connecting rod Question

Dennis Pereira

Dennis Pereira

Well-known member
I'm Cleaning up a engine That I was told had been refurbished? I Drained the oil / Heavy crude I pulled one cap and the babbitt it looks great but I had to rock the cap to remove is there a stone or method to deburr or is this a machine shop job this is going to be a pain if there all like this. No shims unless there stuck to the rod side.
 
not sure what your getting at but if i understand you correctly, oftentimes the rod bolts dont align perfectly with the holes in caps.gentle persuasion is needed to assemble/disassemble. but i wouldnt try to alter anything as it may affect alignment of cap to rod causing poor fit to the crankpin
 
That's what I was trying to ask. If I could clean up the holes in the cap. Seems like there's burrs the cap was real hard to remove. I had to rock back an forth and a little gentle prying to remove seems like this will be a problem to plastigage. This is new to me so I'm going slow. I'm good at parts replacement but not a machinist
 
Dennis...Don't mess with the holes, it's for alignment, all they need is a little tap. Now the big question, do they have shims, you weren't sure?


Dudley
 
Dennis Pereira said:
That's what I was trying to ask. If I could clean up the holes in the cap. Seems like there's burrs the cap was real hard to remove. I had to rock back an forth and a little gentle prying to remove seems like this will be a problem to plastigage. This is new to me so I'm going slow. I'm good at parts replacement but not a machinist
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As the others have said leave it alone. As for plastiguage I use the aluminum foil method.
 
d.j. moordigian said:
Dennis...Don't mess with the holes, it's for alignment, all they need is a little tap. Now the big question, do they have shims, you weren't sure?


Dudley
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No shims Heres a photo of one of the caps. There seems to be a lot of babbit left. The engine looks to be rebuilt stainless valves ? 6050 speed head with a casting date of 5-27-31 engine numbers filed off . Oil looks like it was never changed.
 

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I'm thinking of cleaning every thing up and new gaskets and rings and lap the valves I cant feel any play up or down looks like new pistons. Ill know more when I pull the head its still hanging from The hoist. This was a free engine so I wont be out anything. I was cleaning it up for a possible core.
 
Mike V. Florida said:
As the others have said leave it alone. As for plastiguage I use the aluminum foil method.
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I would disagree with the others. If you know a machinist or have access to a shop borrow a single flute 45 degree counter bore and have them or do it yourself in a drill press. You would want the spindle turning at its slowest speed. This is a very simple operation. The tool only cuts the burr at the edge of the hole unless you hold the part up to cutter with too much pressure. You only cut it enough to remove the burr. This is called chamfering. I specified single flute as multi flute cutters tend to chatter more. I'm assuming that you were not concerned with the hole itself just the burr or displaced metal at the edge of the hole raised by the tightening of the nut which causes caps to hang up.
 
thanks for the tip Its just the edge of the bolt holes. It looks to me they over tightened the caps and with no shims there's a little burr on a couple of the caps. apparently they filed to fit and there hanging up on the connecting rod bolts. This might be a job for a pro I can see where I could screw this up.
 
I never saw them any other way. The caps are always a bit of a frig to get off, but but short of dowl pins, thats the way it was done. Leave it alone. If there were no shims between the rod and the cap you aint gona do much with it. Should have shims, or theres no adjustment left. Iceman
 
Some points,
I am a machinist (Tool and Diemaker) and as someone said, you could take a 45 deg. countersink and just dress the hole up by countersinking the hole and giving it a mere .010 to .015 chamfer. This means running the drill press as slow as it goes, Barely turning! You'll know when it's .010 when you have a shiny, no bigger than a pencil line, chamfer on what used to be the sharp corner of the hole, Next I would take a welding rod, bend the tip around, put a short pieces of sand, emery, garnett paper, whatever, in the bend and put the other end in the chuck and "Lap" out the hole a little. Not much! This will make all the high spots (Thread marks and gouges) more visible with out removing any material from the hole. Now you should be able to see exactly what the condition of the hole is and work from there. Clean VERY well before reassembly.

Aluminum foil for plastigage? Sounds dangerous to me! I don't want anything but oil between the rod bearing and the crank journal. Plastigauge is cheap and available! Why fool around with something else?

If as Iceman said, there are no shims, then he is right, there's no adjustment left!
You had better check with plastigauge. with your discriptions of how well the engine seemed to have been maintained, it's entirely possible that the clearances are out of spec now. Good Luck !
Terry
 
I've seen rod bolts splayed outward causing problems with removal and installation too. They can be straightened by squeezing in a vice or tapping with a hammer gently. Straight bolts is but one of the things I look for when choosing rods to use.
 
Controversial, but, you can have the caps surfaced about .012" then put 4 .003" shims in. As long as there is enough babbit, it'll outlast you.
Whatch think?
 
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