I`v modified a lot of motors from .10cu. nitro burning model engines to 900+ cu. diesel`s. Now it`s time for my 4.0L Cherokee engine. I want to get the most power I can but still keeping it very street worthy, as in driveable. Back a few years ago Hot Rod Magizine did a piece with Lee Hurley from Hesco engines on a 4.0L Jeep Camanchee. They used a 258 AMC crank custom over bore pistons, a solid lifter cam and adjustable push rods everything else was stock. What this combination makes is a 4.7L engine. With the help of a Paxton super charger they achieved over 300HP. If any of you have ever driven a vehicle with a 258 AMC engine you know they are not real power houses but they do have a good supply of bottom end torque.The 4.0L Jeep engine is geared more towards the higher rpm`s, So why not combine them and have the best of bolth worlds. What really sold me on this combination was when I drove my uncle`s YJ with a fuel injection kit installed on it, I could not beleive the bottom end power it had, the only problem was it only lasted to about 3000 rpm. But after driving that rig I just had to have that kind of power but I wanted to have it all the way to 5000rpm`s.

I decided to call Hesco engines and see what they had to say. Bennie at Hesco engines said they had a complete kit including the crank, pistons already pressed on polished rods, rings and bearings and that it would have the power combination I was looking for. So I couldn`t pass it up and had him send it to me. While talking with Bennie I asked him if there was anything else I needed to consider with the added cubic inches. He told me that the cylinder head on the 4.0L had plenty of flow to handle the additional size. But I wanted to get the most power I could and after a lot of calling around I decided to go with small block Chevy valvetrain because of the the high cost of performance Jeep parts. So I went to AC Nutter racing engines and asked him if he could put in a complete Chevy valve assembly including 2.02 intake 1.60 exaust valves, big block Chevy valve springs.adjustable push rod guide plates {the 4L has a wider valve spacing than chevy} seven sixteenths rocker arm studs and 1.6 roller rocker arms. AC is also going to match port the exaust side and polish the combustion chamber. I decided to leave the intake side alone, I have found out in the past that it`s better to leave the intake stock for good street characteristics.

The rest of the engine parts are going to include a Clifford performance blue printed oil pump. It`s basically a stock size pump that is cast iron {instead of the factory aluminum} that has been completely blue printed. I have one in my current 4.0L and it consistantly maintains 60psi hot or cold. The timing chain is a true roller high speed Cloyes, that is going to have some help with a chain buffer and tensioner from a 2.5L Jeep engine. There are timing gears available but they are designed for racing only and do not have the high mileage ability built into them. The block is going to need a .060" over bore to reach the 4.7L size, it will also be line honed and decked so to make sure everything will be nice and true. All of the reciprocating parts will be balanced, the pistons and rods were allready balanced by Hesco so only the crank,harmonic balancer and flywheel will need to be spin balanced. The gasket I will be using are from Mopar Performance, the complete set comes with everything you need including a high performance head gasket that can handle up to a 12 to 1 compression ratio.

I have not decided on the camshaft that I will be using but it will probably be a solid lifter or a solid roller made especially for this combination. The reason for these choices are because they offer the most horsepower potential and I don`t mind doing a valve adjust once in a while.

The rest of the engine will have an overbored throtlebody, for Just a little more air flow, a modified air box {I will probabaly do a write up on this later} and a Borla header modified to fit a 3" exaust system. I`m still looking for larger fuel injectors at this time, I`ll let you know what I find in upcoming issues.