27 replies to this topic

[Spider]

I guess it isn't good news https://photos.app.g...PxoubKvgayWCZh8

 

OK, that looks to be 0.14 mm or 0.0055" to me !

 

Has it been re-ground ?  If not, this may just be the wear in the mains, they don't wear round, so maybe pop the crank out and check the diameters of the journals in at least 3 places around the diameter. If it's been re-ground (and from memory, it's not), then it has a bend.

 

While you are set up this way, place your DTI on the Crank Nose and check here too. That's not normally subject to wear and is likely to be more reliable in showing a bend on an un-re-ground crank.

[gaspen]

 

I guess it isn't good news https://photos.app.g...PxoubKvgayWCZh8

 

OK, that looks to be 0.14 mm or 0.0055" to me !

 

Has it been re-ground ?  If not, this may just be the wear in the mains, they don't wear round, so maybe pop the crank out and check the diameters of the journals in at least 3 places around the diameter. If it's been re-ground (and from memory, it's not), then it has a bend.

 

While you are set up this way, place your DTI on the Crank Nose and check here too. That's not normally subject to wear and is likely to be more reliable in showing a bend on an un-re-ground crank.

 

 

The crank was not re-grounded. I measured the mains in many places, everywhere it shows 44.47 mm.

 

The "original" shells do not show bad wearing, see picture. Also the contact surfaces on the caps are clean, I mean there is no pitting as on the block side.

 

I also measured the middle journal  with DTI while the crank turned on the 1st and 3rd bearing shells. It shows 0,04 mm ( .0016" ) run-out. 

 

I will measure the tail this afternoon

 

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[mini13]

just a thought,

Ive had engines where they pinch up due to the main bearing alignment dowels being a loose fit.... i always use the billet ones now

[gaspen]

just a thought,

Ive had engines where they pinch up due to the main bearing alignment dowels being a loose fit.... i always use the billet ones now

 

Which is the "billet" one ?

[mini13]

Ive used both of these over the years.

 

https://www.swiftune...p-dowels-2.html

https://kentautodeve...-cap-dowel-sets

 

[Spider]

Ive used both of these over the years.

 

https://www.swiftune...p-dowels-2.html

https://kentautodeve...-cap-dowel-sets

 

These are both good but just be aware those for a 1275 are a different size to the small bore engines. Not sure Swifties do them, but I see KAD do.

[gaspen]

 

I guess it isn't good news https://photos.app.g...PxoubKvgayWCZh8

 

OK, that looks to be 0.14 mm or 0.0055" to me !

 

Has it been re-ground ?  If not, this may just be the wear in the mains, they don't wear round, so maybe pop the crank out and check the diameters of the journals in at least 3 places around the diameter. If it's been re-ground (and from memory, it's not), then it has a bend.

 

While you are set up this way, place your DTI on the Crank Nose and check here too. That's not normally subject to wear and is likely to be more reliable in showing a bend on an un-re-ground crank.

 

 

When you say "Crank nose" you mean the clutch side where the primary gear runs ? I guess I should measure not where the bushes run, sure ?

[Spider]

When you say "Crank nose" you mean the clutch side where the primary gear runs ? I guess I should measure not where the bushes run, sure ?

 

Either end will work for this check, though the Crank Tail (Flywheel end) is better as it's longer. The 'nose' is like your nose - on your front side (or that's where I hope it is !) so, it's on the front of the engine (water pump end).

[gaspen]

 

When you say "Crank nose" you mean the clutch side where the primary gear runs ? I guess I should measure not where the bushes run, sure ?

 

Either end will work for this check, though the Crank Tail (Flywheel end) is better as it's longer. The 'nose' is like your nose - on your front side (or that's where I hope it is !) so, it's on the front of the engine (water pump end).

 

 

Okay, that's fine

 

And I will also measure the journals which runs on bearings just to be sure

 

See you later 

[gaspen]

Here we go :

 

The crank is supported on the 1st and 3rd bearing shell. At the 1st and 3rd journals I can measure 0.00 run-out. I believe it proofs that they are round.

 

At the middle main journal (without shell) I can measure 0.05 mm ( .0019" ) run-out.

 

At the tail (beetween the primary gear bushe's marks, where the is no wear) I can measure 0.03 ( .0012" ) mm run-out

 

Also I marked both high points : they are 180-deegrees to each other.

[Spider]

Yes, does sound bent to me !

 

Correcting that shouldn't be too difficult.

 

Good work finding it.

[gaspen]

Yes, does sound bent to me !

 

Correcting that shouldn't be too difficult.

 

Good work finding it.

 

Thanks 

[gaspen]

Finally I took the block to the machine shop. They straightened, re-grinded and polished the crank,  but they did not resurface the bottom. They said it would be too much, so the just line-bored the mains. I measured it home and it seems fine for the main's specifications.

 

King Engine Bearings (MB 311AM +010) Main Bearings

 

 

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