baronbob

I may have soft rings and therefore be headed for a re-build this winter. I would like to stay with my MPI set-up, which probably means heads stay. The obvious is a crank which one? & forged pistons which ones are best suited for a 5# boost? Rod bolts? or rods too? Head work? cam/springs (I plan to stay below 4800RPM). Does anyone sell an up-grade kit for the 7.4MPI?

baronbob

M-1 Procharger-5PSI. I don't think I have blown the pistons. I put a used Procharger on a used 7.4 MPI and I did have had trouble with my intake gasket leaking water into the oil. I replaced the gasket and no oil problems since. The engine has never been completely happy since the install. It does run well @ 4000 RPM. Above 4000RPM the engine varies RPM by +/- 100. The variance was grater however I re-built the ATI fuel regulator and performance got better. I believe the lower end was worn prior to the procharger application. I am seeing oil back up and out the oil dip stick (500 total time prior to the procharger 600hrs now). Compression checks are now in 120#s in the center 4 cylinders (3, 4, 5, 6, 7,) and 150#s in the corners (1, 2, 7, 8,). I have thought that the head gasket might have developed a leak, as the stock gasket is a weak point however various responders to my threads have said I have piston blow-by. My leak-downs were 80#s/50#s in the corners and 80#s/20#s in the center. The guy I bought the Procharger from had no reported trouble. Same engines. His rig was newer however. I plan to run the rest of this season @ reduced power and then totally re build this winter. At that time I will build with forged steel crank, forged rods, and a d forged pistons. If you have a relatively new engine I would try the stock set up with the gaskets replaced if that is convenient. I highly recommend the procharger set up, even with theses problems. If you stay below 5#s and have cold plugs the MPI will retard the spark before a big problem with detonation can do too much damage. If you want to talk 530 587 4700. Bob