is one of my rods bent?

jetpilot36

jetpilot36

Location
Fort Worth
I went to split my cases today and I turned my engine upside down to take the bedplates off. I didn't realize the weight of the engine was resting on the connecting rods. I think I bent the rear rod. if so, where is a good place to get the rod replaced?

the first pic is of the straight rod.
second pic is the rear rod. can you guys tell a difference or am I seeing things?straight rod.jpg bent rod1.jpg
 
OCD Solutions

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
I have 4 rods here I cut off various cranks that I can experiment with if you really need to know what it takes but...you were tearing the engine down for a reason, I think you just found your reason.
 
jetpilot36

jetpilot36

Location
Fort Worth
That's the only thing i could think of, because it was rotating fine in the cylinder. No unusual scoring.ill post pic of the cylinder tomorrow. Seems like if it was bent before I disassembled it, it would show signs of unusual wear. That's the only way I can explain it getting bent, unless it was bent before I took it apart. If that's the case, then I can assure you it did not give me any problems at all
 
OCD Solutions

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
I just stuck one rod end in a vise, slipped a 16" piece of 1' pipe thru the wristpin end and hung off it. (205 lbs). It sprung back to it's original position.

I bounced on it a few times and was able to deflect it a few degrees over the length of the rod. It was not nearly as abrubt as your bend though. By my quick little test, I would say you were torquing on a bolt and put additional pressure on it at some point.
 
jetpilot36

jetpilot36

Location
Fort Worth
OCD Solutions said:
I have 4 rods here I cut off various cranks that I can experiment with if you really need to know what it takes but...you were tearing the engine down for a reason, I think you just found your reason.
Click to expand...
I originally took the engine out because of a faulty MSD TL. Engine was revving out of water, but under a load it wouldn't rev and sometime would backfire. but get it on the trailer and the engine would rev fine like it normally does. so I took the engine out and bought a digital MSD TL. well while the engine was out, I decided to do a little case porting and just see exactly what my cases looked like anyway. that's why I tore it apart this evening. do you think the bent rod could have been the problem the whole time? (BTW the MSD TL that I had in there before bench tests fine)
 
jetpilot36

jetpilot36

Location
Fort Worth
OCD Solutions said:
I just stuck one rod end in a vise, slipped a 16" piece of 1' pipe thru the wristpin end and hung off it. (205 lbs). It sprung back to it's original position.

I bounced on it a few times and was able to deflect it a few degrees over the length of the rod. It was not nearly as abrubt as your bend though. By my quick little test, I would say you were torquing on a bolt and put additional pressure on it at some point.
Click to expand...
WOW that's a lot of force. so a few questions arise here
1. is there any chance the engine would run properly with a rod like this?
if not, then surely I must have bent it some how.
2. do you guys think a bent rod would cause the symptoms I described above?
3. where can I get it repaired? competitive cranks?
 
W

waxhead

wannabe backflipper
Location
gold coast
I wouldnt be using that rod again. It already been deflected twice and its likely to break or at least be alot weaker. normally in the situation you have you will have very strange bore wear . Look at the wear pattern
 
jetpilot36

jetpilot36

Location
Fort Worth
OCD Solutions said:
It would net lower compression in that cylinder and TDC would occur at a different time as well.
Click to expand...
hence the backfire from a different TDC. hence the lower
jetpilot36 said:
That's the only thing i could think of, because it was rotating fine in the cylinder. No unusual scoring.ill post pic of the cylinder tomorrow. Seems like if it was bent before I disassembled it, it would show signs of unusual wear. That's the only way I can explain it getting bent, unless it was bent before I took it apart. If that's the case, then I can assure you it did not give me any problems at all
Click to expand...
when I stated that it didn't give me any problems, that's because I thought it was the MSD TL malfunctioning, not a bent rod. if it really was the rod giving me problems this whole time, then I misdiagnosed it and I bought an extra MSD TL for nothing.
 
Harbor

Harbor

Location
Stockton
My guess is it's had some hydro locking at speed in the past..

Cocking the piston across the pin could effect ring sealing on both side of the piston
 
jetpilot36

jetpilot36

Location
Fort Worth
there's a possibility it could have bent when I was removing the wrist pin. I popped the circlip out and stuck a 12mm deep socket in on the other side. I used a rubber mallet and tapped the socket through the piston to drive the wrist pin out. but that's not very much force. ive done that a few times before with no problems on other 701's.
 
S

Schmidty721

someone turf my rails
Location
WI
OCD Solutions said:
It would net lower compression in that cylinder and TDC would occur at a different time as well.
Click to expand...

I'm not seeing how TDC would be effected by this?
Lower compression yes as the over all length from crank pin to wrist pin is slightly shorter, but this doesn't effect when TDC happens
 
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