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71javelin 09-09-2007 01:56 PM

update gen VI not gen v 454 marine roller motor
i came across a gen v 454 4 bolt main marine motor today. the guys wants 300 bucks for the short block with oval port heads. he said it was a 450hp motor. it's been sitting for 3 years. the boat had dual 454's but caught fire while in dry dock. it will need a rebuild since there is a little rust on the cylinder walls.

is there a difference between the marine motor and car motor?

it that a fair price?

sorry for the newbie question but i don't know chevy at all. i was thinking of using it in my 67 firebird.

update it's a gen VI -- 10237297...454.......96-up...4-bolt, Vortec 7400", "L-29" Gen.VI

Notorious 09-09-2007 02:36 PM

Generally marine applications are adaptable and vice-versa. I'm thinking it might have a reverse rotation cam in it though. If so that'd have to be changed of course. I'm sure someone here will have the full story on what's needed. Marine engines are usually built with good stuff from a durability standpoint.

Dugg 09-09-2007 05:40 PM

I'm not so sure a 454 with oval port heads is likely to make 450HP. But I've been fooling around with aircraft for the last (undisclosed, I'm old) years.

Further, I don't believe most marinas sell high octane gas and therefore, the 450HP isn't coming from high compression.

Marine applications are designed to run at RPM all day and to do so, they're sometimes detuned for service life and fuel burn.

Yup, just opinions.

71javelin 09-09-2007 05:51 PM

i forgot all about having one motor with reverse rotation.

i looked up the newer 454 marine motors and around 400hp and up had rectangle port heads. but that doesn't really make much difference to me since i wouldn't be using the heads any ways.

i called him and asked for the #'s off the block.

any guess if it will have forged rods and crank? it looked like all the new 454 marine motors have forged crank, rods and pistons.

Chevrolet4x4s 09-09-2007 06:54 PM

some of the marine engines (at least sbc's) had inconel exhaust valves also :D :thumbup:

Notorious 09-09-2007 07:06 PM


Originally Posted by Dugg
Further, I don't believe most marinas sell high octane gas

Au contraire, at least the ones around here do.


Originally Posted by 71javelin
any guess if it will have forged rods and crank?

I'm guessing yes.....

302 Z28 09-09-2007 07:17 PM

The marinas around here also sell high octane gas.$$. With all the Chevy powered air boats down here they have to.

Depending on which of the two engines you are getting it may or may not be reverse rotation.


71javelin 09-09-2007 10:05 PM

if it is a reverse rotation. can it be setup to run the right way?

71javelin 09-10-2007 05:35 PM

ok casting #"s say it's 10237297...454.......96-up...4-bolt, Vortec 7400", "L-29" Gen.VI

anyone know about the vortec motors?

will gen IV heads fit on a gen VI block?

Notorious 09-10-2007 05:42 PM


Originally Posted by 71javelin
if it is a reverse rotation. can it be setup to run the right way?

Sure, just takes a cam swap.

DeathRattle 09-10-2007 05:48 PM

Wikipedia's info on the vortec 7400 only claims 290 horsepower @ 4000 and 410 ft/lbs torque @ 3200

71javelin 09-10-2007 08:44 PM

thanks, i've been searching for info on it. i'm guessing it's a mercruiser Bravo, it had fuel injection, roller cam, and large oval port heads.

if i get the block i'll be putting the merlin rectangle port heads i have on it with a nice big cam.

curtis73 09-11-2007 07:53 PM

If its a sterndrive, chances are its not reverse rotation, especially since you said its a bravo. Bravos can turn either direction, so the reverse rotation is simply a shift cable direction change. There are several reputable sources on the topic (none of which I have bookmarked on this computer) but I did have this one:

Its HIGHLY unlikely for that engine to be reverse rotation. The whole point of the later generation outdrives was so they didn't have to make reverse engines, but like was said, change the cam and the distributor gear and you're moving the in the right way.

PS... I forgot to mention... if it was ever a saltwater block (meaning that salt water was used to circulate in the jackets) you cannot use antifreeze in it. Ethylene glycol and salt don't mix, and no matter how much you flush it the pores will always retain some salt.

55BigBlock 09-12-2007 01:52 PM

I bought a 427 marine engine that was in a house boat along with another 427 and twin stern drives. It was reverse rotation. I changed the cam and timing gear setup and it ran great. It had all the best stuff from Mercruiser. Remember engines used in this application are bullet proof, because they are under a constant load. There is no coasting down hill on the water. :)

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