Mopar MPI success story
OK, RSD-
Now for the serious reply...
I can tell you what most people problably did wrong installing an MPI and I can tell you what I did right.
In most cases many did not do their homework and set themselves up for failure...
Most ignored the stated warning to not install and MPI on a worn engine.
The presence of carbon build-up in their old, oil blowing mills is a sure fire way to ensure ping (pre-detonation). Plus, the old fashined style combustion chambers were not designed for FI. Add to this the percentage of engines that have an after market or performance cam. Three strikes, then you are out (of luck).
I have NEVER heard a report of pinging if a 4.0 head is installed on a 258 with the MPI. And most have heard that there is a water jacket issue to deal with installing the 4.0 head.
Hesco co-developed and sell the MPI kit but most bought theirs from a discounter like Pro-Tech in Denver (still in business??) and most do a 'by guess and by golly' cam choice, again ignoring the stated warning about using a hot cam with the MPI.
I learned a long time ago that I always loose when I gamble.
I wanted to try re-building an I-6 though I struggled with the knowledge that tossing in a GM 350 had a LOT of advantages. And after doing MY homework, I realized that a performance I-6 build-up would be every bit as or even more expensive (not even counting what a set of roller rockers would cost) than using a new crate V-8.
One thing that influenced my choice was what a long time local Jeep guru said ..
"Installing a V-8 is one way of ruining a good Jeep!"
Many can, should, and will disagree with that statement.
Having made my choice and prefering not to gamble, I called Bennie at Hesco to get advice before I stared, knowing (because I'd done my homework) that sucess hinged on compatability of the MPI with all components.
After a thourogh consultation on the phone, Bennie shipped the MPI, a ported new 4.0 head w/welded jackets, a set of matched factory style rockers, a Cyotes double roller timing chain (4* advance), a Melling heavy duty (not hi-volume) oil pump PLUS their MPI/DYNO PROVEN 214-R cam.
The result (still only couple hundred miles on it) was WAY beyond my highest expectations. It runs like a scalded dog, has torque up the kazoo, and top end going in to 5000 RPM (a new set of ARP rod bolts and a good, full balance job help here). After it's warmed up and I punch it in first or second with 35's and 3.37 gears the front end raises up, I'm pushed to into the back of my seat, and the hair stands up on the back of my neck! It has twice the power of my kid's new 4.0 Sahara and even he said the new build had "balls". And that is something coming from a 19 year old.
Soo... pay your $ and take your choices ... just do your homework first ...
I'd never gamble with an MPI on a 4.2 head. Your odds then are 50/50 at best.
JAF
http://www.monsterslayer.com/jeep