need help with 7.4. I.D.
 

very new to boating just got my 1st boat this summer (90 baja 226 es 7.4 454) i bought it with a very fresh reman merc 454 in it. the person i bought the boat from said the origanal motor was a 330hp 454 and he replaced it with a reman merc 454 mag 365. i have no idea what engine is in this boat is there any way i can tell. also, i keep reading on here that there many diff. generation motors how can i tell what mine is. the whole reason i ask is i would like to to do some mods. over the winter and i would like to know what i have. thanks-

Re: need help with 7.4. I.D.
 

As we can all tell you from past experience, you cannot go by what the previous owner told you about the engine. They usually lie about it or are simply mis-informed. You could pull the valve covers and get the head casting numbers to determine which heads you have. I recommend pulling BOTH valve covers. Some people mis-match heads, if you can believe that.... :rolleyes:
You could also get the block casting number off the rear, port side of engine. You will only be able to tell what year and "Generation" the engine is from this.
You`ll never know what cam, pistons or crankshaft you have unless you disassemble engine.
Look at your carb and intake. Determine what you have there, this could help a little.
Good Luck!

Re: need help with 7.4. I.D.
 

well i know the motor is a new reman b/c i had to pay the balence at the local dealer to get the boat. everything should match. what should i look for on the intake and casting # on the block?

Re: need help with 7.4. I.D.
 

See if this helps with serial numbers

http://mercruiserparts.stemtostern.c...er_engines.asp

Re: need help with 7.4. I.D.
 

thanks, i will have to go home and dig up some #'s and see what i got.

Re: need help with 7.4. I.D.
 

I've got the same boat. Let me know what you're getting for speed. BTW, where are you from?

Re: need help with 7.4. I.D.
 

it is really easy to tell the difference between a 330 hp and a 365 hp, one has oval port heads and the 365 has rectangle port heads. that is the external stuff. also internally different. Ed

Re: need help with 7.4. I.D.
 

right now with a borrowed prop which is totaly wrong for my boat (23 pitch cleaver) i am getin 61mph on gps at 4500 rpms trimmed up alot. i am useing my friends cleaver right now while my good prop is a houston prop. works geting labbed. i am from upstate n.y. (hudson river).

Re: need help with 7.4. I.D.
 

Hey 98 welcome to OSO, and the wonderful world of go fast boats :D

Got mine about 3 years ago and was {often still am} totally lost. What I did to learn, and still do, was/is visit here and other boat sites frequently and read as much on the tech threads as possible. And I asked a chitt load of questions....and still do LOL.

You'll find allot of these guys are very knowledgeable and will be generous with helpful info.

Suggestion if I may.....There's a book called Big Block Chevy Marine Performance, written by Dennis Moore. Lots of info and explanations about the different BB engines. Also includes some build info. There was a thread going on here that mentioned the book was difficult to find. But there is probably some around if you look.

I'm in central NY...Syracuse/Oneida Lake area. Hope to see ya out on the water some time :drink

Re: need help with 7.4. I.D.
 

thanks for the welcome, and this site is very helpfull who knows what i would have messed up if i didnt ask or read qeustions on here. :D

Re: need help with 7.4. I.D.
 

where on the enigine block is the serial number? :cool:

Re: need help with 7.4. I.D.
 

If it is a Merc rebuilt there will be a small plate riveted on to the block on the starboard side just above the starter.