will the 2.8/2.9 distributor work on a 4.0L

[MAKG]

That would be a problem! Making a lower intake would SUCK. It could be done though.

Which is exactly what I was discussing. The upper intake -- while still very challenging -- is considerably simpler geometrically. The lower intake is either going to flow well on a flow bench or be driveable, if made by guessing.

And do you have any way to back up your claim that your sheetmetal intake outperforms ANY intake? I severely doubt it.

Putting three carbs (much less space than one or two) adapted to the lower intake can't make much improvement in space. The upper intake by itself isn't all that high, and now you have to squeeze in three throttle bodies with synchronization, plus a set of venturies plus float bowls plus fuel plumbing plus air filters.

 

[AllanD]

You can try all the work arounds but the simple and direct approach is just do the wiring work and replace athat 2.9 with a 4.0 and run the stock 4.0 injection.

People have done it. I have done it.... twice

Though there ware radical differences in complexity on the two I've done.

The EASY one was replacing a 1991 2.9 with a 1992 4.0.
that swap was no more difficult than replacing a 2.9 with
another 2.9, except the wiring harness, computer radiator hoses
were swapped with the engine.

The HARD one was swapping a 1993 Explorer engine into my 87 supercab.
Forward of the firewall grommet it's 93 behind the dash it's all 87.

The second swap took me about a month of actual work.

The 91/91 swap was started with a running truck on a friday afternoon
(about 1pm) and resulted in a running truck by sundown Sunday.

It's all in the preparation, both mental and material.

Other than the fact that carbs often don't work and can't easily be diagnosed
and in general can be described (philosophically) as a device that under any given circumstances delivers the WRONG ammount of fuel, the legal wrinkle that they are ILLEGAL on a truck originally injected, and as a side note will NEVER work as well as EFI when doing "angles and dangles" offroad I can't imagine why anyone would want carbs.


AD

 

[almostclueless]

OK....to answer the OP's question;


I"ve never compared any of these dizzys. Someone posted that the 4.0 stub and the 2.9 dizzy compare from where the hold down holds them downward.

Someone else stated they believe the dizzy runs the opposite direction in the 2.9 and 4.0.


You said you have a good bit of resources to fab something up, and I understand why you want to.


Furthermore, if you succeed in carbureting a 4.0, your accounts of this may help someone else here. With that in mind;


Why don't you pull the dizzy out of the 2.8, get a 2.9 dizzy AND a stub for a 4.0 OHV, and start comparing them all. According to what Ive read elsewhere, at least the deck height of the 2.8 and 2.9 are the same.

And so what if the 2.9/4.0 run "backwards"? With a TIG, the mounting for the vacuum can could be reversed, and the gear from a 2.9 could be swapped onto a 2.8 dizzy at the correct height (so long as the shaft is the same diameter, length, and the hex for the oil pump drive is the same).


It wouldn't shock me one bit if the 2.8 dizzy has the same dimensions below where it clamps down. So to rehash the factors that matter;


1. Dimensions of the dizzy body "below the clamp"
2. Direction shaft turns
3. Shaft diameter
4. Oil pump drive size



And when it's all said and done, the TFI dizzy in a 4.0 could send a signal to an aftermarket timing computer anyway. This is NOT an impossible task, it just requires a little extra effort.


If you feel like being an explorer here, I say give it a shot!!

 

[almostclueless]

And BTW......I bet if someone who reads TRS and has Sven Pruett's book looks, I bet he's already looked at this stuff.

 

[DPDISXR4Ti]

The 4.0 camshaft does indeed have a cam drive 'gear' on the back, just like the 2.9 and the 4.0 uses a blank oil pump drive, driven off the cam gear to rotate the oil pump. The 2.9 has this exact same setup to rotate the oil pump AND the distributor shaft. These setups are basically identical (see picture below - 2.9 distributor on the left, 4.0 oil pump drive on the right.) I have installed a 2.9 distributor on a 4.0 on an engine stand, rotated the engine and verified that everything works properly.

Bumping this thread from the dead! Below is a 2.9 distributor and a OHV 4L oil pump drive "plug". I'm trying to do the opposite of what is suggested in this thread - I want to run the 4L part in the 2.9 as part of a conversion to distributor-less using EDIS. However, the 4L plug doesn't seem to go all the way into the 2.9 block - it stops about 3/8" short of the bottom. Everything seems to measure out the same, just as "Bird" suggested back in 2008.

What am I missing???

 

[alwaysFlOoReD]

Is the hole in the bottom of the shaft the same distance in depth? Where the oil pump shaft goes.

 

[bobbywalter]

yeah.....did you ever check the backset ??.......the pictures missing from page one are the ones you provided....that is cool.


there is no reason to run the stub regardless....just run the non cam sensor pcm that matches that stub. leave the dizzy there.

 

[DPDISXR4Ti]

Is the hole in the bottom of the shaft the same distance in depth? Where the oil pump shaft goes.

Everything I've measured in that regard seems to be the same.

 

[DPDISXR4Ti]

there is no reason to run the stub regardless....just run the non cam sensor pcm that matches that stub. leave the dizzy there.

I realize that I could just leave the distributor in there, but I'd prefer to make things as un-cluttered as possible. I also may very well want to locate the coil-pack in that air-space similar to how it's done on the 4L.

 

[alwaysFlOoReD]

I remember on one engine, not sure what size maybe 460, the oil pump drive has a press fit washer on it. I'm not sure if that washer is supposed to be up or down facing, but if up I wonder if that is keeping things from bottoming out.

 

[bobbywalter]

i have had several 8 and 6 cyl remans that were bottoming out on the pump or the drive rod and needed clearance which i did with a flap wheel.....couple of 460,s in a row...put paint on it...we suspected it was the hv aftermarket pump.

this assumes the 2.9 dizzy drops right in the 4.0 no issues.

 

[DPDISXR4Ti]

I can now confirm that a 2.9 distributor fits just fine into a 4L block with cam installed. Distributor rotor spins just fine when cam is rotated.

 

[DPDISXR4Ti]

I'm wanting to grab another "dummy plug/oil pump drive" and/or cam position sensor/oil pump drive plug on my next junkyard visit. I know on the 2.9 the fastening bolt for the distributor is a 13mm head - is the 4.0 the same? I know for the 2.9 a distributor wrench makes the job easier. I'm guessing on the 4L access is straight on and nothing fancy needed - yes, no, maybe?

 

[rusty ol ranger]

I'm wanting to grab another "dummy plug/oil pump drive" and/or cam position sensor/oil pump drive plug on my next junkyard visit. I know on the 2.9 the fastening bolt for the distributor is a 13mm head - is the 4.0 the same? I know for the 2.9 a distributor wrench makes the job easier. I'm guessing on the 4L access is straight on and nothing fancy needed - yes, no, maybe?

Even the V8's are 13mm/1/2 inch. I would assume they are pretty standard across the board.

Pretty cool it worked though.

But just to add one little tidbit though a 2.8 distributor wont work in a 2.9 and therefore wouldnt work in a 4.0

 

[DPDISXR4Ti]

Even the V8's are 13mm/1/2 inch. I would assume they are pretty standard across the board.

Pretty cool it worked though.

Thanks for the confirmation on the 13mm hex head. I couldn't figure out which bolt it was in my can of fasteners from the 4.0 I dismantled.

I should point out from my photo above, I didn't get anything to "work" - I merely dropped the 2.9 distributor into the hole typically occupied by the "dummy plug" on the 4L. Heck, I don't even know if it might fight for space with the intake manifold or something on a fully assembled engine.