lost a rod bearing

cool40 wrote:piston hit the head   i had the same deal last year.

BOSS 429 wrote:how much oil did you have in this engine, sounds like it ran low filling up the valve cover area.

when you were priming it what did it look like in under the valve cover?

also how long did you prime it for?

rmcomprandy wrote:Getting correct oil clearance is not the only thing to be checked upon pre-assembly.

1. are all the rod big end bores STRAIGHT and ROUND?
2. do the crankshaft journals exhibit perfectly ROUND and very little tapper journals of the CORRECT SIZE with good surface finish?   (You can't see minor chatter with the naked eye)
3. Are the main bores in the block STRAIGHT and ROUND"
4. are the bores perpendicular to the crankshaft centerline?

Wheelie58 wrote:Is there evidence of "radius ride"?
If the journals fillet was touching the bearing, it will definitely cause early failure.
Easy to overlook.
Keith

c.evans wrote:Dennis,  

Well of the two different cranks you have pictured, I'd much rather be using the one with the gray colored cheeks and counterweights, than the one with the black colored cheeks and counterweights.  The gray colored one has a much bigger and nicer fillet radius than the black colored one, and I believe will prove to be the stronger crank.

I do think you have an oiling problem, that is related to the clocking and location of those oil holes in the black crank.

Another thing I noticed on the black crank is, that on it's main journals, I see that they chamfered BOTH the leading and trailing edge of the main oil hole.  IMO that's wrong on the mains and allows the main to bleed off oil pressure.  Only the leading edge of the main oil hole should be chamfered, as this helps capture and maintain oil pressure going to the rod bearings.  I could not see the main bearing oiling hole on the gray crank, however if we could see and study it, I suspect it only has the leading edge chamfered.

Did the rod bearing that went south occur on cylinder numbers 3, 4, or 7?

Charlie

supervel45 wrote:No expert, but I do not like the black crank. It looks like it would only oil one side of the rod bearings, the way the holes are spaced. You did not mention how much side clearance you where running on the rods, but if it is on the loose side, it would seem like you would loose alot of pressure between the center of them, and not oil evenly across the bearing?

Lem Evans wrote:Were the 360 cnc heads the 85cc chambers? If so, they take a bastard dome. I do not use them.

powerstrokeace wrote:I know for a fact that the OHIO cranks are fat and out of round and need to be machined before any thing else. these are not plug and play. I happen to have one that my crank grinder said finish the rods and the align hone first. Install the bearing and give him the measurements. from that he finished the crank and its spot on. As for the piston hitting the heads i have a whole nother comment i'll keep to myself. But since you lost the bearing it had extra play so it would hit the head. So the delema is what was the real failure? did the piston hit befor the rod failed or after Ace

powerstrokeace wrote:I know for a fact that the OHIO cranks are fat and out of round and need to be machined before any thing else. these are not plug and play. I happen to have one that my crank grinder said finish the rods and the align hone first. Install the bearing and give him the measurements. from that he finished the crank and its spot on. As for the piston hitting the heads i have a whole nother comment i'll keep to myself. But since you lost the bearing it had extra play so it would hit the head. So the delema is what was the real failure? did the piston hit befor the rod failed or after It should not be too hard to install a new bearing on the suspect rod/piston, and mock the engine back up and check clearance on the head. Did your Ohio crank have the oil holes drilled like this one does? Randy also mentioned checking the rod big end for roundness, and that needs to be done now since the bearing spun on it anyway. Hope you get to the bottom of it.








Ace