View Full Version : Cook book 454 rebuild and and h.p. increases ????

12-11-2011, 10:48 AM
Hey Guys,

I thought I might start a new thread here. Thanks to all those following and advising me on the seized engine and/or sterndrive thread.

I still haven't got to the bottom of that one yet. The motor will not turn yet ...why I do not know but I'll get to the bottom of it.

The engine is a 454OMC King Cobra '93 model showing 365 hours.

I'm going to pull the motor and drive anyway and go through them this winter. ...waiting for the manual on the drive hopfully no suprises with the drive.

I've got access to an awesome machine shop that I can pull the boat into lift the engine out lower on to my truck and then bring it over to a buddies shop where we will tear it down and figure out what we've got and then determine where we take it. +we can fabricate all kinds of cool stuff if we need anything made.

So I'll be doing the labor myself with the help of some friends and of course any of the tools and expertise from the machine shop.

I need to read all I can and figure out what the proven cook book recipes are to get this thing reliable and put a few more ponies into it.

I am thinking something over 400 h.p. and less than 500 h.p. ...needs to run good have great throttle response and sound awesome. Top speed ...not concerned for anything more than bragging but I suppose but something around 70 or a bit north of that would be nice. (and I also told my wife I wasn't buying an 80mph boat:cool:) I haven't ruled out a reman long block but not really sure it is necassary. I'd like to do this as efficiently dollar-wise as possible but absolutely make sure that it gets done right.

Anyone that can point me in the right direction? Good threads to read? Books? Experience? good and bad...

I'll keep at the seized engine for a bit and let ya'll know what I find out and if I can get it to light off but I still think the boat will be down for the winter but ready for the spring with a deep growl coming out the exhaust.


12-11-2011, 11:04 AM
I'm not the guy with the answers, but it seems to me there was a pretty extensive thread about this recently if you do some searching. As I recall, a lot of the answer (to hotrod your 454 or don't?) depended on what the internals were. In the Merc world, I think that basically correlated to:

IF low-tuned 310-330 horse, it probably has weaker internals you may not want to use, so consider selling it and start new.
IF 385 horse with good internals, you might want to keep it and start tweaking.

That's my best recollection of what people were saying. (If you find the thread, it may help to link it into a post here to save time for others who may share their expertise.)



12-11-2011, 11:29 AM
I'm in the same predicament, and after corresponding w/Buizilla, a good solution might be a new GM Gen VI short block w/all forged internals. If you have large oval port, or rectangular port heads and the appropriate intake manifold, it might be an affordable proposition. But good heads will be important.
Or a new GM Gen VI long block.
Anyway, they are a lot more affordable than you might think.

12-11-2011, 11:49 AM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

...yes seems to be tough decisions. I have no idea what I have at this point other than it is a 454 King Cobra OMC Spitfire ignition with a carb.

Like I said labor is not free because it does take time but I won't have to pay anyone other than beer... I've got myself and some pretty good hands to help me.

The Gen VI may be what I ultimatlely decide to do but need to weigh options. It seems some head work, new bearings, rings ...maybe a minor bump in compression and perhaps a cam with the correct specs should be easy cheap reliable horsepower.

12-11-2011, 12:29 PM
a Gen VI 502-502 crate engine is a GOOD move..

in George's case, he has to use a cast deep 2 piece rear main oil pan setup

his is going to be a little harder to figure out, for a crate setup

12-11-2011, 06:25 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

So If I want to simply do a reasonable rebuild with easy performance enhancements to the 454 what should I budget and where is the money wisely spent?

What should I plan on budgeting if I go with a 502 crate? The 454 that is in there is raw water cooled and I want to change that on this next go around no matter what I end up doing so I guess there are some extra expenses there too.

I am not new to boating just this side of it. ...spent lots of time (and money) playing with sailboats over the years (still do). ...so not going into this completely blind.



