warrenja1

iTrader: (2)

Hey all,
Just looking for some advice here. No.4 big end spun a bearing on the sap while on the dragstrip. Got the crankshaft out but it looked well worn (11.8 seconds on full load could do that I suppose!)
Sent it off to the machine shop anyway to see but they tell me it's bent by nearly 0.5mm!
I had another slightly scored one in the garage so sent it off for for a regrind. They tell me this was also bent but only by 4thou which they completely took out by an offset grind to 0.5mm undersize all over.

Got all the new bits needed last week so decided to start assembling this evening.
Start tightening down the main caps checking crank rotation after each. All goes well until the last one, no.5, where the crank gets much stiffer to turn.
I can still rotate it by hand but not as easy as expected. Loosening all the others and just tightening no.5 makes it free again.

Looks to me like it has to be either a bent crank or a warped block, although I'm assured crank is definitely straight. Anyone have any experience of this?
Would the old crank with such a major bend cause the block to distort?

Any opinions welcome.

Thanks

warrenja1

iTrader: (2)

Yea, didn't have time to plastergauge yet, although there's not much need to as I know it's definitely too tight.
It seems unlikely to be one specific bearing though as it was no.5 that made it tight, then loosening all the others made it free again.

escoskmv

i spun no 4 and bent my crank at 140mph, luckly i had a spair crank that turned out to be a good one so a set of acl race bearings and it all went back togeather with no probs. i would have thought your block is fine but its worth getting checked out and dobble check the crank.good luck with it mate

tabetha

Did the machine shop not check the crank after the shell spin ?
If they didn't I'd be having machine work done elsewhere, where they actual do give a shit.
tabetha

dangerous brian

Is it the correct main bearing cap? Wrong main bearing cap will do this.