59ab flathead piston issue?

[BillyBobsSpeedShop]

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/p...ctureid=325061

[Russ/40]

Run it, you will never know it's there. Looks like damage that was done before installation. Probably the pistons were used in a prior motor before being used in this rebuild. What is the bore measurement? Are the pistons marked oversize? Did you do a compression test?

[Chris Nelson]

Pictures would sure help the discussion.

[BillyBobsSpeedShop]

Chris,

Picture is in the link

[AlDeBear]

Oh No!!!!!!!! I've gone blind!

[tiquer]

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Pulled one apart like that had broken rings(top compression)

[bobH]

Originally Posted by tiquer

Pulled one apart like that had broken rings(top compression)

Me too... In my case, the engine had been doing some pinging, and there were a couple of questionable pistons (as viewed from the top, pistons still installed). I found FIVE broken top rings. I replaced the questionable pistons, and replaced the rings, and have now been running the engine for about five years with no problems.
BTW, that 'burned-away' mark shown in the picture, is very much like what I observed in my own engine.
Just my opinion...

[Ol' Ron]

Well the esiest thing to do would just runit. Or you could remove the oiston and look at it, If nothing is wrong with it, put it back in and run it. Or you could spend several thousand dollars on it and run it. Me, I'd run it.

[Shu47]

I agree with Ol' Ron. If this is the only issue then just run it.

[bobH]

Here are a couple of pictures of pistons removed from my own 47 Ford with 59A engine. This is from a STOCK engine, standard bore. This is from the 'pinging' engine that I mentioned above, from which I found five broken top rings. My question... What is shown in the 'subject thread', the same? Is that a burned piston, shown in the original picture?
(click on pict, to enlarge view)

[jimTN]

I am with Bob although I could not get that jalopy thing to work so I have not seen the actural picture. I have torn lots of well used engines down with broken ring lands like Bob shows above.

[Karl Wolf]

I would pull two pistons, I think your top ring grooves may be bad... Certainly the one you've pictured has a broken top ring.... If I'm wrong, just replace the one bad... If you want to go real cheap, let me know what size bore- nothing saying you have to go for a rebuild... (I would) Maybe that I or others could donate a set of used/useable pistons... Having the thing come apart on you could be a bit more money and trouble... Karl

[BillyBobsSpeedShop]

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. everything else in the engine looked great. The bottom end is very clean no wear on the rod ends or the bearings.

Thanks
everybody

[Russ/40]

Well, I guess a lot of us were wrong on this one. Happy that you mde the right choice.