I have a 59ab flatty that came out of a running welder. I witnessed the motor running and it seemed to run fine. I pulled the intak and the valve train was really clean. I then pulled the heads off and all the pistons looked good except for one. I notice what appears to be a chip on the edge of the RH side read piston. It looks to be just on the edge of the piston. The bores feel smooth throughout the engine. I looked at the bottom of the head and there was no place the piston hit, no marks or anything? I looked at the valves and they all seem good and there was only carbon build up on the piston and the adjacent valve. There was no piston fragments. The mark doesnt look to be fresh and looks out of place, could this flathead have had this mark in it this whole time and run fine? The motor is in good shape and there is no cracks that I have found in the block. I was originally going to just slap on a pair of edelbrock heads and edelbrock intake that I have and run the engine and not sure if I should now. I called a couple guys today and last night and one is a flathead builder and he said it should be ok from what I was describing to him but he hasnt seen it. He said if it doesnt appear to have hit anything then it may be ok. Another guy said I need to replace the piston, I respect both of their opinions and am taking both into consideration. I am not trying to build a stump puller just want a nice cruiser but would hate to have major problems down the road. I was told the engine never gave he guy a problem and he had never taken it apart, and from me taking it apart it seemed very tight. All suggestions will be very appreciative. I would like to to just run it as it but not sure. Thanks http://www.jalopyjournal.com/forum/picture.php?albumid=16650&pictureid=325061
A cardinal rule of engine assembly is close inspection of pistons. Proposed feet per minute of travel would dictate that their condition be excellent, and held to one standard. (this includes all of them) If you are 'not sure', just imagine that box checked on a Quality Control build sheet. Balancing them is the final step...
A picture would help ! Some pistons have a notch on one edge to show the direction for correct fitment in the engine.
I'd replace it and check all the others. It could be that the piston shown has broken rings. Just my opinion. Jim
If hot gasses start passing by that spot when the ring gaps line up there, it will burn little bits of the cylinder wall away and that's even if the ring is not broken. Some folks say the rings don't turn in the grooves. They haven't met Murphy yet. I have a block with some burned out grooves in the wall where a ring broke so I know it can happen. The damn thing would still pull near 30 psi of compression even with the compression gas going through there.
Looks like you have broken rings in the left upper corner in the pic you can see a black spot on top the cylinder wall where the ring dont have scraped the soot away the probabel cause to the damage is probably ....... spark knock, pinging ore what ever ts caled in english
Billy, I'm not trying to sound like a butt head here, but flatheads are numbered 1 to 4, front to rear on the U.S. car passenger side, 5 to 8, front to rear U. S. car driver's side. You people "down under" will have to figure it out on your own. Do you have any buddies with some like size used pistons? I'd replace that one and then run it. You can worry about balancing and all that on a complete rebuild.
I pulled the piston with ease and the first ring in the piston was bad. So I am needing a STD piston for my 59ab flatty if anyone has one laying around