View Full Version : BBC 454 - advice on new valvetrain parts

03-18-2012, 08:34 PM
At least I know for sure what this thing is!

I got this engine in my "as is" Donzi Black Widow 24' purchase a couple weeks ago, and have since taken the heads off to be hot soaked / blasted and have the valves re-seated. One valve was bent, but no obvious damage was done (slight nick on piston head).

I ran the block number as:
10237297...454.......96-up...4-bolt, Vortec 7400", "L-29" Gen.VI

So I'm actually pretty psyched! The Gen 6 Vortech 7400 is a strong engine, with a 4-bolt main and roller cam setup. Plus while the thing "only" made 290hp, it made 440 lb-ft of torque :boggled::eek: (stock) - so obviously this is going to be different in my setup w/ Holley 800, Torker II manifold, and Stainless Marine manifolds. I'm confused about how Donzi listed this boat as 365hp though - I believe the 290 was for a conservatively tuned EFI system on the Dually pickup trucks and tow trucks, from what I can read about that engine block. Wikipedia data would be generic and under a carb marine application it could have been set up very different.

Other history I've discovered on the engine - it's got .020 pistons in it which I assume means it's been bored .020 over stock. Perhaps this was done when they put the engine in the boat as a reman - since the engine has to be pretty recent. I was told that Donzi put 454s in all of the Ford 460 boats in 1993 as a recall, which would mean I'm a little confused as to how a Gen 6 "96+" engine ended up in the boat - unless the stock 93 454 blew and they put a reman Gen 6 in around late 90's or early 2000s.

Anyways, the machine shop is going to want parts for the heads soon. I have no idea what cam is in the boat, so I think I'm going to play it safe and buy HD springs for the valves. Is there any disadvantage to running HD springs if it's actually a stock cam still?

So I'm going to list parts, and would LOVE it if everyone could chime in on the parts they'd use in this situation. I also need a new t-stat. The housing is "bonded" to the gasket and I have no idea what part number the gasket is since details on the engine / year / application are sketchy. I think I can find the other gaskets though. Any preference on temps to run?

-head gasket
-intake manifold gasket (Edelbrock Torker II)
-waterpump gasket
-valve cover gasket (if I order new "bling" valve covers, will they fit?)
-exhaust manifold gaskets (how do I find the part # for these.. ?)
-carb/intake manifold gasket (do I get this from Edelbrock? - running Holley 800 CFM)
-new tstat
-new spark plugs (TONS of conflicting info on these)
-new springs
-new valve (guy at machine shop is going to find this he said) others will be re-seated
-new pushrods (I was going to just run the generic GM Performance set, like $63)
-new lifters (I was thinking it was a flat tappet motor - no marks on cam for cyl. that bent valve - should I reuse since they're roller lifters?)
-alum. roller rockers
-stud adapter set for vortec heads
-probably new belts while I'm here, the serpentine system is totally custom so I'll have to follow the existing #s)

Any other thoughts? And please resist the urge to suggest that I should rip out the motor and replace it with a $15k ZZ502 or full rebuild. Yes, that would be nice - and if the boat wasn't a 22 year old "oddball" I might consider that, but I'll probably keep it for a year and move up to a slightly smaller ZX - for now considering we skipped spring and it's 75 deg out, I'd like to get the thing on the water and enjoy my first Donzi :boat:

Before and after - well, no "after" for the heads yet - but still. Our consensus is that he let the motor sit and rust w/o fogging it, started it up and ran the $hit out of it, valve guide grabbed and valve bent - maybe water got through there somehow or the rest of the water is from condensation (there was visible condensation forming on rockers when I took off the valve covers) I cranked the engine for a long time checking cyl compression and such, so it might have mixed. Oil on dip stick is pristine. Note valve contact in 2nd pic, have been told it's cosmetic and to throw the thing back together. ;)

03-18-2012, 09:34 PM
As far as your engine output figures...each application uses different versions of a similar motor. There isnt an emission system on your boat like there is on a truck. For example...you can't look at a spec sheet for a 5.9 cummins out of a dodge truck and think it is going to apply for a 5.9 cummins that is specified for an irrigation pump or a ford 650...they are all set up differently.

03-18-2012, 09:54 PM
I understand your point of view, and as a mechanic (custom motorcycle builder) I too would simply tell a customer to rip out the engine and throw in a new one or spend the $$$ on a rebuild, but there are times when a motor looks like this and might be totally fine/bulletproof for many seasons to come. IMHO that route needs to at least be explored before I think about removing the engine.

