Crankshaft opinions

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CaliTrav
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Crankshaft opinions

Post by CaliTrav »

Hi all,

So I finally got around to dismantling the "spare" 1098 I had on the workshop bench. (Shameless plug - to make life easier I got an engine stand and an adaptor plate from JB fabrications... it screws into the oil filter housing and alternator/dynamo mounts, I can very much recommend for something to make life easier)

The engine code suggests it was originally from a MkII Austin A40. At some point it found its way into a Minor that was bought for spares as a beyond saving example a year or two back. It was painted gold on the cylinder head and rocker cover, but the code doesn't seem to have been altered to suggest it was a genuine gold seal. That was curious!

Everything is now apart and having assessed the crank, it's not particularly oval but has worn quite a bit. It is just within tolerance of a regrind to take it to 0.040" undersize.

Just wondered what the approximate lifetime of it would be doing this vs. sourcing a better condition one, if anyone knows? Eg, 50,000 miles before needing to regrind. Really just trying to assess whether it's worth persevering with this crank or looking for a better one, in terms of longevity. If even at the limit for regrinding it's got a good shelf life then I might persevere with it.

As for the rest of the engine... I'm undecided. I don't actually have a car for it to go in, so I could keep it as a "known good" spare once it's sorted, sell it, or find a car that needs an engine... that's the option my wife is least keen on!! :lol:
philthehill
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Re: Crankshaft opinions

Post by philthehill »

The engine may have had a cylinder head off a gold seal engine. 'A' Series engine parts get swopped around as you have found with the engine assy.
As regards a 0.040" regrind - there is nothing wrong with a 0.040" regrind in that it is no different to a 0.010" regrind. The reground crankshaft will be perfectly alright and serviceable. The length of service depends on the quality of servicing and frequency of oil and filter changes.

oliver90owner
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Re: Crankshaft opinions

Post by oliver90owner »

I would say “If in doubt, regrind it”.

‘Not particularly oval’ does not make me particularly confident in the assessment. The crank bearing life can also depend on other parts of the engine being within spec.

I very much doubt, from your comments, that the engine would be good for another 50k miles.

Has the engine run since you have had it? A good overhaul of the remainder of the engine (rebore and head?) might well be more than the iffy crank could cope with.
CaliTrav
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Re: Crankshaft opinions

Post by CaliTrav »

Re. The measurements, taken vertically and horizontally several times with a vernier.

What that showed was 3 of the crankpins were worn but not oval, though one was definitely oval. Two of the journals were worn but not oval, but the middle was.

Because they were all worn to different amounts anyway I figured a regrind would sort any ovality.

The engine has not run since I've had it. I'm thinking about rebuilding it "properly" (eg with new or reground/rebored/etc parts) so that it's to spec. I was just seeking advice on the crank - I could use it with the max limit of regrind but wondered if there was opinion on here that said don't bother get a new one, or yes it will be fine!
CaliTrav
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Re: Crankshaft opinions

Post by CaliTrav »

Re. The measurements, taken vertically and horizontally several times with a vernier.

What that showed was 3 of the crankpins were worn but not oval, though one was definitely oval. Two of the journals were worn but not oval, but the middle was.

Because they were all worn to different amounts anyway I figured a regrind would sort any ovality.

The engine has not run since I've had it. I'm thinking about rebuilding it "properly" (eg with new or reground/rebored/etc parts) so that it's to spec. I was just seeking advice on the crank - I could use it with the max limit of regrind but wondered if there was opinion on here that said don't bother get a new one, or yes it will be fine!
philthehill
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Re: Crankshaft opinions

Post by philthehill »

I would suggest that a Vernier gauge is not accurate enough to measure the crank journals accurately. Journals should be measured with a micrometre.
You will be very lucky if you can find a new crankshaft.
The best you can hope for is a used crankshaft with standard journals in good condition.
Most crankshafts offered from the Minor parts suppliers have had a minimum of a 0.010" regrind.
Even I have to use a crankshaft with a 0.010" regrind as new ex factory 1275cc Midget crankshafts are not available.

CaliTrav
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Re: Crankshaft opinions

Post by CaliTrav »

Well yes... New to me :D
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