Rod side cl

[speedduck]

 How important is the connecting rod big end side clearance ?
I have Marine crank and Falicon rods, side clearance is .03" , i think its a lot 

[knecum]

.03 meaning  .030 thou??  yes that's  to much and its very important, the clearance allows oil to escape and the incoming oil cools as it flows through.  I like .006-.009, Min .006.   service limit in the book is  .012 I think. To little overheats the oil and a spun bearing could be the result, I find it all the time with a certain brand rod. W, I have to get every set machined when a customer supplies them.

[speedduck]

Yes, i mean 0.75mm. What can i do when it`s loose, not tight ?

[knecum]

Yes, i mean 0.75mm. What can i do when it`s loose, not tight ?

  measure the rod and compare it to the spec card, either the rod is wrong or the radius on the crank is to thin, is it a weld up? is it on all 4 pins?

[speedduck]

All 4 are the same, rods are Falicon Knife`s and crank is Marine billet. Std rods are 21mm wide at the big end and these are 20.7mm, so the rest comes from the crank. I think it will be ok,

[LVBUSA]

Please correct me if I'm wrong.

Wouldn't excessive side clearance cause a certain amount of oil pressure drop overall ? If the gap keeps a pressure threshold stable, then too little would restrict and overheat the bearing / journal surface. Would it then be reasonable to say that excessive gap would allow too much flow affecting oiling in the rest of the region ?. Being clear that the oiling / bearing gap is in spec of course. If you're running at .029-.030, then you're running five times what is the recommended range.  Wouldn't that make for a lot of oil passage if, let's say, all four side gaps were at this given gap ?.

Or is the pump putting out sufficient pressure to compensate ?

Just curious.

Thanks Duck for the topic.  Getting ready to start my build and stuff like this is making me a sharper builder.

A.

[Ghost-Geezer]

https://www.youtube.com/watch?v=Q3Qm7vRoPKo - Rod bearing to crank

https://www.youtube.com/watch?v=HsqL7bho2No - Rod side clearance

30 thousandths is not even in the ball park for a side clearance..........and these are car engines. 

Does not compute.  Rods walkin' all over the place, piston rockin' side to side, rings also.......does not sound healthy to me.

[Jay]

Your rods are .012 narrower than a Carrillo, which fall right in tolerance for us. Interesting to see where .030" comes from.

[speedduck]

I measured the gap with feeler gauge just like in the video.
I can pump up the oil feed if it lowers the pressure, but don`t think so when bearing clearance is in order. It may rattle, or not. I don`t have much choices here, do i. Someone would remove these rods and install another ones, but i have to make this work with what i have now, sometimes it goes like this.

[LVBUSA]

I measured the gap with feeler gauge just like in the video.
I can pump up the oil feed if it lowers the pressure, but don`t think so when bearing clearance is in order. It may rattle, or not. I don`t have much choices here, do i. Someone would remove these rods and install another ones, but i have to make this work with what i have now, sometimes it goes like this.

Forgive me Duck for asking,

          Why are you putting this motor together with the current gap setup ?.  If you know you have an out of range measurement that is.  If the rods are pretty close to spec then the crank is suspect.  If the crank is within or close, then the rods are suspect.  Might be a little of both.     

What's the rush on the build  ?.   

A.

[Ghost-Geezer]

With 30 thousandths, the rod side to side movement on the crank will force the sides of the piston to keep things in line, that could easily place undo stress on the piston, rings and wrist pin, as well as the cylinder walls, not to mention the upper rod bushing.  It just does not smell right to this old nose.

 

[LVBUSA]

With 30 thousandths, the rod side to side movement on the crank will force the sides of the piston to keep things in line, that could easily place undo stress on the piston, rings and wrist pin, as well as the cylinder walls, not to mention the upper rod bushing.  It just does not smell right to this old nose.

 

From what you made reference to earlier, I wondered about the same.  You have .030 worth of gap.  You have a rod riding in a wide space even if the bearing/pin gap is perfect.  You have a piston pin that will allow it.  The piston's going to be working awful hard at keeping lateral forces under control until the rod bushing starts to wear along with the piston, rings, and cylinder wall.  Now you have 4 cylinders with the same scenario.  Even at idle it's going to be a sloppy situation, not to mention at rpm.  So it just has me wondering what's making Duck want to push on and build irregardless ?.  Just curious is all....... 

