugs.

2. I also hate oil leaks and it looks like the engine rear seal is leaking getting worse after 3 years and 10K miles since engine rebuild. Previous owner did a quick rebuild as it turns out - what else did he not do?

3. No power - need more HP. On my last trip to Death Valley, I learned just how under-powered my Jeep's 258 is with a T-5 and 4.10 gears. A few times I could only manage 38 MPH going up hill against the wind. Others in my caravan thought I was having mechanical problems. With the weight of a 33-gallon fuel tank and all my camping gear in the back, maybe too much weight for my setup - need more HP?

The issues:
1. Costs. I don't have the space nor time to do this on my own. My home owners association will not allow car overhauls in the backyard which is where I keep my Jeep. Therefore I am considering taking it to a car mechanic friend's shop for him to do the work. Have not talked with him about it yet, but what kind of cost will be expected - labor hours for typical engine removal?

2. I invested in a Howell throttle body fuel injection kit as my first modification to the Jeep when I first purchased the Jeep to get it through emissions. With all the extras I suspect I have over $1300 invested in it. I like fuel injection and want to keep it or if I go to another engine, it must have fuel injection!

3. To keep costs down, do I keep the 258 engine and its 115 HP or go with another engine with more HP? How much engine can the T-5 handle?

This Jeep is my hobby project. Its my de-stress tool from work pressures. Its my learn car mechanics playground and lab for putting trying new things. I use it as my third car. It is the utility truck in addition to my Jeep expedition exploring tool. I go on week long trips with my Jeep club seeing the sights. I don't rock crawl, just do easy 4x4 stuff. It's not trick as I don't want to put money into the appearance but into functionality. All modification I've done were for long trip reliability and easy of use. I have more money into this thing than it is worth.

So all this thought because I have a leaking freeze plug and oil drips. Any comments as what you would do?
 

Randyzzz

Blown Budget
LIFETIME
CJ-8.com Member
SOA Member
City
Redmond
State
OR
#2
I'm no expert on the Jeep sixes, but would a 4.0 swap be an effective power solution? The newer HO versions have 190 HP, and from driving a Cherokee with a 4.0/auto/3.73/31" the power is pretty good. They come injected already, you might be able to sell off your current injection system to offset some of the costs.
 

Scramblin_Jim

Legacy Registered User
City
Goodyear
State
AZ
#3
any other comments?

I read in the forum histories, that headers are not looked on with favorable results for the 258, why? I thought the purpose of changing to headers was to gain performance. Does it impact the torque to much?
 

kohldad

SOA Member
City
Goose Creek
State
SC
#4
Questions:

1. Tire size?
2. What gears do you have?
3. How fast are you wanting to cruise?
4. What ignition system do you have?

If you already have the howell and assume you have HEI, then a simple but proper rebuild may be all that you need. The cost for that should be less than the cost for an engine swap because you will save on the engine cost.

Legal Disclaimer
I reserve the right to change my opinion
upon seeing the answers to the four questions.
 

twmattox

Legacy Registered User
City
Arcadia
State
IN
#5
Something is drastically wrong...

I have a 258, T-5, 31" tires, 33-gallon tank, and 3.31 gears. I have absolutely no problem cruising 70+mph (up-hill with a headwind)...even fully loaded (and I have fully loaded it before). You should be more into the power band than I am (unless you have monster tires).

I would recommend a quick compression check. As stated above, you may need a re-build...
 

pgertz

SoCal Scramblers
City
Lake Forest
State
CA
#6
If you keep the T-5, you can have it rebuilt to the specs of the World Class T-5 (the tranny using in Mustang GTs and Cobras). The upgrade will easily handle 300 horses.
 

bigwalton

Picture cravin' AK Postal nut
Staff member
SOA Member
City
Dexter
State
MI
#7
I'm no expert on the Jeep sixes, but would a 4.0 swap be an effective power solution?
I sure as %^$* hope so! I'm about to start this very thing tonight!!! :thumbsup:


With the Howell already on there, you shouldn't have too much trouble. That's a solution lots of folks go with.

That said, you could definitely sell it off if you swapped out the engine without any problem.

The shop labor is what's going to kill you IMHO. You could specify that they ONLY get it in and get it running and don't have them spend any time thinning the 4.0 harness (or spend $$$ on the pre-made Hesco harness).
 

Scramblin_Jim

Legacy Registered User
City
Goodyear
State
AZ
#8
See comments in red
Questions:

1. Tire size? 33x950R15
2. What gears do you have? 4:10
3. How fast are you wanting to cruise? 65MPH
4. What ignition system do you have? DuraSpark

If you already have the howell and assume you have HEI, then a simple but proper rebuild may be all that you need. The cost for that should be less than the cost for an engine swap because you will save on the engine cost.
no HEI
I have no problem going 75 MPH on flat land. It was the hills and the wind that eat up my power. First time I had really felt that under powered.

