Help identifying which 454/ 7.4L engine this is?

[mattyd272]

Anyone able to help identify which 454/ 7.4L engine this is? The boat is in another state so I cannot go look at it myself. It's in a 1996 model boat, and it is assumed to be the original motor with about 500 hours. Hoping there are some visual separators that you experts might be able to pinpoint.

 

[tpenfield]

Based on the valve covers it is either the Gen 5 or the Gen 6. It would be better if it was the Gen 6. The engine serial number will be important to further ID the engine.

Obviously a carbureted version & raw water cooled.

 

[dubs283]

Agree w/t. Gen 5-6. I'd be more inclined to gen 5 given carbureted. Mercs mpi 7.4/454 engines used the final designed gen 6 for most if not all of the production run.

I've asked here about the history of the 454 due to its outstanding design and performance in a marine engine application but haven't gotten much response. It's a shame GM discontinued production, I've heard mercury owns the rights to it among other GM long blocks along with the foundry in Mexico. Have not confirmed as of yet due to other interests occupying my mind at times

 

[Fun Times]

This one just has more of the 454 Magnum appearance to me vs being the 7.4 Bravo design found in and around 1996... plus searching the number seen on the oil filter adaptor sort of helps support that visual by riser design.

As mentioned, try to get the engine serial number as it should help too.

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[mattyd272]

Thanks for the help. The seller is going to try to get me engine serial today or tomorrow so I can confirm.

Im a bit new to these type of motors. It looks really clean. Any concerns about the little sign of rust where exhaust manifolds meet risers?
Isn't there normally a water hose connected to the riser, where instead it's just capped off on this motor?
Sounds like they're pretty reliable. 500 hours not too big of a deal?

 

[04fxdwgi25]

That engine is crazy clean. Rust at the manifold / elbow joint can be cleaned up. On next maintenance cycle, you can split them, clean up, prime and paint, then install new "GOOD" OEM graphite gaskets (not the green paper ones) and reassemble.

Those capped off fittings are normal for a raw water cooled manifold with OEM elbows. Those fittings are used on a closed cooling system where the manifolds are cooled by engine coolant and the raw water discharge from the heat exchanger is plumbed to those fittings to cool the elbows and be discharger out through exhaust (there is also going to be a block off plate installed between the manifold and the elbow in that set up, isolating raw water from engine coolant)

 

[mattyd272]

Thank you so much for the info!

 

[QBhoy]

Hi. It’s either a replacement re power unit or it’s had a few diy bits added to her from the norm. The rocker covers and distributor don’t look standard to me. I also think it would be a rare thing to have a 1996 carb 7.4l engine supplied to a new boat in that year. My guess it’s that it’s been a replacement engine from elsewhere or a road vehicle, or it’s been messed with and added to from what the norm would be. There wouldn’t be many 7.4 put in boats new in 1996, that weren’t an mpi, if at all. I’d think.

 

[mattyd272]

Thanks again. I finally have the serial: 0F603985. Does this help provide more info? If this is indeed a Gen V, anything to be concerned with on this version 454 with about 500 hours?

 

[Fun Times]

0F603985 shows the engine to be a 1996 MERCRUISER TB5, W/PS, TWOPCEX, WORO, GEN-V 7.4L BRAVO Model number 474B110JS.

 

[Scott Danforth]

Casting numbers

 

[04fxdwgi25]

Thanks again. I finally have the serial: 0F603985. Does this help provide more info? If this is indeed a Gen V, anything to be concerned with on this version 454 with about 500 hours?

I have a '95 GenV block 454 Mag, basically what you have, with some special parts. GREAT engine if the maintenance is done religiously. Be religious in changing oil, using premium gaskets where needed, if you have the raw water and mechanical fuel pump drive, change the oil in it every year. Only things that gave me trouble were the fuel pump and carb from time to time. I give the ethanol pump gas I had to use credit for that (In NC, I have access to non-ethanol pump gas and strictly use it).

My last big block was the 7.4 and had 1550 hours on it when I sold it 5 years ago, ran like a top and I speak with the buyer every spring and he says it is is still a power house that sounds like a new engine.