Fuel's Winter Project: Build It Before It Blows

[BruceH]

Josh, when you get the crank out run pipe cleaners through the oil passages and the oil galleries in the block if you can. I wouldn't be surprised if there were burrs or other obstructions in some of the oil passages.

The whole thing is just too inconsistent for an easy answer imo. I'd think that your machinist bored each cylinder to a piston and numbered them. If so then you already know he took the time to measure everything. IIRC those pistons are Manley 2618 made for mmr without a real skirt coating, just the mmr whatever it is that wears off. That would put the ptb at .003-.0035 depending. For your use .0035". If they were skirt coated then the clearance goes down but it depends on the coating.

Anyhow what I'm getting at is that it just doesn't make sense for two pistons on opposite ends of the block to suffer this fate but all the other pistons to come out fine and no crank or rod damage.

I'm really surprised you even have the mindset to tear it down after something like that happening. I'm not sure where my head would be at.

 

[JoshK]

I am not sure if I should be puzzled or not? I do know this thread is making me more uneasy about the whole thing. The pistons were not numbered when I got them from the machine shop. He did measure each and every piston on the previous engine though. I will find out the ptb clearance when I take the engine back.

I will try the pipe cleaner method Bruce, hadn't thought about that.

 

[loots06]

I hate see stuff like this especially considering I'm going through a build at the moment. Sorry this happened to you. I'm going to go back and check on the ptb clearances on my short block.

 

[JoshK]

Main bearings and crank













Thrust washers

 

[BruceH]

From here it all looks normal. How were the oil passages? I'm going to guess they are clean.

Did your crank require beveled bearings for the radius clearance on the rod journals? What I'm wondering is if it did and the bevels were installed 180 degrees out on the affected cylinders it would impact the oil slinging that's used to lube the cylinder walls. It's just another random thought.

 

[JoshK]

I know it is sad to say, but I am not following you there Bruce. I had the machinist order the rod bearings for me. The crank was used so I wanted him to check it before the bearings were ordered. All bearings were installed exactly the same though.

 

[BruceH]

I know it is sad to say, but I am not following you there Bruce. I had the machinist order the rod bearings for me. The crank was used so I wanted him to check it before the bearings were ordered. All bearings were installed exactly the same though.

The Kellogg stroker crank in my motor uses small block chevy rod bearings. The sbc bearings have a beveled edge and a straight edge. The beveled edge goes toward the outside. The reason for this is to clear the machined radius that exists on chevy cranks. IIRC (it's been awhile) the Kellogg crank doesn't have the radius just like the stock crank doesn't. Stock rod bearings are beveled on both edges I think. I don't have a set to look at but I do know that orientation of stock bearings on a stock crank doesn't matter. I also know that the Eagle crank does have the radius.

This is just thinking out loud for discussion purposes. If the sbc bearings used for the rods had the bevel orientated toward the center of the journal instead of the outside could it be possible that it would reduce the amount of oil that is slung out for piston lubrication? I don't have the answer to that question. If it did reduce it some but not all it would be plausible that the piston skirt would take awhile to start showing the effects but once it started to wear down it the cumulative effect would accelerate wear.

Are my thoughts coming out clear or is it just a bunch of jumbled up words?

 

[BruceH]

Here's a pic of the sbc bearing that has to be used with a 2" rod pin on a stroker crank. See the bevel?

 

[JoshK]

That makes sense to me

 

[JoshK]

Here's a pic of the sbc bearing that has to be used with a 2" rod pin on a stroker crank. See the bevel?

Oh okay, well it is very hard to tell now that the bearings are used, but it does look as though they have that. It doesn't seem to be that much though?

Here is the part # of the rod bearings I have. cb745hn

 

[BruceH]

Oh okay, well it is very hard to tell now that the bearings are used, but it does look as though they have that. It doesn't seem to be that much though?

Here is the part # of the rod bearings I have. cb745hn

It's enough to make a difference. Here's a bad pic of stock style rod bearings that have the bevel on both sides. It's hard to see the reliefs.

If your crank had the rod pin radius then it would of really made a difference because the bearing would of been in the radius. IIRC Eagle is the only one with a big radius.

FWIW this was the teardown pic from my first motor build. IIRC there was about 15k on it. The shooting star marks are perfectly normal and they are a sign that the bearing was working as intended. The marks are caused by particles getting trapped in the bearing. That is the design of that particular bearing.

 

[JoshK]

So the knocked off corner on the right side of the bearing(in this pic) marks the beveled side, that correct?

 

[BruceH]

So the knocked off corner on the right side of the bearing(in this pic) marks the beveled side, that correct?

I don't know. The bevel is fairly evident though, it doesn't need a marker.

I can't remember what crank you have. Is it a Kellogg with 3.8" stroke?

 

[JoshK]

These two pictures are of opposite ends of the same rod journal on my crank. Is this what you are referring to as the radias?

 

[BruceH]

These two pictures are of opposite ends of the same rod journal on my crank. Is this what you are referring to as the radias?

Yes. Here's a pic from my crank 3.750" Kellogg) of the same thing. The outside of the pins have the radius that's left over from the machining process. It's also part of the structure that prevents stress risers from forming. A squared edge would essentially be a trap for harmonics and other stresses.

 

[JoshK]

Okay, so it would be necessary for mine to have the single side bevel or at least must have the bevel to the outside to help with splash lubrication? I am starring to get a little confused now

 

[BruceH]

Okay, so it would be necessary for mine to have the single side bevel or at least must have the bevel to the outside to help with splash lubrication? I am starring to get a little confused now

It probably is. Without a test lab and funding we will never know how important it is. What I do know is that the bevel is designed as a relief for the radius so it's a good idea to install the bearings that way.

 

[JoshK]

This is what I was talking about Bruce. You can see the bevel on the right but not the left







This is with the two notched sides lined up like this, but that makes the locator notches for the bearings on opposite sides(which is not how I had them installed)



This is the other side of the bearing that seems to not have a bevel at all

 

[JoshK]

Not sure how much the tapered bevel holds true looking at the other bearings, but I am pretty sure I had the rod caps 180° off.

 

[swflastang05]

IIRC my rods have a bevel built into them (Manley H-beams, and I have a Kellogg 3.750 stroker crank) the bearings do not sit in the center they actually sit off to one side more than the other and of the course the side with the larger clearance faces the crank counter weight and the other side faces the other rod.