I would recommend a quick compression check. As stated above, you may need a re-build...
When I first purchased the Jeep two years ago, I did a compression check. From what I remember all of the cylinders had values over 150, and a couple in the mid 160's.

That said, you could definitely sell it off if you swapped out the engine without any problem.
What would be a good inexpensive yet powerful and fuel effecient engine to consider and maintain the T-5?

The shop labor is what's going to kill you IMHO. You could specify that they ONLY get it in and get it running and don't have them spend any time thinning the 4.0 harness (or spend $$$ on the pre-made Hesco harness).
I'm looking at taking the Jeep in and removing the engine and installing new freeze plugs all around. I also need to replace the main seal and check out the clutch. I most definately will check the compression at that time. Any other things to consider?
 

bigwalton

Picture cravin' AK Postal nut
Staff member
SOA Member
City
Dexter
State
MI
#9
What would be a good inexpensive yet powerful and fuel effecient engine to consider and maintain the T-5?
I'd definitely go 4.0 for simplicity, but you're pretty close to that with the Howell on what you already have... the 4.0 is more modern in all respects and a bit more efficient.

33s with 4.10s sounds like a little low on the gearing to me... I had 33s and 3.54s and thought that was a nice match.

Any chance you could find a set of 35s somewhere to borrow and run to get the overall gearing up some on the highway?
 

Scramblin_Jim

Legacy Registered User
City
Goodyear
State
AZ
#10
Any chance you could find a set of 35s somewhere to borrow and run to get the overall gearing up some on the highway?
I went with the 33's because for now I have armstrong steering and felt I would not be able to steer the thing at low wheel'n speeds. I do have parts for a power steering upgrade, just haven't got to installing it yet. Still need the intermediate shaft as I understand the manual and power steering shafts have different couplings.

Anyway, you think bigger tires will improve highway performance - interesting - had not considered that. Figured the bigger tires would just rob more power due to their weight increase.
 

twmattox

Legacy Registered User
City
Arcadia
State
IN
#11
Actually, all you need is the bell coupling. This costs around $20 or so and on one end connects to the intermediate shaft on the other end connects to the steering gear.
 

bigwalton

Picture cravin' AK Postal nut
Staff member
SOA Member
City
Dexter
State
MI
#12
Anyway, you think bigger tires will improve highway performance - interesting - had not considered that. Figured the bigger tires would just rob more power due to their weight increase.
It's the gearing change that it will get you that I think could help.

When you're doing 65 on flat ground, what RPM are you turning?
 

okjeep

Basic User
City
Tulsa
State
OK
#13
though this is from my wife's 89 yj, the overall results are in line with your expectations. i upgraded her 258 with a weber carb with less than acceptable results. Then pulled it all out and upgraded to a 1000 mile fresh 4.0. It was better but still not it (running 35's and 4:56 gears). The highway driving was exhausting. Either winging the engine to maintain or drive on the shoulder to not get run over! Ultimately, it all got pulled out and replaced with a 2003 5.3/700r4 combo. I knew when I did the 4.0 that I should have just 8'd it at that time but didn't. Sure I saved some costs but in then end, only doubled them as well as time.

Moral, if you want power, add cylinders.
 
City
White Rock
State
NM
#14
Brother I feel your pain....... I have a very similar set up although I swapped in a 999 auto trans and do have PS. I run 4.10s, 35s and can run 60-65 no problem as long as it is level or in decline, teh speed drops off precipitously with an incline and 35-40ish is frequently the case if there is a significant grade or a long grade. I live at 6000 ft right next door in NM and am frequently between 4000 (Moab) and 11000 (Colorado).

First off, going to 35s will not help, trust me, it will drop engine speed at a given road speed by a couple hundred RPM, but it will NOT help in the power department. Moreso if you also go from 9.5 to 12.5 in width.

2nd, headers don't help much and are a huge PITA to deal with, a couple friends did this mod and all had the same conclusions, not worth the time, trouble and increased maintenance. One went off brand motor/trans (chevy of course) and the other is dwadling along talking abou ta 4.0 head swap. Others are just waiting fo rth eheaders to ultimately fail or a dela to fall into their laps

The options I have/am considering are the following
1) 4.0 L swap - I'm reluctant to do that because of a couple of things, one my engine is absolutely solid and it seems like a waste, second, if I were to do that I would feel compleed to do the AW4 swap too which drives cost up and I then have a solid 258 and a 10k miles 999 laying around that I have sunk to much $$ into already and third, I don't know for sure that it will be the solution.

