4.0 head and EFI on a 4.2 block

[rayzr]

.030, .050 and .060. No Go.
I'm in the driveway, working on it as we speak!

Thanks,
Ray

[Jeep-Power]

bummer.

Are you certain that you have the distributor correctly indexed?

Have you called HESCO?

[rayzr]

Yes, I've been on the phone with Bennie. We are not getting any spark out of the dizzy. I reindexed the dizzy, and cut off the ears to get everything fine tuned when we get it running. But first, I need to get spark!

I even reset the CPS to .030 per Bennie.

Thanks,
Ray

[Jeep-Power]

The coil - I know you said you have power to it. Is it good?

I don't have my FSM here at work...

[rayzr]

It tested good, per the FSM specs.

Ray

[Jeep-Power]

Ray-- how are you doin' with the Jeep?

[rayzr]

Peter,
I am doing good. The no start problem was a broken conductor in the cable that connected to the CPS. I metered everything out and replaced the cable.
I cranked the engine and it backfired out the TB so I knew I was out 180. Pulled the dizzy and reset it, and it fired up! This 258 MPFI runs awsome! I'm taking it over to the Pinelands for our "Scout the Pinelands" trip, next weekend. For now, I'm running local to get everything broke in.
And just a FYI, it is in a 1974 International Scout II.
I want to thank all who replied to my post for help.

Ray

[Jeep-Power]

awesome.

Sorry about that-- I ASSumed...

enjoy!

[DirtyB]

"raises the compression ratio to something like 10:1. Higher compression means more throttle response and TORQU"

I've searched the forums and can't see where anyone needs to run higher octane gas because of the increased compression ration? I'd like to put a 4.0 head and fuel injection on my '81 scrambler, but I don't want to be stuck with real expensive gas.

[Pedestrian]

New to the Jeep thing, can I use a 92-94 Jeep Grand Cherokee 4.0 4x4 as a donor for this conversion?

[Zorm]

yep, grab the fi also and enjoy

[Jeep-Power]

yep, grab the fi also and enjoy

x2

[Zorm]

adding a 4.0 head to the 258 does not require the higher octane fuel. I had mine on for at least two years, not a tone of driving but I did drive it from San Diego to Pensacola, Fl with no issues and using reqular unleaded all the way. Now, I did not have the FI but I did have the 2100 carb, 258 intake and a HEI dizzy and loved the umph I got. Right now I'm building a 4.6 stroker with 30 over pistons, we'll see how the ole 83 Cherokee 4dr does with that.

[Jeep-Power]

adding a 4.0 head to the 258 does not require the higher octane fuel. I had mine on for at least two years, not a tone of driving but I did drive it from San Diego to Pensacola, Fl with no issues and using reqular unleaded all the way. Now, I did not have the FI but I did have the 2100 carb, 258 intake and a HEI dizzy and loved the umph I got. Right now I'm building a 4.6 stroker with 30 over pistons, we'll see how the ole 83 Cherokee 4dr does with that.

mine ran fine with 87, as well. Under heavy load (long interstate hills with the 34's on) the 92 octane made a noticeable difference. No pinging & more power. I'd just fill it with 92 before getting on the interstate. Otherwise, it was 87 around town.

good luck on the engine build!

[n_stockstill]

Wow what a great article and some amazing contributors. Im fairly new to the jeep world. I bought an 83 cj5 with the 258. I dove in head first and put new axles under it (dana 60/44). I stretched the frame front and back and extended the wheelbase 19". 9 forward, and 10" back. Hummer wheels with 36X12.50. Now I've not got my new drivelines built yet BUT im anticipating some lack of power. The gear ratio was pretty well doubled but was a little doggy to begin with. I may still have to regear yet. The main reason for posting is I am planning on the 4.0 EFI head swap. It may be a while yet before I get the money scraped together to tackle the project. The previous owner had removed the factory "computer controlled" carb and replaced with a motorcraft carb which performed pretty reliably. Short story long, im concerned some of the wiring that was factory may have been removed. Maybe wrong but just wondering how to tell? Don't know what this thing looked like stock. Any thoughts, ideas will be greatly appreciated. Thank you everyone in advance. GREAT, GREAT article!