Engine damage / 440 RB

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360duster

360duster

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Hi Guys,

built some sb´s up til now, no B or RB engine. Could need some support, maybe more in later stages of re-assembly ;-)

my friend called me, engine of his 73 coronet station died recently. I disassembled it today, found one rod bearing 90% gone, crank and rod damaged, bearing material all over. According to him oil pressure was ok, no overheating etc. - he´s a control freak and checks his gauges regularely.

What do you think caused this? Engine ran smooth for about 3 years, just a cruiser with occasional strip fun (i think never revved over 5000 rpm). Engine has got around 20000 miles since complete rebuild by a shop.

I do not know if this will clean up at .020" under. Is it possible to go even smaller on the rods?

Thanks for info

Michael
 

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it´s number 8. The engine had some detonation because of too high static compression ratio (somewhere between 10 and 11:1, the original builder messed it up somehow (Block was decked before maybe?). I had to adjust the Timing very conservative to stop it from detonating under load.

Michael
 
I was going to say - I've had issues with 8 before because the vacuum nipple for the power brakes is there and it can go lean if the booster's leaking a little. You can also look at the backs of the rod bearings and the mating surfaces of the main caps. If you can post clear pictures of those we can tell you how bad it was detonating. That's more than likely what killed it.
 
I would probably get the big ends resized also as a precaution in case they took a beating so to speak...just my opinion tho....
 
I'd replace both rods on that throw and have them all checked.
 
I am not getting these oil lines in the valley ? To me that is taking oil away from bearings where Mopar needs it the most . We put restrictors in the rocker arm lines to cut back the oil going there. Chevys love oil in rockers. Mopar love oil in bearings, lots of good oil !
I am just refreshing a 496 wedge after 6 years on the street and strip. This motor has hundreds of passes on it. The reason for refresh is it cracked a sleeve when a head gasket leaked and number two hydraulic locked.This motor was spec'd out by Dave Hughes of Hughes Engine. It is 13.4 CR running on pump gas 94 octane with no additives and 32 degrees timing. Dyno 735 hp 700 torque. Crank is mint condition,rods and Pistons going back in.New oil pump,rings,all bearings and one new sleeve.We only use Domar oil filters sold by Hughes Engines. They have No Relief Valve ! All other filters have relief valve which on cold start up Cold oil temp. Pushes valve open and all the unfiltered oil goes straight into the main bearings,rod bearings then on to the rest of motor. My current motor is a 572 wedge going into 3rd year is getting valves adjusted and fresh Joe Gibbs oil that's it. If you go to Clevite bearings web site they will show pictures of failed bearings ans have a write up of causes. Very interesting !
 
Measure the rod compared to others, just because it's shot peened and magnafluxed doesn't mean it's not stressed inside the rod. Been there. Best to buy a virgin rod instead of use 40 year old parts. You'll be money ahead. My .02.
 
i found out the original builder put in KB 237 in .040" oversize....these have +5cc, now i need to get an information about the cylinder head volume to see the true compression ratio....have no good feeling.

Michael
 
Heads are 452 casting, piston 0.031" over deck, .051" compressed head gasket. the heads are somehow worked to gain head volume. Tomorrow i'll take pics from the rods / bearings. It seems that the block did not suffer...

michael
 
"piston 0.031" over deck"
There's your problem. He probably knew that was a mistake if he enlarged the chambers and used that gasket. Have the shop take .020" off the top of the pistons and use emery to smooth the machining edges if that's not done already. The look at the camshaft, then the timing and carb's fuel curves. The problem is it's in a wagon. In something easier to move it probably would not have been a damaging issue.
 
Thanks at all for your help, i appreciate it very much.

Moper, that´s what i think, too. I just saw the heads are also resurfaced, don´t know how much....must be cc´d to get the info.

Camshaft is a comp XE268....i´d choose sth. a little bigger to bleed of some dynamic compression. Would this be a step in the right direction? Timing is limited to 32 or 34° total, he used the best available pump gas over here.

I´m also concerned about the rods generally. To me it seems they are not round anymore, see pics from the bearings.....what do you think?

Michael
 

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