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Old 06-07-2009, 08:29 PM
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502 MPI Mag/GIL Exhaust

Has anyone added Gill to a 502 MPI MAG?

Would this make the motor run to lean?
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Old 06-08-2009, 01:36 AM
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I've got 502mpi's with CMI headers and as far as I know, the ecm's are stock. I bought the boat used and never asked. The engines were bought brand new in 2000 with factory warranty, so I doubt they changed anything. No issues with running lean and they have about 350hrs on them.
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Old 06-08-2009, 03:55 PM
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Thanks Griff

anymore help??
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Old 06-25-2009, 02:51 PM
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I have had GILs on my 502 MPI for 8 years. No problem.
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Old 06-25-2009, 08:23 PM
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Don't know if this helps, as not running Gils. But,I've got Stainless Marine on my '96 502 EFI's, with stock ECM's. Runs fine, no issues.
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Old 06-25-2009, 08:29 PM
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I have Gils on my 502, no issues, are you buying new or used?
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Old 06-26-2009, 06:42 PM
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Originally Posted by Griff
I've got 502mpi's with CMI headers and as far as I know, the ecm's are stock. I bought the boat used and never asked. The engines were bought brand new in 2000 with factory warranty, so I doubt they changed anything. No issues with running lean and they have about 350hrs on them.
I also have stock 2001 502 mpi's with CMI's and have had ZERO problems. In fact, cleaned up the black soot on the back after a hard run, picked up about 2 mph, and improved midrange torque. No ECM modifications. They also sound better as well!:-)
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Old 06-26-2009, 07:39 PM
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I do not have personal experience with this setup. But I know 502 mags run rich from the factory and leaning them out with better exhaust would probably be a good thing. If Griff say it works I would trust his judgement. He gives good advice. If in doubt install a wideband O2 gage. I have wideband O2 and it works perfect even a WOT.
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Old 07-02-2009, 01:45 AM
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My 2000 502mpi's have over 350hrs on them with this set up. I ran the MWBP ppoker run this weekend with the sticks on the dash for 90% of the time for the first 31 mile leg of the run. Mine are also dry to outside the transom.
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Old 07-02-2009, 07:51 PM
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We tried to mount some Gils on a pair of 502 MPI's for test runs and there were clearance issues between the port side and the oil filter mount ....The Manifolds were made for Gen IV blocks so I not sure if there is a difference. The Gils are an industry standard but tend to be old school now .... CMI would be nice but consideral more $$$$ .....m
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