The Ford Barn

Newc · 04-27-2020, 10:18 PM

Among the treasures found in the latest barn is a new set of pistons. 3 5/16" bore- flat top and inside casting no. J E52 also stamped LC the wrist pin heigth measured from the top of the pin bore to the piston top is 1.06" . they are 3 ring. thanks Newc

Ol' Ron · 04-28-2020, 12:59 PM

Not sure of the pin height, but they look like the Jans pistons we used back in the 50/60 sportsman ckass stock cars. $49.95/w rings amd very heavy

Bored&Stroked · 04-28-2020, 01:57 PM

Well, if you add 1/2 the pin diameter, then the compression height should be around that of a 4 1/8" stroke crankshaft - which is 1.374 or so.

I'd take a look on the inside of the piston and see if the top section looks like it was originally for a "domed" shape. Somebody may have milled the tops flat.

Post a picture of the inside of the piston as well as the top of the piston - would like to see what you have.

FYI: I've heard the term 'LC' to mean "low crown" as well as some have said "long crank" - both pertaining to a stroker piston. Typically the TOP of the piston is marked with the amount of 'LC' in the piston - like "3/16 LC" which is for a 4 1/8" stroke.

Newc · 04-29-2020, 09:19 PM

Hi all; Tried to get better photos, not easy so close. here goes stamped 3 5/16th LC STD and #6 so they may have been assembled and removed.

Newc · 04-29-2020, 09:22 PM

Wow; right over the L. C. is a little 1/8 For 4 1/8" stroker???? Newc

flatjack9 · 04-29-2020, 10:06 PM

Sponsored Links (Register now to hide all advertisements)

1/8 would be 1/4' longer stroke.

Newc · 04-29-2020, 11:38 PM

Now I'm a bit confused. A 1/4" stroker would be a stock Merc... Yes? I hope to do some checking cause I have the 4" Merc cranks around the shop. newc

Brian · 04-30-2020, 12:37 AM

Correct, that is for a 4" stroke crankshaft. Jahns piston, as described by ol ron
Normally dome top, dunno why its flat.

frnkeore · 04-30-2020, 12:52 AM

The standard Ford deck Ht is 10.437.

If your piston has a compression Ht of 1.374, if used with a 7" rod and a 4.125 stroke (1/2 stroke = 2.0625), that adds up like this:

1.374/.375
7.000
2.0625 (4.125 stroke)
--------
10.4365/.4375

= 284 CI

frnkeore · 04-30-2020, 01:01 AM

After posting, I just went back a re-read Newc's post.

His compression Ht is actually 1.435 (1.06 + .375)

So it looks like they are made for the std Merc crank of 4" stoke.

1.435
7.000
2.000 (4" stroke)
----------
10.435

275.75 CI

Ol' Ron · 04-30-2020, 10:01 AM

On a 4" crank the piston goes up 1/8: and Down 1/8" more that a stock 3 3/4 crank Thus the 1/8 LC

Bored&Stroked · 04-30-2020, 10:19 AM

Frank and others have it right - this is a 1/4" stroker piston - for a 4.00" Merc crank. What is interesting is that the tops are flat AND they have the original markings from manufacturing - so obviously they were produced this way. I'm not aware of any "flat chambered" heads for 39 - 53 flatheads (made back in the day) . . . so it is a bit of a mystery as to what they were used for (probably something custom).

Note: It is probably a J&E piston - which looks almost exactly the same as a JAHNs. Anybody know if both were made by JAHNs???

rotorwrench · 04-30-2020, 10:42 AM

I don't know about J&E but JE would be for Jahn's Engineering.
https://www.jepistons.com/about-us/our-history

Newc · 04-30-2020, 01:44 PM

Did I come to the right place! so maybe they are for a [supercharged] motor. 4" merc crank. Any rate I can use them. Yippee. thanks Newc

rotorwrench · 04-30-2020, 02:39 PM

Some folks liked to play with the heads. Navarro made some blank chamber heads where they could be modified for pop ups or different chamber shapes. The real early flathead V8s had flat tops, steel pistons, and various other differences. It's hard to say at this point in time.

estout81 · 04-30-2020, 02:52 PM

If those are Jahn's like we used in the '60s they weighted a ton. I'd offer them for recycle only!

Bored&Stroked · 04-30-2020, 05:17 PM

Quote:

Originally Posted by rotorwrench

I don't know about J&E but JE would be for Jahn's Engineering.
https://www.jepistons.com/about-us/our-history

Yes - I did a bit of research and they switched/evolved the name form Jahn's to just JE. Most of the older cast pistons that I ran had the name Jahns in them . . . guess I never bought any of the 'newer' versions . . . had probably switched to ForgedTrue by then (which is what a Ross forged piston mimics today).

frnkeore · 05-01-2020, 01:52 AM

I was looking through the HAMB parts threads and found this add, for Dodge Hemi pistons.

