What are these strange Pistons?
 

I've got 35 of them, obviously used, in a box. One piston has 99A-6108 written on an attached tag. They do match the dimensions for a 3 3/16 bore engine and if I am correct that part number is for a 239, but they are obviously not Ford pistons and don't have any part numbers or identifying marks on them other than the one tag.

Any ideas?

Re: What are these strange Pistons?
 

Ford steel pistons. Yes, they are genuine Ford. I like them, they are very light weight.

Re: What are these strange Pistons?
 

99A denotes 39 Merc which is a 239 engine. I have several of these on the shelf removed from a 40 Merc engine

Re: What are these strange Pistons?
 

Interesting. I would have bet someone else's reputation that they weren't Ford parts :D

They sound cool when you tap them together. Maybe they would make a nice wind chime :)

Thanks for the info, gents. Much obliged.

Re: What are these strange Pistons?
 

Those pistons were installed in the engines with the thin steel sleeves.

Re: What are these strange Pistons?
 

A friend had 39 Merc, took the car to a small garage to rebuild the engine, they brought the block to another shop to be bore, the block had tin sleeves, that shop was'nt to bright, they started to bore with a boring bar, the chips came out with a long string, so they honed the .040 thick sleeves with a Sunnen CK10 automatic honing machine to .030. The engine had the iron piston, they replaced them with heavy aluminum pistons. The first small shop built the engine and installed them in 39 Merc, it run good but had a vibration, they asked me to lissen to it, I told them at this point I'd pull the Clutch and PP and have check it for balance, the balance good so they stripped the engine, and had it all balance, the balance man had to do alot to the crank on account the aluminum pistons was alot heaver than steel pistons. Walt

Re: What are these strange Pistons?
 

So Walt...Let me see if I've got this right- the shop took the .040 wall sleeves out to .030" oversize, meaning the walls of the steel sleeves now were .025" thick? And they didn't collapse? And that engine then ran like that?

Re: What are these strange Pistons?
 

One could paint them different colors, run a ribbon thru their pin holes, and string them on a Christmas tree (just trying to inspire some Christmas spirit here).

Re: What are these strange Pistons?
 

I have a nos set of them.

Re: What are these strange Pistons?
 

Brian,
I see you called them "steel" pistons, I've seen lots of folk refer to them as iron. I believe your correct, as when I've had to beet them out of a seized up mess, the beeting they take is incredible. Much more than the aluminium pistons.
Martin.

Re: What are these strange Pistons?
 

Yea Brian, they honed ,030 out of the sleeves, and as far as I know the car is still running with the aluminum .030 pistons. I've removed many of the tin can sleeves and bored .045 and used Std 3-3/16 pistons it makes a good little engine with the A heads. Everdently the .025 sleeves fit tight in the thick block walls, I would never do it. Walt