4 you motor guys..I have a ?

[Aqua Boogie1]

I just found out that the motor thats in my boat came straight out of a car, 6.6 Firebird...403 block. The mechanic that was working on it told me that the motor didn't have marine applications on it. Now my ? is, what is the difference a auto motor and a marine motor? What changes are to the motor to make it a marine motor?

[Hallett19]

Depending on what you put it in, you need to get rid of and add certain things. There isnt really much of a difference at all. Clearances should be looser for boats considering they spend more time at higher rpm's. But you no longer need a water pump if its on a jet, so that goes, you need water cooled exhaust, so that should be on there. A larger oil pan is a must for boats as well as a rear pickup. Most smog equipment it gone. Marine carb, which is not neccesary, but strongly recomended as well as a marine fuel pump, if its mechanical. Other will chime in on this, but as long as that puppy runs, dont worry too much about it.

[Liberator TJ1984]

If its already in your Boat and was working ?? whats the problem ??? Many a motor has gone straight from the Junkyard into a boat and lived long lives around here...I am just assuming you have all the brackets and mounts..if not then you may have trouble matching things up.???
Gopherrr

[OMEGA_BUBBLE_JET]

the clearances on the bearings and pistons is biggest difference. The cam for a boat is different also. If it is a stock 403 rated at 180 hp I wouldn't think it would make the best boat engine anyhow. I would highly suggest you pull the engine and go through it. there are no emmission standards for boats so you could make that 403 run. IMHO though you would be better to get a BBC and start from there. They are much cheaper to buy parts for and hp is attainable with less money. If the engine is in fact straight out of a car you're asking for trouble and would be lucky to make it through one season without spinning a bearing.......Good luck.
Omega

[skeepwerkzaz]

The 403 is actually an oldsmobile engine, not a pontiac. The late 70's firebirds came with a plethora of different powerplants. Buick v-6's, pontiac 400 v-8, chevy 350's and the olds "small-block" 403. From what I can tell, not a very formidable powerplant, but it runs and you own it so drive it till it stops!!!!
[ June 04, 2003, 12:51 PM: Message edited by: skeepwerkzaz ]

[Blown 472]

403 olds motors came with steel cranks, not a bad little motor really.

[kp216]

Aqua Boogie - My boat also has the Olds 403 in it from the factory, and is rated at only 245hp at 4200 rpm, which as said earlier, is 65hp more than what they were rated in the cars.
They are not a strong motor, as they have windowed main webs, so the bottom end is relatively weak and the heads are pitiful. They can be built to make some pretty decent power but, it requires $$$.
If it's already in there, you might as well run it until you decide to build something else.
Me personally, I'm probably going to run mine until I can build a 460.

[Aqua Boogie1]

Thanks guys.....I didn't think that there was so much of a difference from what I already knew. I just kept hearing "there's a big difference". More than likely I will upgrade to a 454, not trying to break the bank but just have a pretty desent ride. Thanx for the info....