s022mag

Has anyone every swapped just one motor vs both or rebuilding the one? And if I were to replace my 454/425 out of my 88 311 formula what would be a good match and what would I exactly be looking for?

f_inscreenname

If they are not exact or at least close your throttles will always be in different positions and you will be chasing rpm's all the time. Also if one motor is out it makes it a lot easier to get the second one out.

dereknkathy

so, you have 1 good and 1 bad motor? i would be looking for a 425 hp 454. you are obviously happy with boat as it is. if you upgun 1 side, you could do same top end on other motor, knowing you are gonna kill the already getting tired bottom end by running it harder than ever...

endeavour32

iTrader: (4)

022-
First we need some details on your engines. How many hours are on them? If you have less than 300 hours on them, most likely get away with rebuilding the one bad engine. However, I'm currently rebuliding a pair of 454 mag engines with 230 hours on them and I'll tell you I'm shocked at how bad the heads were. All the exhaust seats were sunken and needed to be replaced. What I would do if it were me is pull both engines. Rebuild the bad one and have at least a vavle job done on engine number 2. Otherwise you'll have one strong engine and one weak one.

s022mag

The motors have 650 hrs on them. The port motor has always given me issues. Leaky tranny that burnt up, busted spark plug that needed drilled out, now low oil pressure at idle and it even lags behind the starboard motor when running. I fired them both up last night and the starboard just sounds so much better. I'm really getting flustered with it.

fireboatpilot

650hrs? Pull them both and freshen them both up, IT'S TIME! Besides you know as soon as you get the one rebuilt and drop it in the one you thought soulded good next to the crappy one is now going to be the crappy one so while it's down and apart do them both, or, do it twice. My 2 cts, and believe me I've chased the one bad motor around for several seasons, back and forth.

s022mag

When u say freshen u mean top end or bottom end too. And should it be done now or can I stretch it to winter time?

dereknkathy

is the one gonna make it to winter? i thought not. another possibility. i like having spares. buy a truck take-out. put rod bearings in it. put your cam, heads, pan and a new oil pump on it and run it. now get your bad one redone. next swap it with other and get it redone. now you have a runnable short block as a back up. things seem to break less when they know you have a replacement for them...

endeavour32

iTrader: (4)

Listen to Fireboat and I, and at least inspect the bearing and replace the rings. Then have your heads rebuilt (valve job, new springs and most likely guides.) What darelnkathy is saying is stupid. You're heads are most likely part of the issue and buying a "truck" take out is going to do you no good as your not going to find a new 454 take out let alone one that even resembles a 425. GM hasn't put a 454 in a truck in decades and never put one in with domed pistons and forged crank, ect! Truck engines are basically 330's.

fireboatpilot

What I meant was time to rebuild them both. Rings, bearings, valvejobs the works. If my boat is down for one engine out then I might as well pull the other and take a look see at whats going on in the other one. Of course you can have premature failures of componants but at 650 hrs IMO their running on their last leg anyway. Besides didn't the one fail anyway? So whats making it thru this winter? Its one thing to go out boating thinking everything is fine and having something fail on you but to go out knowing something will probly fail or at least give you headaches, whats the fun in that?