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04-27-2020, 10:18 PM | #1 |
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Piston ID please
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
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04-28-2020, 12:59 PM | #2 |
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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
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04-28-2020, 01:57 PM | #3 |
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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, 09:19 PM | #4 |
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Re: Piston ID please
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.
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04-29-2020, 09:22 PM | #5 |
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Re: Piston ID please
Wow; right over the L. C. is a little 1/8 For 4 1/8" stroker???? Newc
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04-29-2020, 10:06 PM | #6 |
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Re: Piston ID please
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04-29-2020, 11:38 PM | #7 |
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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
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04-30-2020, 12:37 AM | #8 |
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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.
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04-30-2020, 12:52 AM | #9 |
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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
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04-30-2020, 01:01 AM | #10 |
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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
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04-30-2020, 10:01 AM | #11 |
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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
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04-30-2020, 10:19 AM | #12 |
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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 |
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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 |
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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
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04-30-2020, 02:39 PM | #15 |
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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.
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04-30-2020, 02:52 PM | #16 |
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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!
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04-30-2020, 05:17 PM | #17 | |
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Re: Piston ID please
Quote:
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05-01-2020, 01:52 AM | #18 |
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Re: Piston ID please
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?
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