2) 4.0L head and EFI - cheaper and easier than the 4.0L/AW4 and is supposed to yeild a solid 40-50 HP with no other mods. It was/is my leading candidate but I am reluctant to go this route for a couple of reasons as well. First, I don't know, really, if it will be the solution, nobody I KNOW has done it, all the folks I have contacted swear it's the be all end all, but how much of that is because that was their choice for their application? will it be my choice once complete?

3) 360 AMC - I have the motor and I have the motor mounts, need the brackets, Carb/EFI and incidentals. Haven't done anything yet for a couple of reasons. first I don't have the place or the drive to do it, the jeep just works to darn well everywhere else. Second, I should rebuild the motor before I install it, it has low miles but has set for years. More $$$. Third, I just don't like wrenching on the darn thing anymore which means finding someone to do it fo rme, $$$ and I will not be happy with whomever does the work. and Lastly, i would then need to do some form of EFI as well.

4) Off Brand motor swap - Money, it's not jeep, and would also need a new trans, I don't want to do the work, all of which leads up to giga $$$

5) MC 2100 carb swap - cheapest by far, orders of magnitude if you find a rebuildable in a yard and put a kit in it yourself. I did this to my son's and, coupled with a Jacob's high energy ignition, it runs great. His is much like yours in that it is 4.10s, T5 and 33s. Of course since you have the Howell already this doesn't help much....

So, that's what I have learned so far. I wheel primarily in 2 wd low, run pretty high tire pressure on the highway but with your 9.5s I probably have about the same contact width. I do get about 14.5-15 mpg on the highway which is OK but not the 18-18.5 I was getting with the T5.

I'll be very interested in hearing about your decision and how it goes....
 
Last edited:

Randyzzz

Blown Budget
LIFETIME
CJ-8.com Member
SOA Member
City
Redmond
State
OR
#15
Again, I am no expert on 6 cyls, but I'll add my .02... The sixes I've had are a 4.0 in a Cherokee, and a 225 and a 231 V6 in my Jeepster. The v6's, especially the 225 are good down low, but suck at highway speeds. A stiff headwind really knocks them flat. The 4.0 in the Cherokee is another story. It has plenty of power, and it gets good mileage too. The Cherokee has 3.73 gears, AW4, and has had from 30 to 33" tires on it. The 33's did hurt the performance or mileage, but not much. But, no substitute for a V8. I hear all the time about how great the 258 is, and I agree...in certain applications. The guys lovin' on the 258 talk about its low end grunt, and how great it is wheeling. Never heard anyone say how much they like it at freeway speeds. If your Jeep is a dual purpose vehicle, I'd say the 4.0 is a minimum. Bare minimum- keep your gearing and tire size in the sweet spot. The only tried and true way to get good highway and off road power is with a V8, IMHO. That's why I chose the 5.3 Vortec. Power to burn (the tires:D) and good economy (many reports of 26ish at 65mph) made my decision obvious, for me. But, I do appreciate those who want to keep their Jeep all Jeep, and then a 360 is probably the most economical and easiest choice.

Remember- you can always take your foot out of the throttle...but once you hit the floor, that's it, brother. I'd rather have more power than I could ever use than wish that I had more. And- a large engine barely working is always a better scenario than a smaller engine regularly working near it's capacity.
 

John N

Addicted....Ex-SOA VP
LIFETIME
CJ-8.com Member
SOA Member
City
Rockville
State
VA
#16
What I've got....

I have an AMC 360, very mild (to the point of being a weak 360), but it does put out plenty of power to run at highway speeds. It has a Howell TBI and DUI ignition. I have a TF999 behind it. I am satisfied with the power, but in the future, want to put in a more potent 360. I've thought about a 401 and have had a built one in a FSJ, I'm afraid of cooling issues on these. I have 33's with 4.09 gears, too. Crawling isn't an issue with a 4:1 tc.
 

MarknessMonster

Amiable Jeeper
City
Western
State
CO
#17
After reading all the replys to the original post, I'd like to participate in this discussion, but cannot provide any helpful solutions. I've had the same problem, but haven't figured out the remedy.

When I was about 18 years old and living at 10,000 feet in elevation, I knew a young gal with a stock '83 258-CJ7 that would really scoot up the mountains. On some occasions, I followed her in my stock '81 CJ8 with 31" tires and 2.73 gears. I always had a ridiculously hard time keeping up with her, as my rig was such a dog on the hills. At some point in time, I switched to 4.10's and 33" tires, but it did little for me on the hills.