Do they look familiar?

As near as I could tell, the post mark is '74.

It looks like Jahns had a standard piston design, maybe for everything?

04-28-2020, 12:59 PM	#2
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Piston ID please Not sure of the pin height, but they look like the Jans pistons we used back in the 50/60 sportsman ckass stock cars. $49.95/w rings amd very heavy

04-28-2020, 01:57 PM	#3
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,064	Re: Piston ID please Well, if you add 1/2 the pin diameter, then the compression height should be around that of a 4 1/8" stroke crankshaft - which is 1.374 or so. I'd take a look on the inside of the piston and see if the top section looks like it was originally for a "domed" shape. Somebody may have milled the tops flat. Post a picture of the inside of the piston as well as the top of the piston - would like to see what you have. FYI: I've heard the term 'LC' to mean "low crown" as well as some have said "long crank" - both pertaining to a stroker piston. Typically the TOP of the piston is marked with the amount of 'LC' in the piston - like "3/16 LC" which is for a 4 1/8" stroke.

04-29-2020, 09:22 PM	#5
Newc Senior Member Join Date: May 2010 Posts: 2,484	Re: Piston ID please Wow; right over the L. C. is a little 1/8 For 4 1/8" stroker???? Newc

04-29-2020, 11:38 PM	#7
Newc Senior Member Join Date: May 2010 Posts: 2,484	Re: Piston ID please Now I'm a bit confused. A 1/4" stroker would be a stock Merc... Yes? I hope to do some checking cause I have the 4" Merc cranks around the shop. newc

04-30-2020, 12:37 AM	#8
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,834	Re: Piston ID please Correct, that is for a 4" stroke crankshaft. Jahns piston, as described by ol ron Normally dome top, dunno why its flat. __________________ Unfortunately, two half wits don't make a whole wit!

04-29-2020, 10:06 PM	#6
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Piston ID please Sponsored Links (Register now to hide all advertisements) 1/8 would be 1/4' longer stroke.

04-30-2020, 12:52 AM	#9
frnkeore Senior Member Join Date: Jul 2019 Location: Southern Oregon Posts: 782	Re: Piston ID please The standard Ford deck Ht is 10.437. If your piston has a compression Ht of 1.374, if used with a 7" rod and a 4.125 stroke (1/2 stroke = 2.0625), that adds up like this: 1.374/.375 7.000 2.0625 (4.125 stroke) -------- 10.4365/.4375 = 284 CI __________________ Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline

04-30-2020, 01:01 AM	#10
frnkeore Senior Member Join Date: Jul 2019 Location: Southern Oregon Posts: 782	Re: Piston ID please After posting, I just went back a re-read Newc's post. His compression Ht is actually 1.435 (1.06 + .375) So it looks like they are made for the std Merc crank of 4" stoke. 1.435 7.000 2.000 (4" stroke) ---------- 10.435 275.75 CI __________________ Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline

04-30-2020, 10:01 AM	#11
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Piston ID please On a 4" crank the piston goes up 1/8: and Down 1/8" more that a stock 3 3/4 crank Thus the 1/8 LC

04-30-2020, 10:19 AM	#12
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,064	Re: Piston ID please Frank and others have it right - this is a 1/4" stroker piston - for a 4.00" Merc crank. What is interesting is that the tops are flat AND they have the original markings from manufacturing - so obviously they were produced this way. I'm not aware of any "flat chambered" heads for 39 - 53 flatheads (made back in the day) . . . so it is a bit of a mystery as to what they were used for (probably something custom). Note: It is probably a J&E piston - which looks almost exactly the same as a JAHNs. Anybody know if both were made by JAHNs???

04-30-2020, 10:42 AM	#13
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,431	Re: Piston ID please I don't know about J&E but JE would be for Jahn's Engineering. https://www.jepistons.com/about-us/our-history

04-30-2020, 01:44 PM	#14
Newc Senior Member Join Date: May 2010 Posts: 2,484	Re: Piston ID please Did I come to the right place! so maybe they are for a [supercharged] motor. 4" merc crank. Any rate I can use them. Yippee. thanks Newc

04-30-2020, 02:39 PM	#15
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,431	Re: Piston ID please Some folks liked to play with the heads. Navarro made some blank chamber heads where they could be modified for pop ups or different chamber shapes. The real early flathead V8s had flat tops, steel pistons, and various other differences. It's hard to say at this point in time.

04-30-2020, 02:52 PM	#16
estout81 BANNED Join Date: Jun 2010 Location: Utica, Ohio Posts: 522	Re: Piston ID please If those are Jahn's like we used in the '60s they weighted a ton. I'd offer them for recycle only!