Thunderstruck

Bearing clearances of .003 and higher on the rods/mains with a stock oil system will also produce the indications he is seeing. More bearing clearance allows more oil flow which requires more flow to maintain good oil pressure. There are too many restrictions in the stock oil system to get the volume to produce the pressure needed with big bearing clearances. He never actually said that he ever had "good" oil pressure. Could you verify you had good oil pressure to start with?

Other issues that could cause bad oil pressure could be lifter bore clearances, cam bearings along with the stuck oil pump relief mentioned earlier.

No way that motor would run 30 hrs with tight bearings that started out with good pressure and went down over time due to bearing wear.

cubicinches

This is 100% correct.

Can the OP confirm that the engine ever had acceptable oil pressure?

It's sounds likely that the engine was assembled with clearances in excess of .003". It is quite typical of most aftermarket crankshafts to have journals which are at or below the lower limit of the spec, which results in excessive bearing clearance when used with standard bearings. Often, .001" under bearings, or a combination of .001" under and standard shells is needed to achieve proper bearing clearance, or the main bores need to be align honed to the tighter side of the housing bore spec. A good question to the builder would be to ask him directly what exactly the clearances were at the time of assembly. If he cannot answer you difinitively, with any degree of confidence, it's time to go elsewhere.

As was stated, an engine with extremely tight main bearing clearance is not likely to have lasted 30 hours... especially in a marine application.

And.. not to side with the un-popular guy... but it is prudent to do a proper analysis of what has actually occurred before hanging the engine builder. 30 hours is plenty of time for an installation, plumbing, fuel, or tuning related mistake to destroy a properly assembled engine. I've seen it many, many times, and often these mistakes are still mis-construed and blamed on the builder. Again, the question arises as to whether the engine ever had decent oil pressure with the proper weight oil.

mike tkach

iTrader: (3)

practice what you preach,by the way,i still think you are a prik,and a stupid one at that,now

mike tkach

iTrader: (3)

i completly agree,but with the low oil pressure,one would not have to run it hard very long before the crank is scraping the bearings because the oil cushion is not sufficent to keep them apart,this is why i believe it may have spun a bearing,or two,and that is why i suggested not to run it anymore.

MILD THUNDER

iTrader: (3)

I'm not slamming the builder based upon low oil pressure. I was suggesting that a builder who tells his customer not to worry about almost 0 psi of pressure at idle, and 20psi on plane, is just fine, and run it.

Also, from reading some of the OP older posts, such things like a blown head gasket at two hours, 0 compression in cylinders, rockers not adjusted properly, etc.

I can only base my opinion of his builder from what I see. Blown head gaskets, 0 oil pressure, misadjusted rockers, and flat out bad advice to his customer. The OP said he has to have faith in this builder, because he's done engines for other's at his marina. Well, then why is he here asking for our opinions if he trusts his builder? Probably because he's sick of getting bent over. Can you blame him? We aren't talking a 1400HP blown solid lifter hi rpm engine here. We are talking about a 454 with a 1/4" stroker crank. Life shouldnt be this hard.

Heck, at this point, i'd probably wash my hands with the whole engine if it turns out to need major repairs. I'd get myself a GM 454HO crate engine and go pull my kid's in the tube. I had a buddy who went thru rebuilding and messing with his old 454's. He finally had enough of them just not being right. Ordered two of the GM crate engines, those engines are still in that boat with like 900 hours and going strong.

cubicinches

All very true statements, and if all of the aforementioned issues lie solely with the builder, it does certainly sound as if he may be putting his faith in the wrong guy.

With a lack of any noticeable debris in the filter, I'm banking on loose main bearing clearance right from the get-go.

EDIT upon re-reading some more of the story... and to your point about the builder... all high volume pumps come with the blue, high-pressure spring installed. Not sure who would install the low-pressure spring (which does not come with the HV pump, as the blue high pressure spring comes with the standard pump to be installed as an option) in a HV pump, and what's their reasoning behind it?

FIXX

iTrader: (2)

Got a ? on the build..

Did your builder use a 6.585 rod legnth for the 496 stroker,also ask him if he internally ballanced the engine which would require a 396/427 harmonic ballancer and flywheel,you cant use a external balllancer and flywheel on a stroker 496 and it must be internally ballanced..if he did not then find a builder that knows what to do when converting a 454 to a 496 stroker..

cubicinches

You mean a 6.385" rod?

Why can't a 496 be externally balanced?

mike tkach

iTrader: (3)

the op stated that this engine has an eagle crank,the last eagle crank i used on a build had journal sizes all over the place,i had to mix&match every bearing to get the proper clearance,i no longer will use an eagle crank,even for a low dollar build,just not worth the effort,the scat cranks i have used have had much more consistant journal dia sizes,and are priced about the same as eagle.on another note,the eagle h beam rods are very consistant on bore sizing,just does not make sence to my.

MILD THUNDER

iTrader: (3)

good points about the balancing FIXX. If the builder re-used the stock GM balancer and flywheel, you have a good leg to stand on when you call him out!