12-11-2011, 06:52 PM
step 1 is to get it out and dissasembled first, inventory usuable parts, and what was there to begin with, for future compatibility

then the budget talks will come into better focus

12-11-2011, 07:03 PM
that sounds completely reasonable

12-12-2011, 01:16 PM
If you are reusing the block make sure it was Tanked first and super clean before adding a FWC setup. If not the rust particles will clog your system.

12-12-2011, 02:48 PM
What is "having it tanked?" Some sort of galvanic treatment like they do with old cannon and such they restore from wrecks? To de-ionize?

12-13-2011, 01:11 PM
"hot tanked" is what we used to call it. Most machine shops do (did) it. Basically chemical cleaning by submerging the whole part in caustic cleaners. Hard to find places in CA that do it for enviro reasons; not sure about the rest of the country. Pretty much gives you back as close to a pristine part as you can get though. I used to do it all the time on old car blocks during rebuilds and they came back bare metal and ready to go. You do want to give it a decent bath with plain soap and water before painting it though just in case any chemicals are left over that might cause paint to not adhere well.

I have no idea what the actual chemicals are...but if CA doesn't like them, you know they're good. :wink:

12-13-2011, 02:12 PM
Yes Hot Tank is what we call it formally. I thought you motorheads would be familiar with tanking your block & heads. They look like aluminum when you get them out of the tank(big dishwasher). Whatever you do, don't tank your hood hinges, can't get the grease back in them.

12-13-2011, 06:32 PM
I have had many engine blocks & heads "Hot Tanked" over the years.
It does a very good job of cleaning up the cast iron/steel parts~~~not Aluminum however.
This process may do severe harm to aluminum castings.
With aluminum you must keep the total cleaning time to a short time period.

It's best to let the cast iron/steel parts sit in the hot tank overnight if at all possible.

The "Hot Tank' does not de-ionize the salt/sodium chloride salts from the iron castings that were exposed to saltwater however.
They do this de-ionizing process with cannon & other iron/steel parts recovered from shipwrecks that have been exposed to salt/sodium chloride salts for decades/centuries.

De-ionizing takes many months or years; and you must pass a DC electric current through the cast iron/steel parts.
It works just like reverse electroplating with a cathode metal connected to one side and the iron/steel parts connected to the reverse DC polarity.

If you do hot-tank your block remove all water jacket core plugs & oil gallery plugs for best cleaning of these inside block passages.
Some small oil gallery plugs are almost impossible to remove at times.

All your pressed -in camshaft bearings will be ruined by this caustic hot-tank , or engine washer cleaning solution.
Press-out your old cam bearings first~~~
Then hot-tank the block.
Press-in the new cam bearings after first rinsing & drying your cleaned engine block.

12-13-2011, 09:49 PM
anyone have a thought or two to share about a kit like this?

Scat #942-1-42360BI4340 Forged Rotating Assembly 489ci
Pistons: Dome
Bore: 4.280"
Stroke: 4.250" H-Beam Rod: 6.385"


12-14-2011, 01:48 PM
JayZ...be VERY carefull with automotive stuff and marine stuff. Even though it might say it's for a marine application, does not mean it is compatible with your exhaust, etc. When going exotic you need to find a great marine mechanic or buy a crate engine. There is a reason why a Merlin, Teague, or Mercruiser racing engines cost so friggin much compared to a car.

12-14-2011, 02:02 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]Got it on making sure it is up to marine standards. ...not going to jump in head first. I am trying to learn as much as I can here on this board and elsewhere. You notice I titled the thread "cook book" 454 because I know this has been done before and there has to be tried and true methods to rebuild the 454. The kit I posted has a scat 4340 Chrome Moly forged Crank, looks like quality rods similar to the carillo rods that went into my Porsche 911 track car and forged pistons. ...I don't think I want 9.7:1 compression though and if I end up building a stroker motor like this (489) I think I'd like to be closer to 9:1 C.R. Thanks,JZ

The Hedgehog
12-17-2011, 02:37 AM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

Not sure about the Merlin, but there is a good reason that Teague and merc racing cost more,and they are worth it.

