4.0L to Carburetor conversion question

I know people think there is absolutely no reason for doing this and I am not here to stir up that debate. I am just curious if anyone knows what happens (from experience or second hand) to rigs that convert the 4.0 Fuel injected rig to a Carburetor. As I understand it, it is a fairly simply conversion, you just have to replace the intake and exhaust manifolds from an older 4.2 setup, with some modification. I thought it was cool that the engine does not need a new head.

I assume there is some trick to making sure fuel flow is regulated properly but that can be figured out.

My question is: how is engine timing regulated in this case? Would you still need a working MAP sensor connected to the ECU? That can't be because the injectors are all gone. So what controls engine timing. Perhaps I am just unaware of an existing timing chain or belt?

The idea is to downgrade to no computer or sensors. Yes, I know this is a DOWN-grade. Just curious if it would work in theory and if anyone has done this.

I have no plans to do this. Just a flight of fancy.

I will be watching this thread.

Just set up an Offenhauser intake with an HO head on a 4.2 block in a 95/89/87/90 wrangler(its a frankenjeep) with a holley offroad carb. Ran it with a chevy HEI 6cyl distributor. Which in turn will run your tach signal on an older xj

like you said, its super simple
Good luck

What year 4.0? I ask because you'll need to run a manually adjustable distributor to control timing without the ECM (assuming you are getting rid of the computer along with the injection?)
The renix years, I don't know. On my '98, there is a distributor - but it's not adjustable. The distributor has an integrated cam position sensor (if I'm remembering right) that tells the computer when to fire spark & injection and distributes spark at the same time. The 98 style dizzy won't work without the computer.
Renix I think is adjustable still, so it should work just fine being driven off the camshaft (which is driven off the timing chain)
I'd really encourage you to give EFI a chance, since I can't imagine a benefit to carbs, but keep us updated if you go for the carb setup and take pictures.

if you have a renix distributor collar looks like a U with a hole, and you cut the ears off the distributor you can run any stock XJ one and manually set the timing but it will run like garbage.. get the GM HEI one, it has vacuum advance and it will run great

Yup, the XJ distributors had not mechanical or vacuum advance.
But I would think one from a 4.2L would as they were sans electronics.

Vacuum advance gets attached to the port vacuum on the carb.
The engine will start on mechanical advance and transition to vacuum advance at cruise.

The carb will tend to give fits off-camber or on sudden stops as fuel will overspill the bowl and flood the engine. You can offset this a bit by lowering the fuel level in the bowl.

Fuel needs to be regulated to 5-7psi. Any more than the and the pressure will overwhelm the flows needle and flood the engine.

-Ron

Is your intent for SHTF situations? That's the only reason I would imagine you would want to do this...