Where I am in Northern Virginia there isn't anyone who can easily remove the engine - and those who can are SOLEY interested in selling me their fresh rebuild 500+hp engines that they've got sitting around for $5500-12000.

I came to this conclusion based on the fact that the bent valve WOULD cause the motor to run like crap and be nearly unusable, but would NOT cause damage to the bottom end of the motor (based on the superficial nick on the piston, and the fact that the cam was clean and intact). The bent valve on the heads when I removed them would seem to signify that it was the "end-all" event of the engine, at which point he sold the boat.

I've wondered about the oil cooler on this thing.. what's the procedure for checking them? If I pull the filter and inspect it for water, that would tell me if water entered the engine when it was actually running (not sitting) right?

edit: and yes, they were rusted. Everything was rusted - again due to the fact that I believe he let this boat just sit and ran out of time, $$, and energy to screw with it - said he took it out one time, wouldn't plane and seemed to have no power. He failed to mention the "boom" moment, but a stuck valve would cause the power issues. This boat also has a seacock water pickup with belt driven waterpump - will these types of pumps allow water to enter the exhaust prior to the engine running?

tnc110 I'm aware of that fact, but I was really asking for what Donzi did to the engines to make them reach their rated output per the Donzi literature - AFAIK the Mercruiser blocks had similar applications to tow vehicles and such, and I believe this block casting # was also used in the 454 MAG engines.

condensation when I popped off the valve cover, and stuck valve:

03-19-2012, 01:29 AM
Fixx speaks the truth....

From those pics, I would hate to try doing just the top-end. You're asking for trouble.

He's also right that it's not that hard to pull the motor. Heck, you've already done most of the work if you've got the heads off! Just a few more bolts and it'll come right out! If you don't have a cherry picker, you can rent one for only a few bucks. You'll only need it for an afternoon. If you're worried about the lift-over, pull the tires off one side of the trailer to get the boat lower. Even sitting on the hubs the trailer will be high enough for the cherry picker to roll under. Worst case, you don't have that much weight there with just a short block. Some creative work with a rafter and come-along and you could pick that sucker right up. Only a few hundred pounds now.

You'll be kicking yourself if you put money into the top end only to find the bottom end has a problem. And looking at your pics, there's a better than even chance there's a problem.

Not trying to be a downer...just trying to save you some headaches down the road.

03-19-2012, 09:34 AM
Thanks for the replies - I'll hit your points in a bit since I'm at work fixx, but I see what you're saying. There's certainly no signs of cracks in the cylinder walls or valley however.

The engine hatch weighs like 45604865409lbs and I'm not sure how to rig it for removal.. or where to put it, since the engine will likely be out for a long time.

And nah I'm not trying to flip it yet - since that's exactly what the guy was trying to do who I bought it from!

Wish I knew what was going on in there.

03-19-2012, 10:11 AM
I forgot you were dealing with a 24; I was thinking of a 22. I pull my hatch solo and just lean it against the garage wall.

Sucks not having friends around to help. I'm in that same boat. My one helpful neighboor moved a few years ago and there's nobody else on the street I'm comfortable with asking to lend a hand. And the girlfriend, though she'll try if I ask nice enough, isn't really much help with lifting big things. :shades:

03-19-2012, 08:47 PM
i use a forklift to remove most of the engines and it having side shift makes it a whole lot easier to remove engines from the side of the boat..

There you go bragging again. No need to rub our noses in it! :wink:

03-20-2012, 10:19 AM
Well, clearly you don't need all that stuff taking up valuable shop space. If you want, I'll help you out by taking that forklift off you hands. I'll even give you $3.50 toward shipping it out here to CA.

I'm just that kind of caring, giving guy! :wink:

03-21-2012, 11:02 AM
Okay everyone, your voices have been heard.

I was looking at nearly $1000 just on the heads, and they'd still be less than ideal anyways. Once I started screwing with the block and getting everything back together, I'd be half way to a new engine anyways. THEN if something did go wrong, I'd be out that much PLUS whatever a new motor would be.

..so yeah, it's painful now considering there's a little troll in the back of my head telling me the damn motor could be fine (if the oil thing was just a cooler issue for example) but it's not worth the risk. I can really enjoy the boat with a new engine and wouldn't hesitate to take it offshore or out into the bay.

So here it is, I'm getting a crazy deal on it - hopefully I can get the thing installed for under $5k if I give him my old stuff as a core - total turn-key setup.