12-17-2011, 11:18 AM
What are you all talking about, “marine parts”? There is no such thing. Everything was designed for cars or trucks then adapted to the marine world. A 7.4 Mercruiser is the same motor they use in GMC trucks and for that matter, back up generators, farm water pumps and a host of other stuff. Same parts, same steel, same castings.
There is some folks that will upgrade these motors like Merlin and Teague but they are still all auto parts. The only motors that were designed from the start to be boat motors are outboards and for the most part these days they take hopped up car motors and stick them on end for outboards.
Don’t get me wrong, there is marine parts. Like raw water pumps, Alt cases, starters, etc. But these are bolt on’s. A BBC is a BBC. Longevity all depends on the quality of machine work, parts and labor to build it. The only internal part I have ever bought from a “marine store” was a reverse rotation rear main and timing chain cover seals. Everything else over the decades has come from Northern Auto, Summit, Jegs, etc, etc.

12-17-2011, 11:36 AM
I was trying to think if there were any exceptions to the post above, about everything but the bolt-ons being automotive, not specific to marine. Two possible things popped in my head.

One was cams. Not the manufacturing process or materials, but simply that there were distinct marine grinds versus the mostly automotive ones. And maybe some that could work either way, depending on the application.

The other was valves/heads. I thought there were some marine valves/heads that used different materials from the automotive world. Don't remember seeing anything compelling about exactly why. And heads are also, arguably, a bolt on.

Is there anything else in the internals that's clearly marine vs automotive?

12-17-2011, 12:22 PM
One was cams. Not the manufacturing process or materials, but simply that there were distinct marine grinds versus the mostly automotive ones. And maybe some that could work either way, depending on the application.

The cam grinds are there, I know I researched a Mercruiser cam to find out and found the exact same cam for a Chevy pick up. It’s selection, yes the after market builders pick better cams (and some even grind them just for their set ups the same a race car builder would) but in most cases no matter what the specs are I bet it can be found at an auto store. Sadly all Flat Tappets cams in general are getting harder to find because they are not making the billets for some reason. But again roller cams are plentiful. For that matter I will be installing a “Merc 420” cam in the next motor I build………it’s from Speed Pro.

The other was valves/heads. I thought there were some marine valves/heads that used different materials from the automotive world. Don't remember seeing anything compelling about exactly why. And heads are also, arguably, a bolt on.

It’s not that they were built for marine apps. It’s that they just worked for marine apps. Take a set of Chevy / Merc 7.4 heads. The peanut port heads were designed and used for big trucks for more low end torque and emissions standards. What needs low end torque more then a boat so they got.
Again don’t get me wrong. You have to know what you are doing when you build any motor but if you know what they do (not saying you should research on the web every and any motor build combo you could ever want and exactly copy it or anything) and realize that you will have to take it a machine shop and pay them some money to do the things you can not but it can be done and for a lot less. But again though it’s all about the auto parts they or you select.
And I would like to exclude before it comes up;
A custom built race motor for a boat is not the same. The same as a Nascar team would not buy their parts at the local anything either.

12-17-2011, 12:54 PM
Good point. And very interesting about that available production truck cam matching a Merc cam. It would be REALLY interesting to see a list of the cams for the full product line of Mercs and Volvos, and an indication of whether each is an available off-the-shelf automotive/truck cam. And if so, what the automotive use is.

As far as valves go, I did some reading in the last 10 minutes and I already think I see your point. When I read between the lines, looking past all the "marine" marketing, the various features I see on "marine" heads seem to actually be "high performance" features. Materials that are more resistant to heat, etc. Inconel valves, for example. I see them in lots of "marine" uses, but I gather a lot of cars guys with forced induction call for them. Sounds like most if not all of the "marine" thing is really about motors that run a lot higher percentage of hours under continuous heavy load.

12-17-2011, 01:06 PM

Here is a list of casting numbers. Not a one is listed as "marine" but a ton of them have been used by the marine industry for ever.

