need more power

[newbie80cj7]

have a 1980 CJ7 with a 2.5L 4cyl. i believe this is a stock engine and Transmission . it has fairly big tires on it, can't remember the size exactly. when starting out in first have to rev engine to get going. i'm assuming this is because of the tires. when i get to 4th gear this thing has no power. if i'm going against a 20 mph wind about 45 is top speed. then if i come to a little hill have to throw it down to 3rd to get rpms back up. is this normal for this motor? is there a bigger engine that will bolt right in to this without major changes to tranny, wiring, etc. i'm lookin for a winter project but time and money are not limitless. i believe the 2.5 is a GM motor. would like a 4.3L go right in? Thanks for any suggestions.

 

[Saddle Tramp]

Yes the stock I4 motor in a 1980 CJ is a GM motor, the Iron Duke. The advantage is that you can transplant a GM motor and reuse the bell housing making the 4.3 a good choice but the SR4 Transmission may end up being your weak link. The SR4 is a light duty tranny and combined with big tires and more power could come unglued. All in all most likely the tires with the stock gearing are kicking your tail in the power department.

 

[newbie80cj7]

thanks for the reply. i found a site that explained swap conversions and u r right on. not sure i want spend 5-10 grand to do this.

 

[Saddle Tramp]

Whoa! $5-10K? Must be all new parts with a shop doing the work. Assuming you are trying to keep the fuel injection find a wrecked donor and pick up the whole rig if possible, that way you will have all the computer/misc. connectors etc. at your fingertips when needed. If that isn’t practical just make sure you get everything including the computer, sensors, and wiring harness for the front of the vehicle. If the donor motor is bad and you can get it at core pricing you may want to do it then pick up a remanufactured short block. All the miscellaneous trimmings to an engine including the nuts and bolts really start to add up if you don’t have them but if they come with the donor motor you’re ahead. Your other option is to put an AMC V8 back in (AMC 304 , 360, 401) but you will need to find a proper AMC bell housing and install new motor mounts. The AMC 360 is readily available in the bone yards and since the AMC V8 was an option in a CJ from 1972 to 1980 it is possible to do the swap with all used OEM parts.

No better time than the present to learn how to fabricate but if needed only pay a shop to fab up what you can’t do yourself.

 

[newbie80cj7]

yea, the 10 grand was a complete turn key motor/tranny. after looking around i did see some small block chevys on craigslist for 2-3 hundred dollars. there are also vehicles with bad motors fairly cheap. Not sure if i have the space and know how to pull this off, but would be a good time to learn. especially if it doesn't snow again this year. what's the first step?

 

[cass]

http://www.jeep-cj.com/forums/f2/iron-duke-getting-tired-350-swap-12152/



i am still running the T-4 behind my 350. it is a bit better than the SR4 you have but not much. i replaced my SR4 with a T-4 because it had bad reverse. i dont speed shift it of pop the clutch at all and its holding up good. driving down the highway is a dream now. gets 15mpg if im nice to it. it would get better if i had Overdrive in it.

not sure on total cost of swap.... i rebuilt the motor before it went in. i would guess if you used a used motor v8 or v6 and did all the work yourself, 2 grand would be a good ballpark. any questions dont be afraid to message me.

 

[newbie80cj7]

thanks cass. I researched more from your original post and got on a thread about the guy doing a tune-up and checking the timing and cata litic converter and muffler. the iron duke seems to run out good in 1-3 but once i get to 4th gear its a lost cause if there is a hill or head wind. i just want a vehicle i can drive to work in the summer that will go 55 on a windy day

 

[Saddle Tramp]

yea, the 10 grand was a complete turn key motor/tranny. after looking around i did see some small block chevys on craigslist for 2-3 hundred dollars. there are also vehicles with bad motors fairly cheap. Not sure if i have the space and know how to pull this off, but would be a good time to learn. especially if it doesn't snow again this year. what's the first step?

As most of the regulars know I am a strong proponent of keep your jeep, jeep and that typically means not stuffing a SBC under the hood of a CJ when the 1972 to 1986 OEM bits (earlier years too) are readily available on Craig’s List, in the bone yard, etc. to mix and match a drive train without hacking and whacking the jeep up or the need for adaptors; moving a motor mount or two is the worst of it. I know Jeep used GM engines, I understand that, heck they used a bunch of other GM parts over the years too and basically begged, borrowed, and stole from whomever they could get to sell to them, so you could say what really is “Jeep” but….. It’s just the way I see it. However, as far as a 4.3 swap in lieu of an Iron Duke or the Dauntless Buick 225 V6 V6 makes some sense to me. We have to remember that Jeep actually owned the tooling for the Dauntless Buick 225 V6 V6 for a while before they sold it back to GM during the Iranian oil embargo.

As far the next step in the swap, regardless of the direction you choose, is to list out all of the pieces to the puzzle needed to complete the job. I mean everything including all of the incidentals and consumables. Once the list is made then start the search and acquire everything before you break down the jeep otherwise it may just become another unfinished project gathering dust in the garage waiting for a part.

The other option for power is to look at changing the gear ratio in the pumkins.

 

[mtnwhlr]

 

[cass]

my dad had a 79 CJ5 with a I6. it had tons of torque and ran highway speeds just fine. you could get all the parts and bolt that guy right in, or go one step further and go with a 4.0 fuel injected I6. those motors are everywhere and readily availible.

 

[Gertie The CJ7]

My jeep has the stock AMC 258 i6 / 4.2l inline 6, but I added the MSD Atomic EFI kit and it has more power, starts right up and compensates nicely for altitude change in the Rockies. The kit is very easy to install and program, but did cost $2k new ;-/

 

[Tinman22]

10 grand ......I wonder if I could send my wife a bill and have her cut me a check for all this work? I could make a living working on my own stuff!

 

[mtnwhlr]

You will find that going to a lower gear will help a hole lot and be alot cheaper.