View Full Version : 454 Short Block

09-02-2011, 07:54 AM
With a little over 20 hours on it I managed to destroy my nice newly built 490 HP engine in my '88 22C.... think that the carb malfunctioned and pumped some gas into the oil, spun a bearing, locked everything up. Haven't pulled the engine yet to see what exactly happened, but tech suspects the block is holed since there is water in the oil. This will be a winter project, one that I just did last winter. Anyway, need some leads, tips, etc. on how we should proceed with this. I haven't started really looking yet, but just need the bottom end stuff. Top is great.


Just Say N20
09-02-2011, 08:40 AM
I ask this is the most "innocent" way possible, but how could a carb put gas into the oil?

09-02-2011, 09:03 AM
I will state this in the most innocent way possible > get another opinion on the failure,,,, your not going to hole a block from fuel dilution..

09-02-2011, 09:08 AM
Hahaha, good question, but the best that I can figure is that one morning when trying to start the beast it kept sort of starting, running like it was on 4 cylinders...barely, then started blowing smoke, sputtering, etc. I shut it down and called the tech. Problem was with the float in the Sea Demon carb, it somehow was causing the carb to dump copious amounts of gas into the engine that was not being burned, thus it was making its way into the bottom of the engine. He immediately changed the oil and filter to try to get the gas out. Then rebuilt the carb. No problem after that. But I think that perhaps the gas might have damaged the rod bearings on the crank. When the "event" occurred about a month later I had just gotten airborne at WOT which of course over revved the engine somewhat, and about 2-3 minutes later "Blam", an ugly sound that I now know only too well. This may not turn out to be what caused failure and I won't know until the tech takes the engine apart for sure. The way this engine was built it just should not have randomly happened...something had to cause it.

This is a brief description of the build on the blown engine: bottom end machined and assembled by Gardener Performance and are .060 over. This engine was actually built the first time with consulting help from Dennis Moore a few years ago and most of his setup is still there all that was changed was the induction and comp ratio. Hydraulic Flat tappet Cam... #'s are .510 lift and 226 deg. intake and 236 deg. exh. @.050 on 112 centerline. Roller rockers and Moroso heavy duty push rods...All forged internals Dimple rods with new SRP forged aluminum pistons. Heads are iron large rectangular GM's with inconel exhaust valves. Nice accesories. KE removable valve covers, new Stainless Marine crossover kits, Gill exhaust, Sea Demon 830's, Gill 10-12 Qt oil pans.

We shall see what happened when we pull it out in a couple of weeks.

09-02-2011, 09:20 AM
I will state this in the most innocent way possible > get another opinion on the failure,,,, your not going to hole a block from fuel dilution..

All opinions and "guesses" right now until the motor comes out and apart. BUT, it is definitely broken in a major way, so still need some ideas on a decent short block. I know that there are lots of places where one can buy them, but I would like either a "blank canvas" that the tech can build on, or one that already is built with plenty of marine "beef" on the bottom end. Got time, just need some ideas.


09-02-2011, 10:23 AM
What path does all that unburned gas take to get to the bottom of the motor? What is the effect on things further up, such as cylinder walls, rings, pistons, etc?

09-02-2011, 10:36 AM
I would think exactly the path that you described, but I am not a mechanic or tech, so I do not know. All that I know is that gas ended up in the oil after the carb badly flooded the engine... period. So, nuff of that, need to get some input on the short block question ;-)


09-02-2011, 02:34 PM
You probably did the same thing I did to my motor, except I did it with water instead of gas.

I don't think it was the fuel mixed with the oil that killed the bearings. More likely the engine had to try and compress unburnt gas which pounded the bearings and/or tweaked a rod.

Many, many years ago I had problems starting my car because it flooded excessively. Pulled the plugs and cranked the engine. Fuel came out like I had 8 garden hoses attached to it. Gave the cylinders a shot of oil and tried to fire it again. BOOM!! Blew both valve covers completely off the motor. :shocking: One stayed in the engine bay, but the other landed 15 feet away. Not really a related story. Just pointing out that flooding an engine can cause big damage.

What about the guy you bought the motor from? Didn't he have two for sale? Maybe you could get a better price on the other one and be on the water quicker (and cheaper) than rebuilding.

09-02-2011, 02:41 PM
If you pop a hole in your fuel pump diaphram and don't have a bypass line up to the carb, fuel will go past the diaphram and into the crankcase. If the bypass line is in place on the backside of the diaphram the fuel will go up to the carb and choke the motor out.

The fuel pump diaphram on the 350 in my 18C failed once and filled the crankcase with fuel until the motor stalled. I drained about 10 qts of fuel/oil mix out of the crankcase but the motor was fine. I had my bypass line plugged do to a new carb.

09-02-2011, 04:56 PM
Electric marine pumps have the pump drain line to the carb also.

09-02-2011, 06:09 PM
[ QUOTE]I had just gotten airborne at WOT which of course over revved the engine somewhat, and about 2-3 minutes later "Blam", an ugly sound that I now know only too well.

The way this engine was built it just should not have randomly happened...something had to cause it. [/QUOTE]

Not trying to be a douche, but it seems you have your non-random cause right there.
You just never know when that one over-rev will be the one to cause problems. I've missed downshifts in race cars, I've cavitated props on re-entry - scares the sh!t out of me that moments later I'm going to ventilate the cylinder case. But I've been lucky and never had it happen. A buddy of mine used the same engine builder as I did, same bottom end components, and within the first 5 hours of run time, puked a rod through the block. Data showed he had never even run to the limiter. Sometimes it just happens...