12-18-2011, 02:57 PM
f_inscrenname gets it. From what I have seen there is nothing special about "marine" cams, valves, etc. You just have to make sure the overlap and LSA will not allow reversion. Look at a Merc 525 cam, it's nothing more than a Crane 741 with a 112 LSA. LOTS of people run the 731, 741 and 761 cams in the marine world with excellent results. If you want to get more aggressive you just have to dump the water in further away or run dry exhaust. And you obviously want a cam that will give a good, flat torque curve for acceleration and getting on plane. Not a concern in a drag car with a 3500 stall converter. Since marine motors always have extreme loads and tend to run high rpm extreme duty valve are a must IMO. It's all about the right combination of parts and GOOD machine work. Being .0010" off on main/rod bearing clearances may never pose a problem in a car/truck. But on a marine engine that may run 5000 rpm for 10 minutes at a time it could be a big problem.

12-18-2011, 08:27 PM
Well the engine is out and dissasembly is moving along. It had two seized pistons...

For you viewing pleasure or displeasure the engine is pretty ugly :

12-19-2011, 12:16 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

Yikes that is pretty ugly! Depending on the damage done it may be better to start with a fresh Gen VI short block.

12-19-2011, 02:08 PM
If the oil was clean you should be able to get away with the crank which will save you a few quid. The block can always be resleaved. Won't know until you get it all apart and hone those cyls to see how they look. Then again refer to the post above.

Lastly...what I meant on the previous page was you need a mechanic that knows marine. I have seen/owned what a "mechanic" has built for a boat, bad-ass for about 15 hours. Just make sure he knows what he is doing. If not sure then buy a crate engine and have him hook it up.

12-19-2011, 03:01 PM
Not sure which direction I'm going yet but if the block checks out anyone care to share thoughts on this recipe or add to it?


Part #

Engine (original block, 489ci kit)
Part #

MSD Marine Distributer
$ 295.99

Edlebrock Aluminum Marine Heads
$ 1,799.99

MSD Marine Ignition
$ 381.99

Valve springs and retainers

$ 100.00

MSD Coil
$ 47.99

Scat 489ci crank, rods, pistons, bearings
Scat 1-42305BI
$ 1,812.99

Edlebrock Marine 750 cfm Carburator
$ 531.99

Cam, lifters, and rockers

$ 600.00

Edlebrock Performer RPM Manifold
$ 219.99

Gasket kit

$ 200.00

Aluminum water pump

$ 192.00

Engine cleaning and boring

$ 300.00


$ 200.00

Timing chain

$ 100.00


$ 200.00

Oil pump

$ 60.00

Cooling system

$ 1,100.00

$ 3,169.95

$ 4,972.98


$ 8,142.93

12-19-2011, 03:16 PM
This one is for a 454,

Started with;

*1986, MIE/340 (7.4) 454 Big Block

Dip it and hone the decks and cylinders (the cylinders did not need to be cut and are standard bore)

Block was detailed with all casting debris removed

Stock seasoned crank (also cleaned up)

Reconditioned connecting rods

ARP Rod bolts

.210 Domed Speed pro pistons and pins. (They should give me 9.38 to 1)

Molly piston rings

Federal Mogal bearings (cam, main & rod)

Cloyes true double roller timing chain

Moroso Chevrolet 454 Stud Girdles #6729 BBC

Crane #132561 hydraulic cam--Duration Advertised: 298° Intake / 306° Exhaust Duration @ .050'' Lift: 228° Intake / 236° Exhaust Valve Lift w/1.7 Rockers: .530'' Intake / .551'' Exhaust Lobe Separation Angle: 114°

Crane #99277 lifters

Comp Cams High-Tech pushrods #7954

Completely refreshed Chevy 14096188 heads / 454 Open / 118cc / 3angle valve

Comp Performance Valve Springs #911-16

Pioneer head bolt sets

ARP 1.90 rocker studs

Norris S/S 1.7 roller rockers

Melling H/V oil pump

Melling HV oil pump shaft.


