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Discussion Starter #1
there is a gasket right behind the throttle body that blocks about 10% of the opening has anyone trimmed this gasket? Im going to trim mine and wanted some input
 

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I was looking at that and was thinking about the same thing, I dont know if it helps control the fuel air mix or not. If you try it, please post the results.
 

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Discussion Starter #3
gas is mixed with air further in the plenum, the only thing that is may due is make it leaner at wot which may be good because they are on the rich side to start with (more air and closer to the perfect mix = HP)
 

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If it cleans up your transom,,, pull a spark plug to make sure it didnt lean you out to bad..... which flame arrestor are you running,,, I have the K and N.
 

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Discussion Starter #6
I still have the stock on, I have heard that on the 310 engine there isnt much gain, Ill switch it at some point, which 7.4 do you have and did you see any gain?
 

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I had the 7.4 LX MPI 350 crank,,,330 prop hp,,,, yanked it,, just droped in a 502 MPI last week !!!
 

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Discussion Starter #8
lucky you, Id have to move up to a bigger boat before Id pull my engine, at least thats what I tell the wife
 

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I actually had plans to rebuild the 454 at the end of the season, new heads cam etc., but I came across a GREAT deal on a complete 502 MPI I could not pass it up,,, it needs refrshed (450 hours ) but it runs so I through it in for this season,, I will keep the 454 on a stand just in case this lets loose during the summer as a backup.
 

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Yes, let me know how things worked out. I have a 7.4l (1999). I put a K&N on it. Cleaned up the transom alot and you get a little more mid range "umpf". I have a small boat 99 Hammer so maybee that is why.
 

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jimgoog,,, what plugs are you running,,, I switched to Rapid fire #1,,, between that and the K and N, my transom was pretty clean,,,,, now that 502 is still terrible with both installed so I get to try again !!!
 

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Discussion Starter #13
jimgoog, mine is a 99 20' wellcraft excalibur so we should be pretty close. what prop and mph (gps or speedo?) are you running, also where and how much was your k&n filter
 

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CR, mine is a 99 Hammer, 23 pitch mirage plus. I run full tank of fuel and 4 people loaded with gear 66 on my gps and more around 74 on the speedo. I got my filter from Rex Marine, www.rexmar.com(Great service dept, tech was really helpfull) . I don't remeber the exact price, but it was cheaper than buying it straight from [email protected] It goes on in about 5 min. Well worth it from a looks stand point. It got about 200 more rpm out of it. For me lab finishing will be next.
 

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Discussion Starter #17
well I trimmed the gasket and ran it in the driveway with no problems, so the only thing it should do is lean it out. Im hoping to do a test run this weekend to read the plugs if anyone want to go for a ride let me know the wife says its still to cold
 

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Discussion Starter #18
well I took the boat out on sunday for the first time this year and after trimming the gasket, I had the wife and kids with me so I couldnt take her over 3000 rpms but with a day of running the gasket trimming doesnt seem to hurt, the transom does not show any signs of running rich. I still have to go out and run WOT and check the plugs and my MPH
 

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Discussion Starter #20
I hope to get it out this weekend to see if I gained any topend, Iit did feel alot differnt at 3000 rpms but I changed the prop and went to a thru hull exhaust since a year ago
 
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