Phil S
09-02-2011, 06:11 PM
If I missed it in previous posts, sorry....but do you have a rev-limiter type ignition system ? If not, and you spend any amount of time in the air at WOT, I would certainly recommend going that route.

I heard that distinctive sound once, years ago, coming from an engine that I over-revved on an autocross course having missed a shift. It was an inline-6 and there were holes on both sides of the block big enough to put my fist through. Needless to say, I didn't take the field in G-stock that day. :bonk:

Sure am sorry to hear about your engine woes though ! Keep us posted.

Phil S.

09-02-2011, 06:29 PM
just speculation,,i wonder if the builder put new roc bolts in the rods,,if so and he did not use a rod bolt stretch gauge you may have streched the rod bolt when you over reved it and the nuts may have came off and you might of lost the cap to the connecting rod and thats what may have gone through the block.

when your tech gets it out have check the torque on all the rod bolts,they should be 65 psi..take pics and post the damage..

if its just the short block you may be able to get away withone of thease,,but have them lower the compression to 9.1..


ps,,pull a riser and make sure you dont have water in the manifold,,their will be little white spots in the black carbon.

09-03-2011, 10:44 AM
Fixx > will all of the other 454 parts bolt back to the 454? Maybe a dumb question. I sent them an email asking about their 502 product with the lower CR. Maybe another dumb question, but talk to me about the water in the risers... cracked/broken?

As always, thanks for your good advice :)

09-03-2011, 10:50 AM
Phil S > interesting question since I have asked my tech about something for my '87 Correct Craft. It has a 454 PCM stock engine that the factory states shouldn't exceed 4,400 rpm and it will easily turn a 1,000 rpm past that if you push it to WOT. Doesn't have much fancy electronics on it, pretty basic and my tech didn't seem to know of something that you could install to limit the revs.

Any thoughts on what could be used for the CC and/or the Donzi? WOT on the Donzi propped with a 25P Mirage + is 5,000 rpm, 4,600 rpm with a 27P Mirage. :bonk:

Phil S
09-03-2011, 04:44 PM
I'm sure there are others, but MSD makes a marine ignition system that has a built-in rev limiter. Just do a google search on marine ignition systems and you'll probably find others.

Phil S.

09-03-2011, 05:21 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

just wondering if reversion could have played a part of the engine coming apart..i would pull a riser and have a look to see if their were any water in the manifolds,if you compress water in the cylinder that is what could have broke the rod,,over reving could have caused it but you would of had to over reved it at 6000 plus rpms to do major damage..msd makes a inline rev controller which you would install a rpm chip that cuts out every other cylinder to keep it from over reving..this one can be hooked up to any ignition with a external coil..


yes your existing parts can be installed on any but a gen big block,,the bolts thread size on the front of the block may e 7/16'' or 3/8''.. you have a fuel pump on your block i think but the gen5/6 has the fuel pump mounted to the sea pump..

09-03-2011, 06:02 PM
The incompressible fluid problem was one of the things I was curious about when I asked about where the gas went. Could gas have done it instead of water? Anyone ever heard of it actually happening?

joseph m. hahnl
09-03-2011, 08:29 PM
I think your best bet may be a seasoned block from a junk yard and put all the forged stuff in it. I would bet that all that stuff is fine. More likely good than not:yes:. Gas in the oil can rub off the babbitt from the bearing. Once gone failure is eminent, Spun bearings & no oil pressure:frown:.I would think rod knock and an idiot light would have come on before the rod would break and come through the block.

I suspect inconel valves:eek: Personally not a big fan of multi piece valves.
This is one of those can opening topics:boggled:.But I never understood why anybody would want the valves harder than the seats.

09-03-2011, 11:05 PM
[ QUOTE=$originalposter]{$pagetext}[/QUOTE]

the velve takes more heat then the seat does and thats why ppl who build marine engines perfer inconel valves..
corrosion - and oxidation-resistant, nickel-based alloy. Its outstanding strength and toughness in the temperature range cryogenic to 2000F (1093C) are derived primarily from the solid solution effects of the refractory metals, columbium and molybdenum, in a nickel-chromium matrix. The alloy has excellent fatigue strength and stress-corrosion cracking resistance to chloride ions. Some typical applications for alloy 625 have included heat shields, furnace hardware, gas turbine engine ducting, combustion liners and spray bars, chemical plant hardware, and special seawater applications.Alloy 625 has withstood many corrosive environments. In alkaline, salt water, fresh water, neutral salts, and in the air, almost no attack occurs. The nickel and chromium provide resistance to oxidizing environments. Nickel and molybdenum provide for resistance to nonoxidizing atmospheres. Pitting and crevice corrosion are prevented by molybdenum. Niobium stabilizes the alloy against sensitization during welding. Chloride stress-corrosion cracking resistance is excellent. The alloy resists scaling and oxidation at high temperatures.

joseph m. hahnl
09-04-2011, 09:18 PM
Believe you me I Know exactly what inconel is:yes:

Exhaust valves are made from inconel 751. 35 HRC at room temp down to next to nothing as the heat goes up to 1100 to 1400. In other words they are for engines that are producing extreme heat all the time. like nitrous, supercharged or turbo'd. Not really needed for moderate use like a pleasure craft. So any way, I get the theory. If your going to use inconel exhaust valves buy the solid don't get muti piece valves

personally I'll stick with the solid one piece 21 4N stainless