ive got a 1999 7.4 mpi - so I think that means its a gen vi, with ‘peanut port’ heads. but not sure on the heads, some say they are ‘peanut port‘ in this motor, others say they are vortecs.
I’ve given up on the MPI, can’t get a steady idle, or above 3,800 rpms with a load. Plugs, wires, cap, rotors, iac, map sensor, tps and all filters have all been replaced. Have had it at a shop. They got nowhere either. Ran with brand new gas from an aux tank, no diffference. Fuel pressure is steady 40+ psi.
My thinking is that I’ll pull the motor out of the boat , and if the compression is good, over the off-season replace the intake manifold, throw on a carb, a new fuel pump, and a delco ignition. I know I’ll burn more gas, and won’t get better performance than a properly running mpi motor. But I don’t have a properly running mpi, so this may be my best option.
what I’m having trouble figuring out - does anyone make a cast iron marine intake manifold ( for carbs) that is compatible with the peanut port ( or vortec) heads? Or do I need to replace my heads too? If replace, which heads are compatible with the gen vi block? Small blocks are so much simpler, with more information out there. Not finding much on the big blocks.
I’ve given up on the MPI, can’t get a steady idle, or above 3,800 rpms with a load. Plugs, wires, cap, rotors, iac, map sensor, tps and all filters have all been replaced. Have had it at a shop. They got nowhere either. Ran with brand new gas from an aux tank, no diffference. Fuel pressure is steady 40+ psi.
My thinking is that I’ll pull the motor out of the boat , and if the compression is good, over the off-season replace the intake manifold, throw on a carb, a new fuel pump, and a delco ignition. I know I’ll burn more gas, and won’t get better performance than a properly running mpi motor. But I don’t have a properly running mpi, so this may be my best option.
what I’m having trouble figuring out - does anyone make a cast iron marine intake manifold ( for carbs) that is compatible with the peanut port ( or vortec) heads? Or do I need to replace my heads too? If replace, which heads are compatible with the gen vi block? Small blocks are so much simpler, with more information out there. Not finding much on the big blocks.
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