Engine problems after 95" build part II - help needed

[Don D]

What could have caused this, was this crank from a motor that had some major failure?

[Ohio HD]

Adam, that last picture says it all if the angle you took it is true.

pix can bee deceptive but it's looking like a bent rod to me

put something in the rod to see if it's square to the case,

Yep, that's the money shot. You can see near the base of the rod a curve towards the sprocket shaft side of the motor.

[Ohio HD]

These guys got it, sure looks like the rear rod is bent. Below is how you check how bad it is. And also when straightening it, how far off, and how much more bend is needed.

This is an Evo motor, but it's checked the same way.

[kd]

I am thinking it would take a broken piston (maybe from something foreign going through the intake?) to cause that during running.  Maybe stretching it, even a right side collision. There would probably some other collateral damage marks if those were the case.  It's more likely that it was mishandled after disassembly from the donor engine.  Dropped on it's side or damaged in shipping is the most likely culprit.   

[turboprop]

Curious how that crank got into that case and installed in your chassis without the rods being checked for straightness. Seriously. The tool to check this is probably less than $50USD. I understand you are not a professional shop and and probably didnt install the crank yourself. Bottom line, the rods have to be checked and most likely twisted a bit. This is pretty common for harley engine builders but it will require tools that are only good for this operation and will probably require some training by a pro. Best of luck.

[speedzter]

As a quick check, use two piston pins to mimic the tool shown above , and check pin to block alignment.

[Adam76]

YEP, it's a bent rod. Just my luck 

I can source another crank and swap it all out again....

[Ohio HD]

If it were my bike, this is where I buy a 4.375" stroke crank, and a set of 103" pistons.

Go big, or go home. 

[Adam76]

I agree Ohio.
If I can't get hold of a decent crank for a decent price, I'll go stroker.

[rigidthumper]

I'd straighten the rod, but I'm also a cheap SOB.

[Don D]

Just straighten it and move on. Begs the questions, have the rod bearings been checked for no tight spots, has the crank runout been checked. Whatever it took to bend that rod could have done collateral damage.

[Ohio HD]

That's my reasoning for a new crank. Unless the crank is gone over 100%, it's still an unknown.

[Ohio HD]

I agree Ohio.
If I can't get hold of a decent crank for a decent price, I'll go stroker.

Keep in mind, it must be a stroker crank for your the earlier Twin Cam motor. The late model 103" crank is for a six speed drive line.

[Adam76]

Pulling the bottom end again, take 2...

My mechanic felt sorry for me, he had an early TC 88B crank that he was planning to sell, but he's giving it to me no charge. He has thoroughly checked it.  Rod are straight and runout is .0015

Praying it all goes together well this time.

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[wfolarry]

If you go to S&s's website they have instructions on how to make a rod straightening tool. Cheap & easy.

[FSG]

Cheap & easy

yes it is

[jsachs1]

Go into the "Home Made Tools" section on the forum, and you'll see the rod straighteners.
John

[FSG]

John your post of the tool has been there a looong time
and I have to admit that I've not seen it before or perhaps my memory is going   

what was the edit you did May of '21 ?

https://harleytechtalk.com/htt/index.php/topic,16681.0.html

[Adam76]

If you go to S&s's website they have instructions on how to make a rod straightening tool. Cheap & easy.

Thanks Larry and FSG.

I'm tempted to make the tool and just try and straighten the rod.

Here is another pic, is it too far gone to try and straighten it up?

I have another good and straight crankshaft lined up if this one can't be straightened.

Thanks

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[FSG]

I'm tempted to make the tool and just try and straighten the rod.

Here is another pic, is it too far gone to try and straighten it up?

well you've got nothing to lose ......  I'd straighten it

before you start I'd lightly mark/scribe a centerline on the rod end both fore and aft so as you go you have a good visual indicator between taking wrist pin measurements

[kd]

You also have a barrel and piston to use as a go / no go check.  If you don't want to put the ring set through a few check fitting exercises, take them off and test fit the piston with some masking tape on it.  Fit the piston to the barrel on the bench first so you know it's snug.

[Ohio HD]

You really need the connecting rod pin tool to know if it's straight again. As I posted the image a few posts back. And then you also need to make sure that rod isn't twisted, one of the two tools that John Sachs posted.


John Sachs Connecting Rod Tools

[Adam76]

Thanks guys,  but I'm not going to risk it. I have a good crank lined up to go in and the bottom end is already out of the frame.
Cheers

[jsachs1]

John your post of the tool has been there a looong time
and I have to admit that I've not seen it before or perhaps my memory is going   

what was the edit you did May of '21 ?

https://harleytechtalk.com/htt/index.php/topic,16681.0.html

Re edit:
Black Hills Ken sent me a pic of the rod straightener (straight tool) that he uses, to check the straightness, after tweeking. Wrist pin, with a straight mandrel pressed into it.

[FSG]

cheers