I have a 5.9 Magnum that I am going to swap into my 98 Jeep Grand Cherokee along with a 5 speed transmission. While the 5.9 is out I plan on doing a new water pump and all other cooling system components, intake plenum gaskets along with the Kegger mod, valve cover gaskets, oil pan gasket, rear main seal, and new timing chain and components. For performance I am getting the Harland Sharp 1.7 roller rockers, bigger throttle body, Davis ignition kit from Summit racing with Autolite 3923 plugs, some kind of air intake, shorty center dump headers with a 2.5" true dual exhaust and I am going to have it tuned by Flyin Ryan. Any other maintenance or performance upgrades I should do without being too expensive?

 

Replace all your expansion plugs (freeze plugs) along with a high volume oil pump. This will extend the life of the engine quite a bit and the expansion plugs are real boogers to replace in the car.

 

If it was me, instead of roller rockers, I would put that money towards a different camshaft and springs. Roller rockers will give a little more lift, but no more duration. Also, the factory springs, are weak and close to max lift when new.
.Another thing , if possible I would go with long tube headers.
Talk to your tuner, but I would put those 2 mods ahead of bigger throttle body, ignition kits and shorty headers especially if money is tight.

 

long tubes won't fit in a Grand Cherokee center dump shorty headers are the only way to route the exhaust so it will get past the starter or firewall. A cam and springs is a little more than I want to get into with this engine.

 

Not a lot of price difference between the rockers, and a cam/springs.... You are already going to get a tune, so, that isn't an issue. Likely get a lot more bang for your buck as well.

That said, the 1.7 rockers don't increase advertised duration, but, they DO increase duration at .050 lift...... due to the higher ratio, valves will open sooner, and stay open (at .050 or greater) longer. It's a good upgrade for an otherwise stock motor, good for about 10 hp/tq.

 

Didnt think about the headers not being made for a jeep. FWIW I have the same problem with a 4wd dakota.... Nothing but shortys available.

 

Quote:

Originally Posted by HeyYou

That said, the 1.7 rockers don't increase advertised duration, but, they DO increase duration at .050 lift...... due to the higher ratio, valves will open sooner, and stay open (at .050 or greater) longer. It's a good upgrade for an otherwise stock motor, good for about 10 hp/tq.

Agreed, but it is such a slight amount of duration. 1or maybe 2 degrees?

 

Will a Cam and springs work with the stock rockers, and what cam and spring combo would you recommend?

 

Also what all is involved with installing a cam?

 

You never said what year, If it's ZJ(1993 - 1998) there are headers made but not cheap...
https://www.summitracing.com/parts/d...grand-cherokee
Block huggers are another option but they are not made for the magnum only the LA's. You can mod them to match to a magnum.