JEGS 15951 - Mechanical Fuel Pump

Pro Comp Ignition

Pro Comp distributor

Super Stock coil

8mm Accel Hi performance wires

New single wire alternator

Mini (gear reduction and fully marine) starter

Edelbrock 800 carburetor

12" aluminum, oval air cleaner (with K&N filter)

Brass freeze plugs

Stainless steel bolt set

4” Stainless steel risers

GLM aluminum exhaust manifolds

Sherwood motor mounted raw water pump.

This one is to make it a 496,

*1987, MIE/340 (7.4) 454 4 bolt main Big Block

Dip it and hone the decks and cylinders cut .060 over

Block was detailed with all casting debris removed

Scat 9000 Crank 4.25, 496 stroker

Scat 26385P - 6.385 in. Connecting Rods - Bushed -I Beam Forged 4340 steel

Howards Cams 120255 - Max Torque Retrofit Hydraulic Roller Camshafts, Hydraulic Roller Tappet, Advertised Duration 288/294, Lift .585/.610, 112 L/S

Howards Matching Valve Springs 98636 - 130# / 330#

Cloyes Gear 9-203 - Cloyes Wear Plate, 031 in. Thick,

Maxspeeding Hydraulic Retrofit Roller Lifters

Probe 496 Dome Top +18.0cc - SRS Piston Set

Clevite 77 Cam Bearings

Federal-Mogal 4400 M20 Main Bearings

King Engine Rod Bearings CR849HP

Cloyes true double roller timing chain

Mahle - Plasma Moly Coated piston rings

Melling 10778C (Anti-Cavitation) oil pump

Melling HV oil pump shaft.

New Harmonic Balancer

Rotating Assembly Fully Balanced

Comp Cams High-Tech pushrods #7954

Completely refreshed Chevy Heads 14096188 / 454 Open / 118cc / 3angle valve

APR head bolt sets

ARP 1.90 rocker studs

Norris S/S 1.7 roller rockers

Seal Power Gasket set


Pro Comp 2752 Fuel Pump

Pro Comp Ignition

Pro Comp distributor

Super Stock coil

8mm Accel Hi performance wires

New single wire alternator

Mini (gear reduction and fully marine) starter

Edelbrock 800 carburetor

12" aluminum, oval air cleaner (with K&N filter)

Brass freeze plugs

Stainless steel bolt set

4” Stainless steel risers

496 MerCruiser exhaust manifolds with Tall Risers

Sherwood motor mounted raw water pump

The Hedgehog
12-19-2011, 06:03 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

Great statement.

There is a reason that Teague stopped carrying crate engines.

12-19-2011, 06:15 PM
It appears that this was another low hour engine that was ruined by internally leaking exhaust risers/manifolds~~~as I first suspeced.

Countless otherwise good engines have been wrecked by internally leaking exhaust risers & manifolds.

If you have a boat engine that is saltwater cooled and it's center risers & manifolds are more than five years old , despite low engne hour usage time, ~~~
Check them out by removing the riser from the lower exhaust manifold.~
Or~~~Better yet just replace them .

They may very well be leaking internally just like the above pictured engine.

I suspect this engine block & crank can still be saved by a machine shop re-bore.

Good Luck ~

12-19-2011, 06:41 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

Yes, I think the P.O. just used the boat then put it away until he couldn't anymore...

12-19-2011, 07:50 PM
Pressure check block before and after cleaning and look closely at heads between valve seats. Big blocks like to hairline crack there.
You might be better off starting with a long block, Machine shop work adds up pretty quick .
I did watch a couple of mechanics at a local marina rebuild a big block only to find out it had a couple of pin holes in the block that leaked into the oil on the first start up.

12-20-2011, 11:56 PM
My 1994 22C I bought in August actually had the 94 OEM manifold/risers. I just bought new GLM manifolds and reused the Merc SS risers but when we removed them they were actually still OK but "starting" to leak. If I did not buy the boat and the PO ran it next season she would have been toast which would have been a MAJOR shame. I check my manifolds every year in FL. $20 worth of gaskets and your hour is worth an engine in my opinion. For you Northern people, PLEASE check them EVERY spring.