Rumble1960 Posted March 22, 2009 Report Posted March 22, 2009 I'm going to post a couple of pictures of cylinder #4 and 5 of my flathead, it's a 1960 Sweptline pick up with 72000 miles on it. These two cylinders both have some spots that are actually indented into the wall, can anyone comment on what could have caused this, they had about 120 psi compression taken just before disassemble started. Pistons and rings look good and felt tight in the cylinder, I was hopping to hone the cylinders put new rings on and reseal the motor, which is why I took it out, it ran good but leaked oil. How do you guys recommend I precede from here? Quote
Joel Torres Posted March 23, 2009 Report Posted March 23, 2009 don't they like bore it out and sleave it in this senario ? or bore and use bigger pistons? Quote
Young Ed Posted March 23, 2009 Report Posted March 23, 2009 Just me but I say if it was running good before seal your oil leaks and run it some more. Quote
aero3113 Posted March 23, 2009 Report Posted March 23, 2009 I had the same type of marks on my #2 and #4 cylinders. I did have some broken rings and figured that is what caused the marks. I just honed them the best I could and put it back together. So far its been running great Quote
Norm's Coupe Posted March 23, 2009 Report Posted March 23, 2009 don't they like bore it out and sleave it in this senario ? or bore and use bigger pistons? That's what I would do if it were mine. That way I'd be sure nothing got past the rings. That looks too deep just to hone out. Quote
JIPJOBXX Posted March 23, 2009 Report Posted March 23, 2009 Looks like it might be something in the gas? Maybe its something to do with ethyl alcohol in the gas? Looks like the cylinder is blue in color is that right? I almost would say just hone it out and reinstall the pistons with new rings. They probably stop below where that wird finish is. Or could of someone put some nitro in the fuel??? That is a strange problem. Quote
Joe Flanagan Posted March 23, 2009 Report Posted March 23, 2009 If that area is above the piston's highest position on the compression stroke, is it a problem? If it's running well, I'd be tempted to leave it alone. I WOULD find out what caused that, but because of its location it doesn't look like it would interfere with oil, compression, or anything else. But there are much more experienced guys here who can weigh in. Quote
Norm's Coupe Posted March 23, 2009 Report Posted March 23, 2009 The others could be right about the position of that bad spot not causing a problem. But.........here's my take on it and the reason I would have that bored out and install all new pistons. You already have the engine half torn down now. If you just hone it, put new rings in it and put it back together, then have a problem there, you'll have to tear it all down again anyway. Then you'll still need to get it bored out and install over sized pistons. You are not only doing the work twice, but also spending the money twice. It's not that much more work to just pull the engine, have it bored, put new pistons in, new valves, etc. Then you know you have a good engine that will last a very long time. Valves, keepers, etc. don't cost that much more. The only extra money spent will be for things like the machine shop and pistons. Actually, that bad spot could have come from rust too. If the engine had sat for a long period of time with coolant on top of the piston, that could have caused that bad spot. If that's the case, no telling how deep that bad spot really is. By having it checked out at the machine shop prior to boring, you'll know if that is just as deep as it looks, or deeper. If it's too deep, it's probably not even worth the effort to put new rings into it. My brother in law rebuild a Flathead Ford V8 engine several years ago. He didn't have the block checked out. After the rebuild of the engine and filling with coolant, one of the cylinder walls leaked. So........that was about $1800 down the drain, plus the time involved. He was able to pull and use most of the new parts he put into it for another engine. But.........he still had to do it twice and get another block. The bad spot in his first engine was so small you could not see it with your eyes. Quote
blueskies Posted March 23, 2009 Report Posted March 23, 2009 I'd bet your pistons look like this... These came out of my 218, with 86 thousand miles on them. No smoke, and it ran fine. And my cylinder walls were clean too, no pits or streaks. I'd bore it 60 thousands over and replace the pistons if it were me... As Norm said, with the engine out and the head off, your half way there anyway. Pete Quote
Beallrite Posted March 23, 2009 Report Posted March 23, 2009 That looks like corrosion pitting (rust).If it were me I'd put a mic on it and try to get a idea of how deep it is , then you'll know if a overbore will take it out .Your compressions good ,I would put it back together,fix the oil leaks and run it until I had enough cake to rebuild . Save the rings for the rebuild. Quote
Rumble1960 Posted March 24, 2009 Author Report Posted March 24, 2009 No broken rings and the pistons look great, I will mic the cylinders and see how deep the spots are and decide what to do. I know a re bore oversize would be best but expensive. Quote
blueskies Posted March 24, 2009 Report Posted March 24, 2009 No broken rings and the pistons look great, I will mic the cylinders and see how deep the spots are and decide what to do. I know a re bore oversize would be best but expensive. Wow, I'm surprised that the pistons and rings are so clean... I've seen half a dozen different engines with pistons like mine.... Pete Quote
Rumble1960 Posted March 24, 2009 Author Report Posted March 24, 2009 Wow, I'm surprised that the pistons and rings are so clean... I've seen half a dozen different engines with pistons like mine....Pete except for those odd spots on the cylinder walls this 49 year old engine is in remarkable condition. The rod bearings look as good as new, this was a one owner vehicle until a couple of years ago and has always been on non detergent oil which is a testament to its ability to protect engine components. Quote
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