Connecting rod length

[Colin Reed]

HI Rodger,
As Tony has said not the rods,
I would suspect Crank has not been setup Properly for centre line for 1&4 , 
A lot just use a V block to centralise when setting on grinder so easy to get 20 thou out.
Cheers
Colin
NZ

[Bob Culver]

Hi Colin

Am unfamilair with crank grinder machines. Would be interested in a description of the setup please.
Based on many Javelin cranks, much work is dubious. The viatl radii usually destroyed and often the original oil seal track not even concentric!! Nitrided cranks often burned.

[Roger]

Good morning,
I have checked the piston crown, the result was they are all equal in height.
I then checked the con rod centres height,
The result was two rods are :- 5.575” and two are 5.560”.
This would explain all, I shall now use the two long ones on 1 & 4 so they are near the main bearings.
The two short ones will be 2 & 3 so they don’t hit the head if the crankshaft bends at higher revs.
I will use an appropriate shim to have the height of 1 & 4 equal to or slightly below the top face of the block.
Does this sound like a good plan?

Roger

[Tony Press]

You confused the issue when you originally reported-

"I have moved the position of the rods and get the same result so it looks as though it is the rod length."

[Robert Foreman]

I wouldn't be happy to use that crankshaft. I suggest that you contact the ebay seller and ask for a refund for incorrectly supplied goods.

[andrew34ruby]

Oh come on, it's only 15 thou adrift. Something sold on ebay, around 90 years old, and you would demand a refund for 15 thou??? Really?

[Robert Foreman]

Has the crankshaft been reground?  If so it has been done incorrectly.

[Zetomagneto]

Robert, just wonder why you think the crank is at fault. Roger opened with saying he thought there might be a difference in conrod centres, he has checked and now found that to be the case.
His intention to fit the 2 shorter rods to 2 and 3 seems to be a practical and sensible approach.

[Robert Foreman]

OK point taken. So agreed rods are at fault. Therefore if they were all bored at the same time there has been a serious issue with the boring.

[Colin Reed]

HI ZETO,
Unfortunately  ROGER gave the impression that he had change the position of the rods and still had the same result which I for one understood this to mean he had moved the centre two rods to the outside and still ended up with 20 thou protrusion on the pistons.
Now it would appear that the two out side rods were moved to the centre and still had 20 thou protrusion .
In this case a bit more clarity on the first post would have helped.
This is not a criticism of Rodger just something we all need to be aware of when trying to convey a problem that it can produce a misconception

Cheers 
Colin
NZ