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Fuel injection for 4.2

13K views 6 replies 3 participants last post by  B.LaBrier 
#1 ·
I've been reading through alot of the stuff for converting to the fuel injection, I know that there are several different kits that i can buy to do it but there out of my price range at the moment. I've also seen just swapping the injection parts from a 4.0. My dad mentioned something about swapping parts from a Chevy 4.3? I haven't been able to find anything about this swap though. Does anyone have any idea on this one? I'm more inclined to do the 4.0 injection swap because we have the 4.0 head on our 4.2 block already. But he's persist on the chevy 4.3 injection parts swap. Does anyone have any input on this?
 
#2 ·
I've been debating doing my own chevy 4.3l tbi efi swap on my engine for the past few months. I was planning on going with the megasquirt setup along with all the 4.3l tbi parts. I'm comfortable in my ability to try it, just haven't had the time to get around to doing it. Here are a few helpful links I've found

BustedJeep.Com - In The Garage

Fuel Injection
 
#3 ·
The Chevy 4.3L TBI swap is a popular "junkyard" version of the Howell TBI kit. BOth use the exact same throttle body and computer, but Howell has a pared down harness and doesn't use a knock sensor to adjust timing, essentially making the Howell kit more like a hybrid fuel injection setup - precise fuel delivery of fuel injection, but still old school without electronic spark control. Do a search for "Jeep junkyard TBI swap". Jeepforum has some good info and writeups.

If you already have a 4.0L head, you are already on your way to a MPFI swap. It'll be a bit more labor intensive though, and will require a new harmonic balancer. One thing to be aware of about putting MPFI on a 4.2L engine is that if the engine is worn, you are more likely to get engine ping, resulting in need for higher octane fuel. Mopar warns about this potential problem regarding their MPFI kit.

The most cost effective solution to convert the 4.2L to fuel injection would be the junkyard 4.3L TBI swap. I have the Howell kit, and even though it's TBI, it is leaps and bounds better than the stock carb setup.
 
#4 ·
The Chevy 4.3L TBI swap is a popular "junkyard" version of the Howell TBI kit. BOth use the exact same throttle body and computer, but Howell has a pared down harness and doesn't use a knock sensor to adjust timing, essentially making the Howell kit more like a hybrid fuel injection setup - precise fuel delivery of fuel injection, but still old school without electronic spark control. Do a search for "Jeep junkyard TBI swap". Jeepforum has some good info and writeups.

If you already have a 4.0L head, you are already on your way to a MPFI swap. It'll be a bit more labor intensive though, and will require a new harmonic balancer. One thing to be aware of about putting MPFI on a 4.2L engine is that if the engine is worn, you are more likely to get engine ping, resulting in need for higher octane fuel. Mopar warns about this potential problem regarding their MPFI kit.

The most cost effective solution to convert the 4.2L to fuel injection would be the junkyard 4.3L TBI swap. I have the Howell kit, and even though it's TBI, it is leaps and bounds better than the stock carb setup.
The pinging with the 4.2l and mopar mpfi only happens with the stock 4.2l head. A swap to the 4.0l head usually prevents pinging, and since he already has the 4.0l head he'll be great. The mopar mpfi is a much more efficient swap over the 4.3l tbi setup since the mpfi controls timing and a few other systems. It's a toss up on what ever can be found for cheaper really
 
#5 ·
I don't know how I forgot that OP already has the 4.0L head. DOH! :facepalm:

As far as the "junkyard" 4.3L TBI swap, if I recall correctly it does have electronic spark control built into the system. That is the benefit of going with the junkyard conversion over getting the Howell kit (where allowed).
 
#6 ·
As far as the "junkyard" 4.3L TBI swap, if I recall correctly it does have electronic spark control built into the system. That is the benefit of going with the junkyard conversion over getting the Howell kit (where allowed).
It does have spark control. The spark curve for the chevy engine verses the jeep engine is different and requires a type of controller when you swap. The mpfi is optimized for the jeep engine already and requires less electric work. That's why Howell omits the spark control
 
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