Piston question
 

Well, I'm finally getting back to this rebuild and have a question on the pistons. This motor is a 1948, 59a with a 8ba rotating system in it. The cylinders are stock/standard 3 3/16th as are the pistons. When I disassembled it, I did notice that there were two pistons unlike the others. They are like the one on the right in the photo. The rest are like the left one. I noticed the difference in thickness between the compression ring groves and the thinner lower ring grove on the one to the right. The right one also measures to be a slightly taller piston from the pin to the top. A couple of the other six say Mercury inside.

My problem now is trying to find two standard pistons to match the six I have so I can order the right set of rings. Anyone have a couple of these laying around? Haven't found anything in my search so far.

Re: Piston question
 

Opp! Here they are.

Re: Piston question
 

[QUOTE=DWester;996960] The right one also measures to be a slightly taller piston from the pin to the top. A couple of the other six say Mercury inside. QUOTE]

You say "slightly taller"......Does it measure 1/8" taller? If so, they ARE Mercury pistons for a 4" stroke crankshaft. DD

Re: Piston question
 

I think I would go and carefully re-measure the stroke on your crankshaft to verify what it actually is. 3.75" would be Ford, and 4.00" stroke is the Merc. DD

Re: Piston question
 

ford and merc pistons

Re: Piston question
 

Perhaps pre '48 Mercury pistons? Back in the 50's and 60's, we would mix and match junkyard pistons as long as they weren't cracked and were nominally to size with very few problems (flatheads can be very forgiving). That being said, I think in this day and age, a new set of pistons is in order, since some of these have probably been in and out of an engine(s) more than once.

Re: Piston question
 

I think you will find if you stick one wrist pin into each piston you'll find both pistons the same height, if there both the same height you still have to measure the stroke to get the right piston. You might have a hard time matching a piston, there usually a lot different in weight. If there difference weight they usually cause a vibration. Walt

Re: Piston question
 

I have a set of 8 standard pistons with pins that I removed from a running engine. 4 pistons are marked on the inside "Ford made in Canada" and 4 pistons are marked 2F9. If interested send me a PM. (3 3/16")

Re: Piston question
 

Thanks for all the replies. To be honest, this motor will be going in an old farm truck that will get maybe 200 miles on it a year. It's not mine, it's something I'm trying to help out for a friend of mine who feeds hay with. There's nothing more I'd like more than to be doing a build with all the new parts and end up with a really nice flatty. That's just not the case this time. I'm just trying to get him up and running with a decent running motor without spending too much $, yet something that will keep him feeding cows for a few years more.

I've done a stroke test and it's definitely 3 3/4, not 4. I'll just have to find two standard pistons or a set, whatever comes first.

Thanks so much for your response,

Darol

Re: Piston question
 

contact Reds Headers, I am sure they can get you a couple of pistons and new rings. http://www.reds-headers.net/

Re: Piston question
 

Darol, I might have a couple of good used std. full skirts pistons, the rings are usually 3/32-3/32-3/16-3/16 you can have them just for shipping, I won't have a chance to go to my storage barn today but maybe tomorrow. The barn is 500 feet from my house and the snow is getting deeper. walt

Re: Piston question
 

That sounds great Walt! So, if I ordered a set of rings for the pistons I have six of, will the rings also fit the pistons from you?

Re: Piston question
 

Most of the pistons have that size rings, some early pistons had a different size I cain't remember, can you mic the rings? Walt

Re: Piston question
 

I'll do that Walt and get back to you. Are they the 3 or 4 ring pistons?

Re: Piston question
 

You might try what Walt suggested, put one wrist pin to two pistons, if they're the same height, weigh them... If they are close- run them as is...

Karl

Re: Piston question
 

I wanted to do that, but the two pistons that are different require a different set of rings. In my picture above, you can see that the one on the right uses slightly smaller oil rings than the others. I figured it would be a PITA if even possible to get rings for just two pistons that were different from the others. Maybe I'm wrong???

Re: Piston question
 

Measure the groove widths and report back to us.They should all be the same.

If not the 2 pistons appear to be from a 46 to 49 59a. (5/32 oil rings).

R

Re: Piston question
 

OK. On a dial caliper, the two different pistons (on right) measures .256. The left one is .285. This is the oil ring groves only. The compressions are the same. So the six I would like to use have a slightly larger oil ring grove. Which of these are odd ball?

Re: Piston question
 

Those measurements don't seem to match what 8ba and 59a engines have for oil ring widths. They should measure either .1875" for 3/16" or .156" for 3/32 have you measured accurately?? Your measurements are over 1/4" How about .
.156" and .185" looks like a typo (confirm)

R.

Re: Piston question
 

Sorry Ronnie. I tried to get back to correct that, but you beat me to it. Yes, the correct #'s would be .185 and .156