K&N Flame Arrestor for 7.4MPI
 

OK, for the non-mechanically inclined (myself), can anybody tell me the basics of how to install this sucker?

I'm not a total idiot, I just don't know where to start.

Thanks!

there is a big clamp on the plastic flame arrestor loosen it and wiggle the old one off and slide the new one on and tighten the clamp thats it about 3 mins worth of work

If yours is like mine then you have to remove the old studs with double nuts or vise grips and install the new adapter with the supplied allen bolts and then clamp down the filter clamp,btw mine is a 502 mag mpi

Where are you getting the filters? MerCruiser or Auto parts stores?

Rick,

I got the flame arrestor from Martel Brothers... it's a performance shop in Katy, TX (close to where I work.) They also are one of K&N's bigger on-line sales sites... www.martelbros.com. It is the marine certified, race/off-road use only, flame arrestor. (Part 59-5004)

crmax,

Do I have to pull the plastic engine cover off to get to it? Do I have to leave it off to make the K&N fit?

Thanks!

I got mine for my 500 at Martel bros too. Good prices. I now need to get them for the new ride. 7.4mpis like yours.


Tim

29 Fever,

Just under $50 for the K&N for the 7.4MPI.

Yea remove cover (torx head)...then one hose clamp

Any idea what size Torx bit that is?

mine didnt come with the cover the forgot at the factory to put it on, I like it off anyhow. I got mine from rexmarine

and Ive seen the k&n on with the cover so yes it should fit back on

Well, including uncoverring the boat, opening the hatch, pulling the over off, swapping the flame arrestor, reinstalling the cover, closing the hatch, and covering the boat... it took about 10 minutes.

Much easier than I anticipated.

Thanks for the input.

I also have a 7.4 MPI in my boat did any of you guys notice or see (on gps) any performance increase???

pstorti,

I haven't tried yet... although I'm at the limiter with the stock filter. I'm changing to a 24p Bravo I from a 23p Mirage Plus this weekend... So I won't REALLY know. But just by looking at the thing, the engine is going to breath easier.

Oh yea the gasket behind the throttle body protrudes into the port I trimmed that out to. Performance gains unknown at this time because I havent gotten a prop on it yet that dosent smack the rpm limiter but midrange cruse seems better

I put the k&n on at the same time I put the thru hull exhaust on my mph went from 58 to 61.5 both were gps readings

dloftis
 

Which engine do you have. They gave me a different P/N

Rick,

I've got a Mercruiser 7.4MPI 2001 (same as 2000)

Check this web site out:
http://www.knfilters.com/marine/boats.htm
It lists most Mercruiser motors and the appropriate part number.

(BTW: The 59-5004 is correct for my engine... it fit perfectly.)

dloftis,

The 59-5004 looks by numbers like it's higher (taller) than the stock arrestor. It shows 6" and although mine's down at Travis from memory that's taller than stock. Did you find that to be the case or is 6" about right?

I bought my set up from trenton marine 502 mag/mpi had to dril n tap a fitting for the breather line what a pain.
0% performance difference. just looks better