Carburated 4.0 - Whats required?

281 quadcam

Lets say one had a CJ in need, low cash, and happened upon a 4.0 Long block. (complete minus intake, and accessories) What else needs to be done to get this thing to run carburated? I obviously have to ask about the fuel pump. In tank is ready for it, but can you run the stock 4.0 fuel pump, or do you/can you put a 258 pump on it? Distributor.. Does that need to be replaced or modified, with what or how? Intake, a 258 intake will go on? Less obviously, how do i get things like temperature reading to work again, and is there anything in the engine that requires the ECU? The thermostat will still open without ECU control, right? This is going into an otherwise stock '79 CJ5 drivetrain, does that bring any special concerns? Stock '79 bellhousing, right? What pilot bushing gets a T150 input into a 4.0 crank? Stock CJ one?

ol' school power

You need a stock 258 distributor. The 258 intake doesn't match up correctly to the ports of a 4.0. The in tank pump is capable of pushing 80 psi. A conventional carb requires 4.5~6psi. You either need another pump or to add a regulator capable of dealing with the pressure.

Mudrat

ol' school power wrote
You need a stock 258 distributor.
The 258 intake doesn't match up correctly to the ports of a 4.0.
The in tank pump is capable of pushing 80 psi. A conventional carb requires 4.5_6psi. You either need another pump or to add a regulator capable of dealing with the pressure.

Yup ... bit I would drop an HEI setup on it, upgrade the in/out and a good pressure regulator. I might add if your going carborated, look to something more modern than the BBD :oops: You can get the Weber 36 or adapt a 2100 and it will do wonders for your breathing!!

Mudrat

Lifted79CJ7

I can vouch for the MC2100 carb, I had one on my 304 and that thing would run at any angle. Jack

ol' school power

the 2100 is a good carb. I ran them on 258's almost 20 years back.