Big wing sump conversion – questions

Road-race engines and ancillaries - general discussion
Guy Croft
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Re: Big wing sump conversion – questions

Post by Guy Croft » Thu Jan 31, 2013 12:10 pm

Bearing are by far the most common cause of failure - the oil will be full of debris if it is that.

What about the oil pump relief valve setting?

Usually bearing failure is accompanied by rattling and stuff coming out the breather..

G
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hudsonhenry
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Re: Big wing sump conversion – questions

Post by hudsonhenry » Mon Feb 04, 2013 10:22 am

I think we are getting closer to the cause of the low oil pressure. a clearance of between 0.150 and 0.125 on this main when it should be 0.025 -0.060!
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Its the only one I've taken off so far but there was no knocking so perhaps its only this one.

Will post up some pics of the whole car soon.

Urbancamo
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Re: Big wing sump conversion – questions

Post by Urbancamo » Mon Feb 04, 2013 12:00 pm

In this point I personally would tear the whole lower end to pieces and check what's wrong. Bearing clearance of that size and that scorched bearing will tell something is really wrong and needs to fixed.

I think folks in this forum won't disagree!
GC_25

Guy Croft
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Re: Big wing sump conversion – questions

Post by Guy Croft » Mon Feb 04, 2013 12:52 pm

Good work HudsonHenry!

Tommi you are right, because apart anything else, the whole engine will be contaminated with bearing debris..

G
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hudsonhenry
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Re: Big wing sump conversion – questions

Post by hudsonhenry » Mon Feb 04, 2013 10:44 pm

Checked all the mains and have the following clearances:

1) 0.150
2) 0.125 – 0.150
3) 0.125 – 0.150
4) 0.100
5) 0.76

Not sure why they get tighter towards the flywheel, any ideas?

They are all out anyway so its engine out and a strip down.

Luckily an fantastic book arrived today, looks like its going to be very useful...

Probably won't start the strip and rebuild until the end of June as we are about to have half the walls in our house knocked down. Still give me a chance to do some reading.

Guy Croft
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Re: Big wing sump conversion – questions

Post by Guy Croft » Tue Feb 05, 2013 12:41 pm

Tighter at FW end?

I don't know - and it may not matter - what does matter is ID'ing fundamental cause.

Let us have a photo of the crank when it's out, I can't remember if it's cross-drilled. Failure to clean out such a crank after polishing or grinding - invariably leads to rapid bearing damage - though I am not assuming it was..

G
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hudsonhenry
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Re: Big wing sump conversion – questions

Post by hudsonhenry » Tue Feb 05, 2013 8:10 pm

Guy Croft wrote:Tighter at FW end?

I don't know - and it may not matter - what does matter is ID'ing fundamental cause.

Let us have a photo of the crank when it's out, I can't remember if it's cross-drilled. Failure to clean out such a crank after polishing or grinding - invariably leads to rapid bearing damage - though I am not assuming it was..

G
The bearings look what I would describe as smudged rather than worn (I know its not a very technical term but the best I can come up with). Could it be that the bearings were just the wrong size and the clearances not checked when the engine was put together? There was only the tiniest trace of metal in the sump.

Will post pics of the crank once its out.

Guy Croft
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Re: Big wing sump conversion – questions

Post by Guy Croft » Wed Feb 06, 2013 1:16 pm

could be wrong bearings, yes

G
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