I need to get the rest of the details on the engine, but it's a full rebuild with nice components (all-roller setup) - and no it doesn't come with the headers but my SMI ones should be fine.

It dynoed 490hp and and I forget the torque but it was either 620 or 650ish, already been tuned and everything, they said they'd have the boat running in a weekend. :propeller:


03-22-2012, 05:37 AM
That looks similar to the last engine that I had in my 22C, Sea Demon carb, roller rockers, etc. that was also dyno'd at 490 hp. Stock or similar exhausts work just fine. As fixx can tell you from my postings, be very careful with the breakin and once broken in, don't run WTO for extended periods. In fact since mine has been known to "fly" I have a rev limiter on my new engine just in case ;-). Those loose pistons can ruin your day!

03-22-2012, 08:45 AM
That's funny that they both put down the same HP - what was done internally to yours? That's a good point about coming out of the water - my last boat had 270hp (ahem.. 2 stroke jet boat hahaha) so this will be a new problem to me. ;)

He said it's got a top of the line ignition system on it, so hopefully it's got the extra gray wire to program the rev limiter on it - my old one was a nice Pro Billet MSD as well but didn't have that option. :confused:

I just noticed yesterday after putting the drive down that my trim indicator doesn't work. :( I'm good w/ electrical but I'm worried the signal wire is buried in the drive somewhere.

What else would I run into problem-wise on the install? I'm trying to factor in extra costs since I have bad luck with my cars generally (stupid job turns into a fiasco) but at this point I'm thinking the oil cooler is the only thing I really need to look hard at / inspect / replace - the boat has a through-hull water pickup w/ belt water pump so I don't have to worry about the impeller or anything.

03-22-2012, 09:05 AM
There are a lot of much more qualified folks on this forum to answer your questions than me...my expertise seems to be in blowing motors up ;-) In fact if you want follow my sagas, just do a search for "Blown"....

03-22-2012, 02:20 PM
Forgetabout fixing the indicator....just trust me on this.

03-22-2012, 04:06 PM
Forgetabout fixing the indicator....just trust me on this.

Sadly, this is probably correct. But just so you know, the indicators are pretty easy to get to, mounted on either side of the gimbel housing. (You're running a Bravo, right?) Sort of a little black disc about 2-3" in dia. 2 screws hold them on as I recall. One side is the trim limit; one is the indicator. Can't remember which is which off the top of my head.

joseph m. hahnl
03-22-2012, 07:55 PM
personally before I even thought about a turn key crate motor. I would disassemble the engine and see where it's at. Rings, bearings ,and gaskets sets come fairly cheep. worse case seasoned block.All and all it adds up to way less then $5,000. My Minx was dropped and the exhaust pipe filled wiyth water. My mag had sea water in it for 5 yrs .my heads looked just like yours #4 cylinder was full of sea water as it was in the exhaust sequence.
A rebuild kit new heads and this will be season #7:tongue:

so lets do some math 2+2 =? that was too easy:wink:! lets try this a stuck valve that is an exhaust valve running at plane with no power equals what? a motor full of water. before we all jump in worse case, lets just look at what's there first.

trim senders are easy unless the SS screws break off from being galv coroded to the alum. then it's time to drill and tap new holes:frown:

03-22-2012, 10:06 PM
joseph m. hahnl , thanks for the advice - this was my exact line of thinking initially - especially with the water in the oil, however maybe the 80 degree weather (2 months early) has gotten to my head.

There are some problems with the 2+2 math you speak of.

First of all, "inspecting the motor" as you state, comes at the cost of taking it somewhere and having the hatch removed/propped, engine pulled, etc. - no one nearby can do this, so transporting the motor back to a location where I can inspect it is a logistical nightmare, plus anything after that sucks too. Either a) it's dead internally, in which case it's trash and I need a new motor anyways, or b) I work on it and have to transport it back and install again (now reached 100% of labor required for new engine) plus the parts and machining time.

This new engine runs the same labor costs install-wise, MINUS all the time and labor for taking the things apart and piecing it together.

Then I still have the issue that it wouldn't be a performance motor - replacing it with stock (worn/pitted) vortec heads? ..and the alternative being performance components and adjusting/tuning would land me at the same cost as this new motor, PLUS an extra month or longer for parts, machine work, installing, tuning, and putting it in the boat.

zelatore - okay I won't take your advice on the engines then hahaha, but I'm still curious about the trim indicator everyone!!
..and no, it's a late-generation OMC King Cobra (cone clutch, with the larger upper case) - can't see much around the gimbal area.