4.0 head and EFI on a 4.2 block

Post by **cerusmc21** » August 12th, 2008, 2:51 pm

found the problem. the cps sensor was the wrong one, or bad. the magnet in it was strong enough to pick up a 3/4 in. wrench!!! put a new one in and she pures like a kitten...ok, more like a lion on crack, until i got the exhaust done up.

wow, what an upgrade. can wait to see how she does on the trails.
Thanks a lot for all the help. this write up is great.

Post by **Jeep-Power** » August 27th, 2008, 8:46 am

Sorry I missed al the action here-- I need to check my settings and figure out why I'm not getting email notifications.

Cerusmc21-- I'm stoked to hear you got it all figured out!!

yeah-- it may not give you all the power of a stroker (I don't know that for sure yet

) , but it sure wakes up the old 258!

Post by **Jeep-Power** » September 2nd, 2008, 4:09 pm

Dyno appointment at 11 am tomorrow!

Post by **Jeep-Power** » September 3rd, 2008, 6:31 pm

Dynoed it today on a chassis dyno-- a Dynojet.

Readings were at the wheels:

117 HP at 3700 RPM

190 Ft Lbs of tourque from 1800RPM thru 2600 RPM

Post by **eliv1** » September 4th, 2008, 12:48 am

Peter,

what cam are you running? 4.2L?

Post by **SilverXJ** » September 4th, 2008, 8:16 am

Do you have a before dyno as well?

Post by **Jeep-Power** » September 4th, 2008, 8:27 am

It is the stock '84 258 cam.

no, I did not dyno it before...

here is the sheet:

It shows tow different 'pulls' the green one being the first. The second pull had some sort of timing hiccup at 3000RPM and then the A/F ratio plummets after 3500 RPM. The second run we were shooting for 4000RPM, but it seemed to hit the rev limiter or something. The A/F shows it going way lean.

Post by **manicjester3** » November 21st, 2008, 8:46 am

I was thinking about doing this to my 258 in my 1979 J 10. I was wondering if I could use an intake and injectors from a 99? If I do, what do i do about the fuel pressure regulator? Is there a stock fuel pressure regulator?

Post by **Jeep-Power** » November 21st, 2008, 9:28 am

manicjester3 wrote:I was thinking about doing this to my 258 in my 1979 J 10. I was wondering if I could use an intake and injectors from a 99? If I do, what do i do about the fuel pressure regulator? Is there a stock fuel pressure regulator?

You can certainly use the '99 setup. The fuel pressure regulator was located somewhere twards the rear of the vehicle-- near or in the fuel tank (??) . I'm not sure of it's wherabouts exactly. From what I've heard on Strokers, this was done to keep warm fuel, returning from the engine compartment, out of the tank.

You can certainly use the '99 intake and injectors with an earlier fuel rail.

Post by **EFIeagle** » July 10th, 2009, 2:18 am

Do you have any pictures of how the dark blue wires are spliced? Do they go directly to switched source or are they just joined in, and continue through teh harness? I'm currently putting a junkyard EFI setup on mine...

Post by **Jeep-Power** » July 10th, 2009, 7:56 am

EFIeagle wrote:Do you have any pictures of how the dark blue wires are spliced? Do they go directly to switched source or are they just joined in, and continue through the harness? I'm currently putting a junkyard EFI setup on mine...

no photos-- I'm pretty sure we connected it to the manifold heater circuit, as it was right there on the firewall and not being used anymore. All it has to be is a switched positive source. We chose one that came off the factory wiring harness that was fused and the same size (gauge) wire.

Post by **onlyridinyamahas** » August 4th, 2009, 6:59 pm

Hey Im currently having an issue after replacing my harness. My ears had to be cut to originally get it going but it was great until some coolant burned up my harness. Now I cant get my timing back how it was. Iv indexed it aa billion times. Was the number on ur crank set to exactly 0 at TDC. I got a 4.6 the cam is 300 lift 300 duration... I had to turn my distributer about one terminal clockwise to line it up originally. Thanks! <number removed>.

Post by **Jeep-Power** » August 5th, 2009, 10:07 am

coolant burned your harness? How does it do that-- it's about half water?

I'm sure you are not talking about cutting the ears off of your own head, please elaborate...

Post by **amcinstaller** » August 5th, 2009, 9:36 pm

hmmmmmm.......must like wierdos calling him to post up a phone number.....

Post by **Jim** » November 3rd, 2009, 3:56 pm

Hello to all .I just joined the sight today. Since I am all carbed out this is exactly what my 89 YJ needs, before I start buying the parts off your list I have two questions: #1- If the block is not bored .030 over will this be a problem? #2- It's been almost 2 years since the swap. Now that it is done do you wish you would have done or put something different (Parts) in? Thanks

4.0 head and EFI on a 4.2 block

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