Connecting rod length

[Zetomagneto]

Hi Colin, yes some ambiguity in the opening post but things usually become clear in further discussion.


Re grinding, an offset crank grinder is best, you set the throw and all pins will then have an equal throw.

I don’t particularly like the other type which follow the the worn pin and therefore don’t necessarily correct, or equalise the throw.

[Roger]

Hi Colin, yes some ambiguity in the opening post but things usually become clear in further discussion.


Re grinding, an offset crank grinder is best, you set the throw and all pins will then have an equal throw.

I don’t particularly like the other type which follow the the worn pin and therefore don’t necessarily correct, or equalise the throw.

Hi, 
I agree with your comments regarding the offset grinder and understand that the crankshaft should not be ground incorrectly as these machines are designed to do it right.
And by the same token machining the rods is done in a jig, as has been shown on forum posts.
So how can they not be correct if done by a competent machinist?
Although they look good I am now worried about the quality of the workmanship, but as I have had the parts for a long time it is too late to return them I guess.

Roger

[Howard Wright]

Hi Roger

Is it possible that the rods have been machined this way “on purpose”?

As many have suggested crank whip on a 2 bearing engine necessitates no 2 and 3 to have a slightly lower piston height.

It would be an innovative answer if this is the case!

Cheers

Howard

[Roger]

Howard,
Unless the person requesting the regrind was a knowledgeable Austin Seven owner it would be unlikely that this would be done deliberately, unless of course if the person doing the job knew what it was for and was experienced in that area.
It would have been good if this information was then relayed to the customer and noted for future users.

Roger

[squeak]

Or just number the rods. Paint dots?

[Ian Dunford]

There are so many ifs and buts in this posting that if it was me I’d be inclined to start again from a situation in which I knew the whole history of all the parts I was going to use.
Starting with crack detecting and then going on from there.

[Roger]

Ian,
Thank you for your comments, unfortunately this is a rather slow project as I have too many other distractions at the moment. As I mentioned previously I bought this from and unknown person on eBay, in retrospect not  a good move so do not know it’s history.
I am satisfied the crank is ok, and the rods in the correct location now. I will continue with the rebuild but will not know the results until early next year. 
I will post an update then.

Roger

[Ian Dunford]

I’m not familiar with the workings of eBay myself but is there any valid reason why you can’t ask for your money back from the third party considering the problems you have problems you have discovered with this product?

[Roger]

Ian,
I am in discussion with the seller who assured me the work was done by a long established firm, he lives near street I understand.
The discrepancy in length brings doubt about the quality of their work.
The thickness of white metal is my main concern (more at the top, less on the cap), the rod length cannot change.
I await the reply, I wonder if he is a forum user?

Roger