hi guys thx for the info on the big block heads.i tore the lower end down today and found the # 6 rod bearing was ate to s**t and the #8 rod isnt far behind. the mains all had copper showing in them. this motor has only 2 k miles on it.the back of #6 rod bearing it said standard on one half on the other half it said 0.10.do you guys think that was the reason it didnt last. and all the bearing materal got in the mains?and ate them up?.also its a 2 bolt main.how do i tell if its a forged crank like i was told it was.thx for any info:confused:

Yes, I would have to think the different bearings was the cause of the damage.
As far as telling if you have a forged crank: look at the rough material at the front part of the crank behind the snout and you will see the "casting mark". You know like when they pour metal in a case and when it cools down they split the case and take out the crank it will leave casting flash. If that line is about 1/2'' wide it is a forged crank. If it is narrow it is cast.
I hope you can understand this.

Edited: Narrow=cast
Wide=forged
Sorry I had it backwards. Thanks pdq67

yes i understand.i just went out and looked and the lines are real tite close together.so i guess it is a forged crank.other then the crank all looks good.double roller timing chain. no ridge at all in cyclinders got some water from sitting out side for 5 years in the #2 hole but cleaned up nice.turnes over real good.i hope i can get away with having every thing boild out and freshend up.i hope the crank can be saved

He's got it backwards.

Cast crank, narrow parting line.

Forged crank, wide parting line.

And a cast crank when hit w/ a small hammer when hung by a piece of wire will go "DONG" whereas a forged crank will ring like a bell, "DING"..

Who put it together and missed the bearing halves??? If you paid somebody, go back and make them eat it!!

pdq67

i freind of mine gave me the motor last year.he had a guy in medford oregon rebuild it for him about 5 years ago.he stamped numbers on all the rods to keep em in the rite order.the pistons have 0.30 stamped on them.they look like they have a dome on them with valve relief cut outs.the holes look good with no ridges.but the rod bearing are a mystery?what i dont understand is why is there 2 different bearings halves even near that motor.mabe clevite screwed up and put the wrong bearing in the package and the motor dude didnt catch it?thx for the info on the crank at least if its toast it wont be as big of lost

[quote=bikedude3;1038965]i freind of mine gave me the motor last year.he had a guy in medford oregon rebuild it for him about 5 years ago.he stamped numbers on all the rods to keep em in the rite order.the pistons have 0.30 stamped on them.they look like they have a dome on them with valve relief cut outs.the holes look good with no ridges.but the rod bearing are a mystery?what i dont understand is why is there 2 different bearings halves even near that motor.mabe clevite screwed up and put the wrong bearing in the package and the motor dude didnt catch it?thx for the info on the crank at least if its toast it wont be as big of lost[/quote

it is not unheard of using different bearing shells on select fit crankshafts.Typically an oem procedure and utilized by engine builders.

ok i didnt know that.thx

I'd think if that one bearing half was stamped 0.10 (recheck it, I'll bet it is .010), that the engine wouldn't have turned over at all. That, or maybe the bearing is stamped .001. If that particular journal was a little undersize, then both bearing halves should be .001 over, and not just one of them.

it is stamped .010.i would think both halves would be the same also.the other halve has std stamped on it

If one bearing half is stamped .010 and the other is standard, and the thing lived for 2000 miles, I'd have a serious look at that crankshaft. If the crank journal is OK, when that bearing cap got torqued down, it would have locked the motor up tight. Something weird is going on, or possibly a standard bearing got stamped as .010??? TIme to take it to a competent machine shop! Both bearing halves should be the same!!

Don't worry about the crank b/c I think you can buy up to .100" undersize bearings for BB cranks.

Suckers are tough as nails, even cast!!

pdq67

I replaced my Cast Crank with a Forged one last year in a 73 454 with 781 STD Valves heads. That cast crank has spun 6200rpm and a few missed shifts at 6500rpm lots of times since 1976 with Stock Rods and Cast Hyper Pistons and the crank still polishes with 600 Grit within Standard Specs. The only thing I did to the crank back in 76 was to have it Cross Drilled. I hope this very heavy Eagle Forging with SIR Rods and Forged TRW's and over sized valves will rev 7200 rpm and be as dependable as the OEM Cast Crank considering all the money I put into it for another 1000rpm.

PS: Topically my gear change is to short shift at 5500rpm with a Cast Crank but by the time you do it you at 6000rpm; so I recommend attempting to short shift at 5000rpm to get in before 5500rpm. It takes a lot longer to shut a BBC Down without sucking all the oil out of the pan then to Wind one Up - LOL

thx guys for the info.the crank journal dont look good.has a couple big ridges in it.im trying to get ahold of real good motor guy who can grind cranks down.im going to get the whole motor to him to have every thing boiled and cleaned real good.summits sells a scat cast crank for $229.would i be getting what i pay for with it?what would it take to make 500hp with this motor? thx guys

oh yea what does cross drilling the crank mean?what does it do?:o

Cross drilling ensures journal oiling every 1/2 crank rotation rather then after 1 crank rotation. Tends to keep the Crank Cleaner and Floating in Oil better at Higher RPM.

ok thx.