Rod cap mix-up

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blasphemous

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Well, my memory failed me while I had my motor disassembled. I kept the rod caps in order, had them marked 1-8. However, what I did forget was which way they were orientated on the rods. It's a 1978 440 out of a motorhome if that makes any difference.
Does it make a difference if they're flipped 180 degrees? There's a channel of some sort only on one side of the caps.
 
Look at the side of the rod. You will see a chamfer that is there to provide clearance for any radius the crank may have. The locking tabs will be next to one another and facing the outside of the engine when you have that cap and rod chamfer matched up. This is the way the rod must be hung on the piston.
 
Great, thanks guys. I'd rather ask (and I tried to search first) and appear silly than let my pride hurt my wallet.
 
It is usually easier to answer a "stupid" question than fix a stupid mistake!!!

BTW...NOT a stupid question!
 
As said above the tabs on the caps are on the same side. The oiling holes point towards the opposite bank of cylinders.
 
Ok, a continuing problem since I got the rod caps installed.

With just the main caps torqued down, the crank still spun fairly easy. The first set of rod caps on and torqued I didn't notice a difference. After the second it got a little tighter, but not much. However, after the third set... I couldn't turn the crank at all. All I did was pull the caps to inspect the bearings and they were re-installed in the same order (and direction thanks to FABO). What gives?
 
Are you plasti-gauging the rod clearances as you install them ? Maybe the bearings are too tight ? Also assume you are putting some motor oil or assembly lube on the journals ? Can you slide the rods back and forth a little on the crank journal ?
 
Look at teh bearing. There will be shiney spots where it contacted the crank. You need to see where it hits, and figure out why. What in terms of machine work and new parts were put in the lower end? Be specific.
 
Maybe this will help. Look at the pic and notice that the bearing "notches" are installed on the same side of the rod. The notches allow the bearings to interlock to prevent spinning on the crank. Remember this - if the engine turned freely BEFORE disassembly - then you probably did something wrong on re-assembly. Check the rod cap alignment and also the piston alignment in the cylinder. The "arrow" on top of the piston has to point to the front of the engine.

Turn the engine over after installing EACH piston/rod assembly. If it gets tight or locks up - STOP and inspect. Do not proceed until you get it turning freely again. NEVER use a breaker bar or cheater pipe to help turn a tight engine. This will really get you in trouble. I hope this helps you with your problem. Good luck, David

I-Beam.jpg
 
The rod caps are installed correctly per the picture.

No machine work was done. I bought this motor "used", but I opened it up just to check the journals and bearings. It turned over by hand before disassembly.

I'll follow that advice, I'll remove all the caps and start over. Turn it over each time I install a cap. When I get to the one that is giving me trouble, I'll go from there.

Thanks again guys, back to the wrenches!
:read2:
 
If it turned before, then you want to make sure it's all back right... and that you are not over torquing the rod bolts.
 
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