I always considered my plight was the result of an Illinois Jeep not being set-up properly for the mountains. Being under-funded, I never did anything about it. That Jeep still serves me today, and I've only changed to a T-5 since. It is still a dog at 6000+ feet in elevation when running on an incline at high speeds.

So, I was no better at keeping up with the gal's CJ-7 even after my gear swap. I truly felt that her AMC model was set-up for high-altitude applications through a carb adjustment or cam specification, and that it just breathed and pushed better with less air. In later years when I bought my Ford pick-up, it specifically stated on the window sticker that it was set-up for H/A use; I still don't know how it differs from a low-altitude model.

Regardless, my input to this discussion is simply to relate that there may be a missing piece of information here that would benefit the original poster. I don't know at what altitude he's having a problem, but AZ has some high points of elevation too. In other words, if my experience showed two stock CJ's that performed so differently on the steep mountain drive, there must be some common (i.e. stock) set-up that can be done to a 258 that allows for better performance at high-altitude.

Maybe we need to bring in the Jeep experts, as I'd love to find this solution.

BTW, my '83 has an AMC360 with 3.54 gears, 33" tires and a T-176. It will scoot up the mountains, but I can obviously still feel the strain from the high elevation.
 

Scramblin_Jim

Legacy Registered User
City
Goodyear
State
AZ
#18
Wow I feel much better now knowing others are experiencing the same problem. If I recall correctly, I am doing about 2800 RPM when going 65MPH. Having just completed the change out from 2.73 gears with the 33" tires to the 4.10's I have definately noticed less room at the top end for freeway driving. However when wheel'n it is great when in 4-low as first gear is like creeping along and works great on the really tough loose stuff. I was thinking maybe 3.54's would have been a better choice but that would probalby have made the up hill climbs against the wind even worse.

I don't recall the exact elevations I was at when experiencing the problems but I was coming out of Las Vegas and heading west into Death Valley. These would have been low elevations, nothing like Colorado 9000 -12000 ft stuff. The big thing was it was a very windy day with wind gusts about 45mph and a head wind of maybe 30 mph. Death Valley was definately blowing across the road in front of me. I had to keep on my toes as the wind gusts were tricky keeping the Jeep in the center of my driving lane while going 45 mph. It was very noticable when the wind was pushing from behind me verses heading directly into the wind or going across the wind direction. It made for a long trip.

I had considered the 4.0 L head swap but didn't know if it would be worth the time and touble to gain a few HP. 30 HP might be acceptable increase. But do I get to keep the same throttle body setup with the Howell on it?

Another point I should make in helping to come to some sort of conclusion on this is the Jeep has about 197K miles on her. Now the PO said he had the engine and transmission rebuilt but I really don't know how many miles ago. They both seem strong enough and it doesn't have any excessive oil burning coming out the tail pipe or shifting problems. I had to put in a quart of oil after about 1200 miles during this last long trip, is that excessive oil consumption? Emissions seem to be very good when I have to go thru the mandated testing each year.
 

bigwalton

Picture cravin' AK Postal nut
Staff member
SOA Member
City
Dexter
State
MI
#19
Wow I feel much better now knowing others are experiencing the same problem. If I recall correctly, I am doing about 2800 RPM when going 65MPH. Having just completed the change out from 2.73 gears with the 33" tires to the 4.10's I have definately noticed less room at the top end for freeway driving. However when wheel'n it is great when in 4-low as first gear is like creeping along and works great on the really tough loose stuff.
I'm in this same boat, having chosen 4.56 gears when I built my waggy axles, but I also was targeting 37" tires. Great on the trails and around town with the 35s, definitely lacking on the highway. About to fix that though :D
 

MarknessMonster

Amiable Jeeper
City
Western
State
CO
#20
My AMC258 has about 260K+ miles on it now, and without a rebuilt...what a great little gasoline motor! The performance hasn't really changed since I purchased it in 1988 with 60K miles, except for the modification changes noted previously. The power issue on steep grades hasn't changed much, so I don't think it is a matter of the motor being "tired".

Additionally, your comment about burning a quart of oil in that short time is odd. I don't drive mine like I used to, but even at 240K miles when it was still my DD, it still didn't burn any oil between 5K mile changes.

BTW, when I drove the Jeep from IL to CO in 1989, I was only able to travel at a speed of about 45mph on "flat-lands" I-80 through western Nebraska, due to a strong head wind in January. When a semi would pass and block the wind, my speed would instantly jump and then dissipate as the truck distanced itself from me. I remember wishing that one of them would slow up for a minute and let me draft him all the way to CO.

I still believe that there is a standard/stock set-up to correct this power issue.
 
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