Excessive movement caused by ???, the piston wrist pin in # 1 decided that moving to the edge of the piston and cylinder bore was a great idea, we now have two long stroke length vertical 3/4" apart deep grooves created by the outer two edges of the gudgeon/wrist pin... my question is without any noticeable removal of connecting rod bearing edge material, how does a pin move that far back and forth ?? could it be the rear bearing end play ??
Block is now in need of a re-sleeve and re metalling.
Pics will follow.
PREVENTATIVE MEASURES - would reducing the overall length of the pin by 1/16" stop this from ever happening again ?
David, for what it's worth, gudgeon pin scores are not the end of the world. I have pulled down a number of motors which were running well with a pin score. It is important to find the reason for the shift in the pin. Might the wrist pin bolt have been loose?
If the floating pin can be fixed, and the bottom end is fine, I would be inclined to run it and see what happens.
Others may disagree.
Allan from down under.
I had two cylinders with score marks... 2000km old engine.
The rods were twisted/bent slightly but enough to make the wrist pin slide out and score the cylinder wall.
I didn't have nay spare rods, much less any idea of how I was going to rebabbitt any...so I got the Snyders forged babbitted rods, and they are so perfect that the dynamic balancer guy said he didn't have to do anything to them... very impressive out the box surprise.
Hope this helps
I had that problem with two cylinders and after a lot of trying different things, we discovered the mains were no bored correctly causing the rods to force the wrist pins out the back of the piston, so i had a new Scat crank and had the mains rebored correctly and no more problem.
There were some of the Chinese made pins a few years back that were made to long, I got a set like that and ground the ends to the correct length and worked fine. I always check the length of all pins since that happened. KGB
The builder most likely installed bent rods and/or the crank mains weren't line bored correctly.
OK I got to asked.
How would the boring of the mains cause a wrist pin to contact a cylinder. Understanding that they can be bored off center causing timing gear clearance issues, it that would have nothing to do with shifting the crank forward or aft of center. Wrist pin is secured to pin by the bolt.
Besides the clearance between the third main of the block (not the main cap) and the crank when centered from what I have seen is around .012" to .020" or so depended on how hard the crank grinder hit the radius. Hardly enough play to cause contact even if all the Babbitt was lost on the third main cap.
Bent rod, it would really have to be bent.
Longer wrist pin, so far knock on wood I have seen that.
Losing the thrust off the rod will cause this problem but David states none that he see.
Loose wrist pin bolt maybe?
On tour a friend lost the #1 rod thrust around 10,000 miles on a rebuild, scored the cylinder deep, we put another rod in it and he drove another 10,000 to 15,000 miles before we rebuilt the engine. Didn't really burn oil, the only problem was the cylinder would oil foul out on a long down hill run. Most of the time it would clean up on its own, some times we needed to stop and clean it.
The oil misting from the valve cover was a bit of a sign that l did not pick up on early enough.
The grooves are deep, a sleeve is a must, the bore is now at 0.60", so maybe time for all 4 to be set back to 0.00"
No. 1. Check, not only wrist pin length, but length from the cut out for the wrist pin bolt to either end, one side may be longer.
No. 2. Yes, a rod out of alignment can score a cylinder bad. You don't just check to see if a rod is bent, or twisted, but check to see if the rod is off set, about 75% are.
No. 3. Yes, a crank will cause a cylinder score, if it is not centered. A quick way the check, is to see if the center main has a even clearance on either side of it, or a little larger spacing on the rear side of the center main.
No. 4. Yes, cylinders bored off may do it in the extreme, or with a combination of other things, in any case, it is not good.
Warwick showed me some photo's of Rose's engine on sunday. Sounds like a run down the road Dav and we will work it out.
I didn't want to trouble you, but l'm kinda glad l did, your work l must say is impeccable to say the least.
I'll pull the block have it sleeved and then give you a call.
I put my hand up for that Mike, as I'm all thumbs when it comes to computers, my wife, Kerry, put her name as a users name many years ago, I just left it that way, I just work on the theory of 'call me what you like just don't call late for dinner'
Changed it now to avoid confusion!
OK, Frank -- That explains it. And all this time we thought your name was Kerry.
I have been calling Frank, Kerry on this forum for quite some time. I have a chuckle each time I type it. I even tell Kerry she has been busy telling Royce off! She may not post herself but she still knows all the forum characters. It is great to have Frank nearby. He has done the bearings in two of my T's now and they both run great. I hope to learn the art of pouring and machining bearings from Frank some day soon. This is Franks and my 1916 Tourings 2 weekends ago on a local tour together. Learned something about Frank that day, he gets airsick!
I wasn't going or game to let the cat out of the bag, HEY FRANK, now we know who you are.... he , he ., he.