I will take some pics of the piston-rod assemblies tomorrow.

I agree with Mike, looks like heat checking to me, a good std std GM fordged crank may be in order, and Randy we knew u pulled the bolt first. :party-smiley-004:

just fyi,gm bought the gen 5&6 cranks from scat.

couple of things...need to have a machine shop ck the crank for size/round and the rods as well, I have run into scat and other cranks that say factory balanced be totally crap and have a tuff time getting them to balance at all, can't imagine what they would be like run as is...backfiring had nothing to do with the bearing/vibration..good luck Rob

So a Kellog stamped crank is from Scat ?

when you see that shade of gray,,they're all from china.
scat cranks are usually alright,a touch on the high side but have been way better than eagle.

Yes, Im aware of that, but it didnt answer my question

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[QUOTE=Randy Nielsen;4160844 The crank was replaced & short block built 5 yrs ago then stored until last yr then everything disassembled cleaned up & reassembled, dyno'd now this.[/QUOTE]

I must have missed this.from the markings on the bearings,this crank/bearing clearance is a miss.
do you remember measuring this crank and adjusting bearing clearance.

yeah,I don't know that,,maybe RMbuilder can answer that

that is not what i said,i have never seen a kellog in a factory gm shortblock but anything is possible.

I've opened up 6-8 stock 502 Mag motors all gen 6 and they all had Kellog cranks in them, I was just verifying your post, back to Randy, the pics to me look like the rods got real hot, clearance issue like stated before ?? I think the dyno got all the run time out of this motor

i know that gm is scats biggest account but i guess they will go elsewhear to get what they need.the reason for my post was because every one i have had apart had a scat crank.

Geez how the hell can u gain this type of knowledge! totally jealous

Well, I took the crank down to the engine shop and Mike might be right about them using their own flywheel because he brought out a neutral balanced wheel to see if it would fit and told me another person mounted the engine to the machine. He is going to polish the crank & wants me to bring a rod-piston combo, the flywheel, & the balancer so he can recheck the balance. Hmm, I thought I paid for that already,, twice!! Gotta love it!! Either this is an innocent mistake or I got purposely screwed. I will look for part # on the bearings tomorrow, I forgot to look when I was taking pics.

well you learn something every day,i have a 502 in the shop right now and it is disassembled.i took a look at the crank and it is a kellog.

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Not for sure but it looks like INT an internally balanced crank and not a nuteral balancer

i agree,the engine is internally balanced and needs a neutral balancer&flywheel.randy,that crank requires narrowed bearings.do not reassemble it with regular bearings or it will be short lived.also,if you remove the bolted on counterweight from the balancer you will have the neutral balancer you need.

This engine is so screwy, as far as I know from personal experience this crank and this balancer ran fine on the dyno. The flywheel is suspect. If everything gets checked AGAIN in front of me so I can see it for myself, and I reassemble it with the correct bearings at proper clearances it should run shouldn't it? Apparently the builder in Omaha was a drunk monkey or something. I will not be sending him a Christmas card!!

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Randy I don't see any way this motor ran fine any time, wrong flywheel also, no weight to remove either, if the cranks OK then get the correct wheel @ remove the weight like Mike stated and you should be good. I think :eek:

ok randy,the bearings are correct and is narrowed ,the x indicates .001 extre clearance ,the h is a high perf bearing.those are good bearings and i use them a lot.as already stated the balancer&flywheel is not correct for internally balanced engine.

The shop says they are going to rebalance the crank, I have a new flywheel coming also new bearings & will reassemble myself. He showed me the balance being off so I will have him show me the balance again when he's done. He says the crank is off by about 1 1/2 oz.

i read your earlier post,,in order to get the correct ballance he neesd ewverything to determine the correct weight to ballance the crank at,,rods,pistons,piston rings and the rod bearings being used in the engine..i say he will be a little off and that harmonic ballancer,,find one that has a fixed weight on it,that one is not so good..

Everything is there so he could determine the weight for the Bob weights. As far as the balancer I will see what I can do. I really am sick of spending money on people's mistakes so I will look for one in my pile of parts. I can't believe I have to stand over someone's shoulder to make sure that what I paid for actually gets done!!!

Seems to be a lot of this going on in the marine industry, good luck

Thanks guys for the help & education. I will post what happens when I get it back together.

Got my parts back, re-re-re balanced crank, new bearings, new flywheel, &rebalanced damper. Anything special I need to do when assembling?

Who are you using????
PM me if you like.

Don't forget to replace your oil cooler before firing up your new motor. It is an easy step to overlook and could send bearing material through your new motor.

If memory serves correct when the crank is installed & mains torqued to spec it should turn without having to use a breaker bar am I right? I wiped down the bearing surfaces in the block & caps and the back side of the bearings with a clean towel so there wouldn't be anything under the bearings. Lightly wiped the crank & bearing surfaces so there was no dust or anything, set the crank and plastigaged the mains. I got .0010 on #1, .0015 on # 2,3,4 & 5. According to the merc manual I have they should be torqued to 110 ft lbs. The book says #5 is a little tight by .001. I removed the crank & decided to lube everything and try it to at least see how it turned. The problem doesn't seem to be with #5, it seems to be #3 that makes it drag & actually feels like something is egg shaped as it turns. I stopped there. With everything that has gone on I seriously considered a sledge hammer & toss the pieces through these shops front windows!!! Where do I go from here????

I would not trust plastigauge for a high HP marine build. That's something you use for the 350 you are rebuilding for your old pickup truck. You need to have a competent machinist check everything with the proper tools. Sounds like you may have a bent crank, main saddles out of alignment, etc. The old bearings would have wear patterns on them that would be the telltale for problems like this. Spend a little extra and get it done right!

Isn't that to tight for clearances? I believe mine are 0.0032" mains and 0.0027" rods.

That main tolerance is too tight. Something is horked. The crank should rotate very smoothly when installed.

This might be tough to hear, but are we ready to take this motor somewhere else ?

I am taking the crank & everything else to another shop then the block if needed. Here I go AGAIN!!!

Well guys, I got everything back again. The crank was turned .010 under on the mains. The line bore was checked & found to be ok. Mains measure .0025 on 1-4 and .0035 on #5. the crank turns free with .008 end play. I installed the pistons & have no side clearance on 1-2 rods all others are ok. Nothing was changed with rods or pistons, other than rod journals repolished & new bearings I can't see how that would affect side clearance unless the shop that polished their screw up screwed up yet again! The most recent shop did no work in that area because it wasn't requested by me. How did this F@#KING engine even run without completely tearing itself apart?

somebody not doing there job...no rod clearance at all ??

What bearings are you running and what crank is this? If you should be using a P bearing with a chamfered edge for a crank with a fillet and you try to install H bearings you will have no side clearance. I quickly glanced but didn't see which crank you are running.