4.0 cam in a 2.9?

[Beleneagle]

Has anyone tried a 4.0 cam in a 2.9? I know that the push rods are shorter due to the roller cam, and the distributor gear will need to be changed. Are the cam bearings the same size? Is the cam retention the same, or is the roller cam have a different retainer? I was just thinking since 2.9 cams are hard to come by this might be a good replacement.





David

 

[Beleneagle]

Alright, does anyone know if the cam journal sizes are the same between the two motors, or am I better off just calling a machine shop?

 

[disciplerocks]

I think you should be the guinea pig. 2.9 and 4.0 share the same block and I know Copykat discovered the exhaust mounts are the same. Haven't heard anything on internals though.

 

[Beleneagle]

I'll see what I can find out, but it will be a while. I check with a machine shop in a week or two. My 2.9 is still going, and there's a 4.0 in the garage just waiting till late spring Lord willing.



David

 

[disciplerocks]

I would think the distributor would give you some trouble, but I'd be interested in seeing results.

 

[Beleneagle]

I think it's just a matter of swapping the gear over from the cam sensor. It lives in the same hole in the block where a distributor use to go. As long as the shaft dia. is the same, I don't see it as a problem. I'm much more concerned about the cam plate and what keeps the roller lifters from turning (rotating in the bore) on a 4.0?




David

 

[holyford86]

I think it's just a matter of swapping the gear over from the cam sensor. It lives in the same hole in the block where a distributor use to go. As long as the shaft dia. is the same, I don't see it as a problem. I'm much more concerned about the cam plate and what keeps the roller lifters from turning (rotating in the bore) on a 4.0?




David

The lifters in a 4.0 fit into a keyway to keep them from turning in the lifter bore. One time I dropped a 2.9 distributor into a 4.0,you could turn the motor over and there was no binding. To the naked eye the oil pump drive gear and the 2.9 distributor look the same, I didn't measure them though.

 

[Beleneagle]

When you dropped the distributor in the 4.0, what year of 4.0 was it? Did it have the plastic intake or the aluminum one?




David

 

[holyford86]

1995 motor with the composite intake, the upper intake plenum was removed at the time, the engine was on a stand as well. The distributor will not clear the plenum, tried it.

 

[Beleneagle]

I'm wondering if it might clear the earlier aluminum intake......

 

[holyford86]

I'm wondering if it might clear the earlier aluminum intake......

Probably not, they have more meat back there

 

[AllanD]

I think you should be the guinea pig. 2.9 and 4.0 share the same block and I know Copykat discovered the exhaust mounts are the same. Haven't heard anything on internals though.

Uhhh... No, they are NOT the same block.

The 4.0 block is wider across the pan rails to clear the crankshaft counterweights and the block decks are taller (relative to the crankshaft centerline) by 20mm (about 8/10th of an inch) to accomodate the greater STROKE of the 4.0.

The engines share the bellhousing pattern and crankshaft bolt flange (up to mid 1997 anyway) but thats about as far as it goes.

Many posts about or asking questions about modifying a 2.9 engine share a common theme... people trying to avoid the relatively easier path of simply swapping in a 4.0,

Some of the engine mods suggested could theoretically could be done,
but it wouldn't be too out of line for some of the more complex ones
to pack the specially modified parts in crumpled $20 bills to ship them
back to the customer...

Frankly i Think if you REALLY want a roller cam in your 2.9 you should swap the 4.0 BLOCK "into" your 2.9 at the same time.

I think you should be the guinea pig. 2.9 and 4.0 share the same block and I know Copykat discovered the exhaust mounts are the same. Haven't heard anything on internals though.

No he didn't "discover" the fact that the 2.9 Y-pipe will bolt directly to a 4.0
or that a 4.0 from a TTB truck (either 1990-97 Ranger or 1991-94 Explorer)
uses the same mounts because I've personally said exactly that
Oh... probably 250times in the last five or six years.

So "Re-discovered" is a far better word.

Swapping to a 4.0 from a 2.9 isn't rocket science.

what is difficult about it is all the subtle variations in BOTH the engine donors and the (formerly) 2.9 engine receipients make explaing the swap in a single post all but impossible.

And the fact that some swaps (like any swap into a Gen1) is far more electrically intensive than a swap into a Gen2 or Gen3.

My personal truck, an '87 was about as difficult as a 4.0swap gets
on a receipient that atleast already has an EFI fuel system

On a Gen2 you just need to get the COMPLETE engine bay wiring harness
from a RANGER. Sure a 1991-92 Explorer harness CAN be made to work, but
you need to have the EVTM for BOTH vehicles to figuire it out...

"dash swaps" are NOT an easy way out on a Gen1, it just changes which tribe of gremlins you are gonna do battle with...

Personally I think the 4.0 is the engine that should have been in Rangers from the very beginning. The 4.0SOHC was "an improvement too far" as it created a piggish monster with serious longevity and maintainance issues (That "Rube Goldberg" timing chain system)

Switching to a 4.0 myself for a daily driver has made me realize in just how
many ways I really wasn't happy with the 2.9.



AD

 

[Beleneagle]

Some of the engine mods suggested could theoretically could be done,
but it wouldn't be too out of line for some of the more complex ones
to pack the specially modified parts in crumpled $20 bills to ship them
back to the customer...

Frankly i Think if you REALLY want a roller cam in your 2.9 you should swap the 4.0 BLOCK "into" your 2.9 at the same time.
AD

That is my plan, as I have a 98 4.0 sitting on a stand in the garage. I'm planning on doing the swap next April or May if all goes well. I however was curious about the cam swap, because I hadn't seen it mentioned before.

Should I swap a earlier intake (Like a 91'/92') on my 4.0 to make the swap easier? It came out of a 98' Explorer, and while the engine is complete, I will have to get the rest of the stuff needed for the swap from the boneyard.


David

 

[dirtymike]

Isnt the 4.0 a bored and stroked 2.9

 

[holyford86]

Isnt the 4.0 a bored and stroked 2.9

"technically" it is but it also has a widened block and a raised deck height to accommodate the larger crank