Im working on a project with 454 330hp engines in aŽ 32 pachanga.

Both engine has bin totaly rebuild and should make 400 hp.
-bored .030 over hyper piston 9.3 CR
-990 Heads no porting
-Hi perf intake dual alu
-Stock exhaust
-Crane cam (420)
-Q-jet 750 Rochester
-Eagle steel crank
-3/8 Rod
-std oilpump

Starbord engine has broke down on the piston#8 #7 rod/crankbearing 3 times after rebuild. First time after 1 hour, secund time after 5 hour and last time after 7 hour.
It has bin carefully break in and only wery little WOT@ 5000 RPM.
Oil-pressure is 35 psi/65 3000 rpm until it break down with no warning at all.
I dont want this to happend again so please let me know if someone can tell me what possible can make this faliure.?
Ihave to mention both engine are build with freshwater cooling and run 188* watertemp. I dont know the oiltemp.

Sorry, Forgot to spel check

Can you post pictures of the rod bearings?

I would suggest that you start with this thread http://www.offshoreonly.com/forums/s...t=oil+problems

It could be that your oil is bypassing the filter and/or there may be a problem with your oil line routing.

I think so,they are in my work shop so it will be the first thing tomorrow if I can find all the peaces.
The bearings are totally turned around and splashed up between the rods in very sharp thin peaces. Small parts even went op in the lifter galley. And how they can come up there is unbelievable.....?

Very helpful info. The engines i work with is mark IV and a little different in oil bypass system if I remember right. But the starboard engine as broke down has stock 330 hp oil cooler. The other one has a aftermarket bigger cooler. That could explain why the other engine hold op fine.

But if it is so, is it the restriction or the high temperatur due to the small cooler that kills the bearing ?

The bypass on a gen4 is in the filter pad adapter, I personally chose to plug mine to be sure all oil goes to the cooler/filter.

High oil temps could be an issue.

Did you change oil coolers after each rebuild? Or change the oil lines to cooler first then filter?

I to have a Pachanga and 330 and learned this the hard way
Last time I ended up with a 496

Exactly..
I forgot to mention that. There is NO good way to clean an oil cooler after a bearing failure. Sounds like you should go with aftermarket cooler like the other motor or plumb the filter AFTER the cooler as 1BigJim suggests

Did not change oil cooler but clean it very careful with compressed air. But I didn't know that it could be an issue. The lines are super stock mercruiser route.
But witch one of the fittings on engine adapter is outlet?
On engine adapter, there is a straight line connected to the oil cooler at front fittings, from rear fittings on oil cooler to filter and from filter to engine adapter where it return with 90* fittings.

By the way, how fast can you go with your 496 ?