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how to tell if you conrods are bent
https://www.ausmini.com/forums/viewtopic.php?f=2&t=29343		 Page 1 of 1
Author:  volkmini [ Sun Mar 18, 2007 7:48 pm ]
Post subject:  how to tell if you conrods are bent
i was reading an engine build buy GR and he said that most people don't check if the conrods are bent. but i'm woundering how do you check if they are bent.
thanks
Author:  drmini in aust [ Sun Mar 18, 2007 7:55 pm ]
Post subject: 
You can get an idea if bent, just by looking at wear marks on the piston skirts, which should be even each side.
But... ideally you need an alignment jig, which Graham has. It puts 2 parallel bars through each end of the rod, and a dial gauge then checks them for parallelism.

<edit> when I checked the S rods going into my 1412 stroker motor, all 4 were bent a bit, so it's worth checking. :wink:
Author:  Lillee [ Sun Mar 18, 2007 9:44 pm ]
Post subject: 
Aaron and I checked 16 998 rods and all were bent. 4 were less bent that the other 12 :wink:
Author:  drmini in aust [ Sun Mar 18, 2007 9:48 pm ]
Post subject: 
Lillee wrote:
Aaron and I checked 16 998 rods and all were bent. 4 were less bent that the other 12 :wink:

Ah, you can't beat the A series' agricultural engineering. 8)
They still run, regardless- have done since the A30's 803cc of 1951... :lol:
Author:  rampage101 [ Sun Mar 18, 2007 10:12 pm ]
Post subject: 
Specialist-Components in the uk are making some very nice billet A+ rods, @ £665 a set. :shock:
Author:  sgc [ Sun Mar 18, 2007 10:15 pm ]
Post subject: 
I bet Doc could make them cheaper :wink: :wink:
Author:  Mike_Byron [ Sun Mar 18, 2007 11:08 pm ]
Post subject: 
The process of checking and restoring bent and twisted conrods is called resizing. it should really done be part of enginering in any engine reco but alas it carries a cost.

The figures are staggering for the number of used conrods that are not stretched, straight and true.
Author:  Wombat [ Mon Mar 19, 2007 9:04 am ]
Post subject: 
I had my conrods checked and straightened - cost about $150 - I say about as I had been quoted around $200 for other work I was having done and threw in the conrods without asking the price and the total bill was $356
Author:  9YaTaH [ Mon Mar 19, 2007 9:19 am ]
Post subject:  Modulus of Elasticity
Excuse a dumb question....but what is to stop a straightened conrod (and I assume therefore slightly weakened) from assuming the original shape once slapped (hmmm poor choice of words :?) back into an even higher compression engine.

I spose its all about stress relief :D
Author:  Lillee [ Mon Mar 19, 2007 11:45 am ]
Post subject: 
Nothing. One of a few things apparently will get them back into bent shapr: stress relief via heat, or a big bang. They are tough things so they don't easily bend and stay bent (it takes a vise and special teeth to bend them even just a fraction).

Also we are talking sideways bend, that is along the spines of the conrod where they are strongest.

At least the idea is to start with a strauight rod, if it bend with time, straighten it again. Better than starting out with a bent rod! I've seen them mroe than 100 thou bent :shock:
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