Motor mount bracket/frame horns.

[Andre LeMoine]

Good evening everyone. Finally getting around to doing an engine swap on my '85 CJ7 . I acquired a AMC 258 i6 / 4.2l from a '77 J10 to rebuild and replace the stock Jeep 2.5l. Can someone steer me in the right direction as to which motor mount brackets I need to mount to the frame. Looks like from what I can tell the I6 mounts on the block are about 3'' farther forward than the 4 cylinder. I can see that the bump stop for the front axle will have to come off the frame. Has anyone done this swap on the late model CJ7 ? Right now I plan on keeping the stock T-4 Transmission if I can until I decide on heavy duty 4 speed or ax15. Thanks in advance for the help. Andre.

 

[IOPort51]

Jeep Motor Mount for CJ-5, CJ-7, CJ-8 with AMC 6 CYL.Engines from Mountain Off-Road (M.O.R.E.)


If I were going through everything you are I would go with something like this.

 

[Jimbos76cj]

Andre you need motor moutns for a 6 cyl CJ. The ones IO listed will work great but are pricey. You should be able to pick up a set of CJ stock 6cyl mounts for less then 100 shipped. When i get a chance to go into the shop tomorrow Ill see if I have a set. Once you get the right frame mounts you will need to find out from some one what blot holes they need to go into. As for the bump stop I wouldnt think that it needs to be moved.

 

[Andre LeMoine]

Thanks, the Mountain Off Road mounts are nice, and yes pricey. Let me know what you find on the frame mounts. Thanks for the good info. Block, crank, and cyl head go to the machine shop tomorrow.

 

[yellow85cj]

About keeping the T-4 . The spline counts on the 2.5 T-4 and the AMC 258 i6 / 4.2l T-4 input shafts are different. You are going to have to swap input shafts, or get a clutch with the proper spine count.

The engine (frame side) mounts for a 6 bolt up fine, make sure you got the engine side brackets. No mods to the bump stops as previously stated. Motor mounts are different from the 4, but you would want new ones anyway and they are cheap, under $10 for a set.

Skid plate moves to different mounting holes for the 6.

Drive shafts need to be lengthened/shortened.

Might want to make the Transmission decision now so you don't have to do things twice (clutch, driveshafts, skid).

Here are the AMC 258 i6 / 4.2l frame side mounts on a frame that had a 2.5.

 

[Andre LeMoine]

Wow, thanks for the photo. There is a lot of information in that image. Yes, I have to say when I get the engine together and ready to install I need to have the Transmission ready to go at the same time. Too much work not to do it then. I will also be doing the one piece rear axles for my AMC20 . I have a T19 in my IH Scout 800 that I really like so I will need to decide on a Ford T-18 conversion or maybe the AX15. Five gears would be nice but I would probably never break the T-18 . Thank you for all the responses and will try to post progress once things get rolling. Photo in my avatar is when I got the Jeep. These two photos are a year old. Still looks almost this good. Seats are leather from a late '80s Saab 900. Easy install in a CJ7 .

 

[CJim7]

You are also going to need a bell housing (AMC 258 i6 / 4.2l to T-4 /5). the 2.5 bell wont mount up to the AMC 258 i6 / 4.2l .
As was said, new input shaft or clutch.....but I recommend the new shaft- 10 spline vs. 14 spline. There is a strength difference which is apparent when you compare them side by side. Also, once you swap inputs, you will be able to convert to other (stronger) trannies more easily because you will already have the proper clutch .

When I swapped out the 2.5 for the AMC 258 i6 / 4.2l , I attached the motor to the tranny, and then adjusted the whole drivetrain to where it needed to be. It was obvious by sight which frame holes I needed to use.
The AMC 258 i6 / 4.2l is a long engine....the back of the valve cover will be nearly butted to the firewall, and the fan clearance with the radiator is minute, which brings me to my next issue:
You need the radiator with the offset cap. The older style (centered cap) radiators that were used in front of AMC 258 i6 / 4.2l 's in older jeeps weren't dealing with a clutch fan and they are deeper than the newer style. The clutch fan will contact the older style radiator. I found this out the hard way.

You will also have to alter your tranny tunnel cover. I remember having to cut the holes out more for the difference in location of the tranny/xfercase. When I swapped to a T-18 , I had to trash the old cover and build a new one...there wasn't much left to cut up...lol.

Exhaust, drivelines, fuel linkage cable, there is a handful of things that need attention

 

[Andre LeMoine]

Thanks. Looks like I will probably tackle a Transmission also since I'm not in a hurry to do the swap. Time is on my side. Need to decide between 4 and 5 speed. Been reading the knowledge base on Novak's website to try and help with picking the right components. Pricey adapters but I'm sure well worth it. Leaning towards the T-18 but found a used AX15 with noisy 4th gear and external cluch slave setup for three bills nearby.

 

[Jimbos76cj]

Hey Im an idiot.. I forgot all about this post. If you still need a stock set of mounts I have them.

 

[Andre LeMoine]

Yes I do. No hurry, this is going to take awhile anyway. Got lots of stuff to round up and decisions to make. Thanks, Andre.