98 4.0 questions

blueoval · Post by **blueoval** » Wed Jan 05, 2005 3:57 pm

Ok guys, I have some questions! I have read alot about the 4.0 swap on this board and other places. Here is my question - How would a 4.0 out of a 98 explorer work? I know I have read that around 94 is the best donor year due to similar harness routing, etc. Has anyone tried one of the later model engines?

Can I still use my manual trans with this engine? I know the old flywheel is supposed to work with the early 90's 4.0's, but what about these?

Is the 4.0 short block similar enough to use the 2.9's intake, etc.? Would that even be a consideration?

What is this engine worth with 79,000 miles on it?

Thanks for your help!

blueoval · Post by **blueoval** » Wed Jan 05, 2005 3:58 pm

ps - I have posted on here quite a bit in the past, but something happened to my account. Now I see I am back to a recruit.

DBrown · Post by **DBrown** » Wed Jan 05, 2005 4:30 pm

the 90-94 4.0L is th best donar because of a few things......

1. wiring issues and only one O2 sensor
2. they are a direct dolt in to the 2.9L
3. you can use your fly wheel with these years, as long as you match the starter to the selection.

I don't think you can use the flywheel from the 2.9L on the newer 4.0L's they did a big overhaul to the design I think you are talking about.

Is the 4.0 short block similar enough to use the 2.9's intake, etc.? Would that even be a consideration?

from what I hear, no. while they are in the same block family the top ends will not swap.....on top of that if it did you will have a problem setting the timing.....the 4.0L uses a distributerless system and the 2.9L uses a distributer. other bonuses are the 4.0L is MAS air and the 2.9L is not.

I have heard that you can alter the bell housing on the original tranny to fit this motor.......but this is where I dissagree totaly with this swap. your tranny is only rated to hold around 170ft/lbs of torque. while the 90-94 4.0L is around 220 this motor is more then that. so, you are really already pushing your luck with the 90-94. while I had no problems out of mine I also used the 2.9L flywheel for one reason......I would rather replace a clutch then have to rebuild or go threw the hastle I had trying to find a new tranny. if you are planning on doing a motor swap I say go 5.0L but if you are on a budget then the 90-94 4.0L is the one you want. I enjoyed mine alot, and didn't regret it for one minute.....but I was only trying to keep mine on the road untill I could go for the 5.0L. now I have a 351M go figure........if you need any help just post up I will help you with what I know.

blueoval · Post by **blueoval** » Wed Jan 05, 2005 4:44 pm

Thanks for the quick reply. I should have thought about the distributorless ignition before I posted. Guess I was not thinking.

Anyway, it appears I need to do some more research before I jump in too deep. I completely rebuilt my transmission a few years ago, so that is why I am interested in keeping it, but I know there have been some changes to the later 4.0's that might keep me from it.

What is the weight difference between the 4.0 and the 5.0?

Thanks for your help

DBrown · Post by **DBrown** » Wed Jan 05, 2005 5:18 pm

honestly I'm not sure but I would guesstimate about 100-150lbs
it's not much but you can also lighten the 5.0L with aluminum intake, headers, see what I'm getting at? the 5.0L just has so much aftermarket that it is more economical to swap to it. that and if you cam it you dont have to remove the heads to get the lifters out, and the gasket kits for the 4.0L are expencive. the 4.0L or 5.0L in stock form is a great motor for these trucks, they put your powerband and HP/TQ numbers where I think they need to be. having a motor that is overpowered can be a bad thing at a certain point. I kinda got a good laugh when a guy once told me he wanted to put a bumpy cam in his off roader......most of the trail riding I do is at idle unless I am just messing around, and I don't like to be jerked down the trail.

blueoval · Post by **blueoval** » Thu Jan 06, 2005 7:23 am

I agree, most people mess up on cam selection. There is more to it than that "bumpity" sound. It has to be a combination of intake, cam, exhaust, etc. Also, a little compression increase never hurts either. But with todays fuels, that can be to much of a good thing, also.

I guess the ideal would be a 347 stroker with a cam range from idle to 4,000 rpm, aluminum heads and intake (mostly for weight), and geared about 4:56.

But, alas, my budget does not allow for that. Maybe some day!:frown:

I appreciate the input!

DBrown · Post by **DBrown** » Thu Jan 06, 2005 7:36 am

no problem....

I would even stay away from the aluminum heads, I have just heard too many bad stories about over heating issues. if I were setting one up I would probably run the HO that came factory 225HP. then upgrade the upper and lower intakes, get a bigger MAS air meter, better injectors, and like you said pick the cam very carefully......even though the factory cam is a good choice. on top of all that I would run some shorty headers to bring out the bottom end HP and let it go. the best part of that motor is the EFI. I have debated going LP on my 351M to make it better on hills untill I get the 302 junk together but I might end up getting an EFI faster then I thought. I already have a motor I just lack the up grades