Jeep 4.0 multi-port intake, will it fit a 258?

Specifications, applications, part numbers, and prices for various OEM fuel injection components.
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Hans
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Jeep 4.0 multi-port intake, will it fit a 258?

Post by Hans »

I am wondering about this. I know that people are using their stock 258 manifolds when they do a 4.0 head swap. Does the 4.0 manfold fit on the 258?

I am trying to figure out exactly what was changed when they went to the high-port 4.0 heads. It almost appears that they left the intake bolt pattern the same, only higher on the head. Then the portion to bolt to the exhaust manfiold was raised to match. Correct? or incorrect?

-Hans
Hans
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Post by Hans »

Wow, took me forever to find a picture that showed the point I needed to see. It appears that yes it will, but new holes will need to be drilled for 2 support pins. These holes need to go in the webbing underneath cylinders 1/2 and 5/6.

Hmmmm... I might have to grab one off of e-bay and try it.

-Hans
miked
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Post by miked »

might try the IFSJA.org site, ~joe is pretty up on the 258 I believe
hippled

Post by hippled »

Hello Hans
I am doing this as we speak. I have mounted a 1991 4.0L intake manifold to my 4.2L 1990 head. Yes you do need drill the two mounting pins hight and have to cut out some of the webbing that goes in between the intake port to make room for your 4.2L exhaust manifold. I had to also modify my power steering pump as well. I also needed to get a EFI air filter setup and trottle cable, but other then those it is not to bad to do the switch. I have not yet started my jeep. I have everything done(fuel lines and pumps, wiring, ignition) that only thing left to get me started is I need make/buy a new gas tank skid plate and a figure out a few IAC problems posted here viewtopic.php?t=19535. I am running MSII on a V2.2 board running 2.36 code controlling a HEI 7 pin ignition module for spark.

Dave
diegom6
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Post by diegom6 »

Assure to get a H.O. head version of 1991 & UP, they are revised and updated and flow whole better than any 258 head and earlier (1987-1990) non H.O. 4.0L engines.

Both are interchangable. 1991 manifold up to 1999 if memory serve me fine it's better also and will match H.O. head, non H.O. head will have some trouble making fit it.
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mattscot007
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What year Jeep?

Post by mattscot007 »

It depends what year Jeep you have. 1981 and newer 258 jeeps have a non-mated manifold setup and are direct swaps for the EFI manifolds. 1980 and earlier applications need to pick up a later exhaust manifold from the junk yard.

I fuel injected my 1980 CJ-7 about 8 years ago with a MOPAR SEFI kit (before I had heard of MS). The kit uses parts off of a stock '95 wrangler, with only the computer being rechipped. The later distributor is a direct swap. The kit came with a hall sensor to mount on the on the oil pan, triggered off of the harmonic balancer (added a magnet to balancer if I remember correctly). You shouldn't have much trouble with this swap.

A few things I learned. My year CJ had the exhaust running on the driver side, while the wrangler has the exhaust on the passenger side. The wrangler setup is for the fuel line on the driver side, so that is where I ran the new fuel line. I ended up having problems vapor locking the frame mounted fuel pump. Keep the fuel on the passenger rail if possible, or make a heat shield (maybe even 2 layers thick separated by 1/2 inch [trust me, I'm a Mechanical Engineer and the second layer makes a HUGE difference]).

I had detonation problems with my setup BIG TIME... It didn't act like it ran lean... but maybe MS will be better with this... I would suggest ignition control and retarding it a little more up top than MOPAR did in there kit.

Good luck
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