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Upgrades

There are some very basic upgrades you can add the to 258 to make it run better. I started by adding a weber 32/36 carb and msd blaster 2f coil. Along with the coil I upgraded to the larger ford tfi cap and rotor. These changes helped a bit but once I added the msd 6a ignition the engine ran ten times better. Before the msd my engine would stall every morning,  run rough and stumble at idle. The msd smoothed out these problems and now she starts and runs every morning even below freezing without stalling. The hp gains are probably minimal but I have noticed better throttle response and slightly quicker acceleration. 8MM spiral wound spark plug wires were added as well. They are actually for a ford 300 6 cyl but fit well. The nice part about the msd ignition is it takes the computer and stock ignition module out of the equation. Without the computer I was able to remove much of the vacuum hoses and emissions junk. The 82/83 and up 258 engine had the pulse air system instead of the AIR system with smog pump. The pulse air system was activated by the computer and vacuum solenoids. Without the computer to open the air valves the system wouldn't work. I do need to pass emissions testing in NJ so to keep the system working I removed the air valves and attached two chrome breathers to the hoses (see the pics). This keeps the pulse air system working all the time and should help during emissions testing. It also made more room in my engine compartment because the pulse air system had two large hoses attached to the air cleaner. Look at the old engine pics as compared to the new ones and you'll see the difference.  A metal valve cover was also added to replace the leaky OEM plastic cover.  Right now I'm slowly gathering parts for the 4.0 head swap. I had the head done (new valve job and welded water jackets) modified stock intake, valve cover, and 4.0 exhaust manifold ready to go. I'm just working on getting some small parts and minor details worked out and then its go time. This should produce up to 40 hp or more if I decide to go with a bigger carb or some type of EFI.

Here are some links to info on computer controlled 258 engines and the 4.0 head swap.

http://home.sprynet.com/~dale02/control.htm

http://home.sprynet.com/~dale02/home.htm 

http://monsterslayer.com/jeep/40Head/40Head.htm 

http://www.off-road.com/jeep/new/40conv.html

This diagram shows you how to wire the msd ignition and bypass the computer.