[speedduck]

I measured the gap with feeler gauge just like in the video.
I can pump up the oil feed if it lowers the pressure, but don`t think so when bearing clearance is in order. It may rattle, or not. I don`t have much choices here, do i. Someone would remove these rods and install another ones, but i have to make this work with what i have now, sometimes it goes like this.

Forgive me Duck for asking,

          Why are you putting this motor together with the current gap setup ?.  If you know you have an out of range measurement that is.  If the rods are pretty close to spec then the crank is suspect.  If the crank is within or close, then the rods are suspect.  Might be a little of both.     

What's the rush on the build  ?.   

A.

Justified question. I`m angry at myself not noticing this before when i had lots of time to figure out different solutions. I just thought it will be ok when parts are newish, crank`s been in a motor but not running, rods been on my shelf for long time, one of them is new, others like new.
There is more clearance in piston, the rod will not lean into piston.
Question here is, does this really cause problems or is the side clearance tolerance less significant.

I can try it like this and tell you how it went, but, i`ve just broken gearbox three times on my turbo, it feels that i`ve had enough technical trouble for this year.

[Ghost-Geezer]

I called Crower today and discussed side play between rods and crank journals.  The main answer I got was that it is better to not have the clearances too tight compared with factory specs.  I was told it is better to have them too loose than too tight.

That is what I was told............as far as .030 is concerned on a Busa motor, I was told that is up to the builder. 

[knecum]

I would send the crank back if it's convenient to have them double check their work. But before that I would put on a Carrillo h-beam rod and check the side clearance with that I can send you one if you want if you have to use those cheaper rods I would run 15/40 or 15/40  motul with a relief valve

[speedduck]

 I really appreciate the advice and opinions. Now i have lost the deadline to finish this motor for next event i may as well go through it trying other parts and check clearances.
Thanks Steve for the offer, i think it`s much easier to find other rods nearby here, there is friends motor coming for a check and i could try out his rods.

[speedduck]

Btw , i been using 15w50 oil

[Ghost-Geezer]

Motul or Rotella or Alisyn or Amsoil?

[speedduck]

It`s a brand not available in US, i think.
http://www.motonet.fi/fi/tuote/592022/MP-Teboil-4T-SuperBike-15W50-4L


This is what i`m about to try next,

http://www.xenum.com/product/wrx-7q5w40/

[LVBUSA]

Duck,

       Real sorry you missed your deadline, but it may have cost you more in the long run.  Great topic and insights for a discussion nonetheless.

Thanks and good luck !!!

A.

[GSXRTURBO1]

This is what i`m about to try next,

http://www.xenum.com/product/wrx-7q5w40/

Hmmmmm 

What's next, super-micro ball bearings in oil suspension? 

I do like the synthetic ester base, but micro-ceramic particles? Sounds like it could be snake oil. Would love to see some Don "Rotts" type testing

[speedduck]

Yes, gotta try something every now and then, oil is easy and harmless to try out.

I got a standard rod and tried it on, there is the same clearance, so it`s the crank. I dug out the box it came in and found out some writing on it, it may solve this issue, i just need a little help figuring it out.
It says 38mm diameter, 21.50 thick , then came to mind that there is one option that uses ZX14 bearings, can this be it ?

[LVBUSA]

 

Okay, who has a ZX14 shop repair manual ???........what's the crank journal spec ???....

So the rods you measured are both similar ???...

Cool find by the way !!!

A.

[speedduck]

Busa rod bearing is 17mm wide, i asked my friend who has done kawasakis and he measured ZX14 bearing 18.9mm.
I sent an email to Marine about this issue and they asked for serial number on the crank, i found only the 603-B and something that was not clear enough to read.

[Jay]

I thought at first you may have had a crank that was done for ZX14 big end. Looked in the Carrillo book for big end widths and the 14 is much wider than what you are stating you have as side clearance.

Are you sure it is a Marine crank?