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pslonaker 06-28-2010 09:04 AM


Originally Posted by ridefast77 (Post 3144189)
not sure if any thing is rong but i cant get my rpms over 4200 wide open and trimed out i was told it should turn more like somewere in the 4800-5200 its a stock 7.4 (454) mpi with stanless marine exhaust is that true

NO...it is not true. If you are running a 7.4 (non mag motor), then your rpm range should be around 4200 to 4600 and no more. Turning a 7.4 up to 5000 and more is not pushing the limits...it is shoving the limits. More than likely, you will have a rod hanging out the side of it.

XT-Innovator 06-28-2010 11:07 AM


Originally Posted by PSlonaker (Post 3146251)
NO...it is not true. If you are running a 7.4 (non mag motor), then your rpm range should be around 4200 to 4600 and no more. Turning a 7.4 up to 5000 and more is not pushing the limits...it is shoving the limits. More than likely, you will have a rod hanging out the side of it.

Agree...

My 29ol with 7.4 MPI's rev limiters kicked-in about 4650, but the older 7.4 carbed motors like my 92' 240 would run almost 5000 if overtrimmed with a 23p Mirage. Rev limiters were the best thing invented for marine engines...

XT

dogghouse 06-28-2010 11:42 AM


Originally Posted by PSlonaker (Post 3146251)
NO...it is not true. If you are running a 7.4 (non mag motor), then your rpm range should be around 4200 to 4600 and no more. Turning a 7.4 up to 5000 and more is not pushing the limits...it is shoving the limits. More than likely, you will have a rod hanging out the side of it.



100% right!! if you had MAGs (385hp) not MPIs (310hp) you would be able to push them a little more. Not the MPIs ive been thought this already.

good luck.

AIR TIME 06-28-2010 08:34 PM


Originally Posted by ridefast77 (Post 3146236)
ill have to fine one

did you change your fuel/water filter that can cause a loss of 200 rpm. give brett at bblades a call he has a prop exchange program, but if you didn't change the f/w sep do that 1st.your hull is different from the ol hull your is a 21 degree if I remember 240 sport /ol was 24 degree.

ridefast77 06-29-2010 08:53 AM

thanks guys, i looked on my motor covers and it dose say rpm 4200-4600 so i should be able to pull 4600 right, but im not so i guess ill try a smaller pich prop

AIR TIME 06-29-2010 11:39 AM


Originally Posted by ridefast77 (Post 3147225)
thanks guys, i looked on my motor covers and it dose say rpm 4200-4600 so i should be able to pull 4600 right, but im not so i guess ill try a smaller pich prop

Call brett he has a prop exchange he may let you try a small prop but it might be higher rpms but slower speed. you will pick up speed with a labbing a prop and rpms. also check the fliter I told you if you did not put a new one in. a labbing can get you up to 300 rpm. but brett may want you to try a rev 4 prop 25p they have worked good in bajas cause of the deep X= deep prop shaft. I will ask him to look over here if he has a chance he could explain better than me. your boat should be faster than a ol 24 cause its lighter/smaller deadrise 21 degree not a 24 just don't go buying props from Co's that once you buy it your stuck with it.:coolcowboy: call me if you want 617 833 3327, just hanging around two day waiting for flywheel and driveplates so we can put the 1100sc in the boat.

ridefast77 07-01-2010 07:54 AM

thats cool ill try to call you later thanks


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