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-   -   454 Mag MPI gen v rebuild help (https://www.offshoreonly.com/forums/general-q/363087-454-mag-mpi-gen-v-rebuild-help.html)

BillK 09-26-2019 05:49 AM


Originally Posted by cableguy1979 (Post 4707976)
but I have to ask why do people keep thinking I need new rods?

Probably because it is pretty rare for main bearings to fail before rod bearings so when you said the crank would need turning we probably all took it to mean that you had messed up a rod bearing. If you did indeed "spin" a main bearing then you might as well include a block in your estimate.

As far as your machinist turning a crank and supplying bearings for $150 . . . . unless he is a friend and doing it for you for no profit tell him he is not doing our industry a single bit of good by being that cheap. Those are 1960's prices. Is he going to magnaflux the crankshaft for that price too ?

SecondWind 09-26-2019 11:45 AM

https://cimg0.ibsrv.net/gimg/www.off...5ca6ecd7ad.png
Here’s a pic of the Tyler Crockett 454 Mag EFI upgrade. Upped the HP to 461, the sound upgrade was worth every penny.

cableguy1979 09-27-2019 10:46 AM


Originally Posted by BillK (Post 4707997)
Probably because it is pretty rare for main bearings to fail before rod bearings so when you said the crank would need turning we probably all took it to mean that you had messed up a rod bearing. If you did indeed "spin" a main bearing then you might as well include a block in your estimate.

As far as your machinist turning a crank and supplying bearings for $150 . . . . unless he is a friend and doing it for you for no profit tell him he is not doing our industry a single bit of good by being that cheap. Those are 1960's prices. Is he going to magnaflux the crankshaft for that price too ?


Why would i have to include a block for a spun main bearing? I assume its a main bearing because the knock I hear only happens once coming of a hard rev. A rod bearing usually knocks every rotation. I havent broke into the engine yet and Im think of taking it to the lake again to see if it might be something else.
He is semi retired and does it for fun. Yes his prices are 1960's and he is a honest man. Hes not trying to rape people but simply keep the doors open when he feels like working.

cableguy1979 09-27-2019 10:48 AM


Originally Posted by SecondWind (Post 4708030)
https://cimg0.ibsrv.net/gimg/www.off...5ca6ecd7ad.png
Here’s a pic of the Tyler Crockett 454 Mag EFI upgrade. Upped the HP to 461, the sound upgrade was worth every penny.


Looks like a expensive upgrade. My boat isnt worth what you have in this motor. Guess I stick with stock. Man if it sounds as good as it looks im jealous.

cableguy1979 09-30-2019 08:56 PM

What are some of the must do's while im in this engine? Im not trying to build a very expensive engine. It's going to be a budget build and other than machine work im doing it myself. If the rods are weak I'll replace them.

cableguy1979 10-01-2019 08:51 PM

Called Tyler Crockett today and they have a special ground cam and ecm chang that should yield a easy 50hp. I assume no other change was necessary.

Called comp cam and they have a cam but man did they not seem to know anything about mpi engines. Stated they have a cam but couldn't tell you how aggressive it was and they don't give out hp numbers. Also stated no computer change was necessary. Stated it would increase hp but couldn't tell you much about it.

Blueabyss 10-02-2019 04:16 AM

What Boat?

SB 10-02-2019 10:01 AM


Originally Posted by cableguy1979 (Post 4708892)
Called comp cam and they have a cam but man did they not seem to know anything about mpi engines. Stated they have a cam but couldn't tell you how aggressive it was and they don't give out hp numbers. Also stated no computer change was necessary. Stated it would increase hp but couldn't tell you much about it.

They know nothing but the computer does not need reprogramming ? WTF ? I can't believe this would be an answer today in 2019 and it wasn't an acceptable answer back in 1989 !

Always talk to a computer programmer, like you have, that has experience with the engine and computer in question, + can tell you what cam(s) they have programmed for successfully.

Mr Maine 10-02-2019 10:16 AM

If you are using stock cast iron exaust i would build it as a stock rebuild. Most larger cams are gonna require better exhaust to avoid reversion issues.

BillK 10-02-2019 10:47 AM


Originally Posted by cableguy1979 (Post 4708892)
.......and they don't give out hp numbers.............. Stated it would increase hp but couldn't tell you much about it.

You seem to be stating that in a pretty negative manner.

My opinion is that if a camshaft company is telling you that their cam will add #### horsepower to your engine I say they are full of it. Unless they have built your exact engine with that camshaft and have put it on a dyno before and after there is no way they can tell you a horsepower figure. They might be able to take an educated guess but that's it.


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