Looking for confirmation that my recently acquired Hepolite pistons 11546 for the XK 3.4 ltr engine don’t require a specific orientation because of an off set of the gudgeon pin. Cannot find any reference regarding the way to install these pistons. There is a lot of text on the top of these pistons but no arrow or F stamped. See pic. I’ve measured the position of the pin and it’s absolutely in the centre of the piston. Just want to be sure before I put the pistons in the block.
Bob K.
I have new oversized Hepolite pistons in my 3.8 engine.
Pistons are the same all around.
There is no reference how to install them, just installed them with the Texts Hepolite to the front of the engine.
Peter Jan,
Thanks for your reply: seems yours are identical to mine (meaning no off-set pins). I think it is rather strange that there are no Installation Instructions provided by Hepolite at all. One could say that if there is no indication, it means there is no particular installation orientation (under the motto “No news is good news”).
I understand that Hepolite is owned by Wassell Ltd of Lincoln (UK) since 2011 .In the past years the same company also acquired the licenses for other “famous” brands like Lucas and Girling.
The new company’s packaging is very good with a lot of reference to their past; all it lacks is an Instruction how to fit them, more in particular as the original Hepolite pistons did have an “F” or arrow because of the off-set gudgeon pin.
Bob K.
I would fit with the ‘Hepolite’ manufacturer’s text to the front also. That’s the tradition, if no markings.
Thanks Roger. That’s what I’ve done when I (pre)assembled pistons and conrods.
Still trying to find a satisfying answer. I’ve been reading old contributions on the subject and found some from my dear friend Peter Crespin who refers to pistons with offset pins positioned several mm out of the centre. One particular piston that was discussed for a 4.2 engine, had a .059 offset (1.5 mm).
For me this is an indication that if my Hepolite pistons were to have offset pins, I would be able to measure such a distance with a caliper. But as mentioned before, these modern Hepolite piston have no measurable offset and therefor require no “Front” marking and have no specific orientation.
Bob K…
Maybe it’s an issue that arose for the 4.2 and/or the change to solid skirt pistons?
Hi,
3.4 Hepolite pistons are without pin ooffset, 3.8 & 4.2 do use an offset pin.
Kind regards,
Paul
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Paul,
Thanks for confirmation of my assumption. As I also couldn’t measure any offset, I just picked one side and then positioned all of the pistons in the same direction.
Note the difference in weight of these Hepolite pistons (between 397 and 402 grams) on the picture below.
The difference in weight of the (still original) conrods was only 2 grams. Fortunately I could “balance” the effect of the weight difference of the pistons by selecting matching gudgeon pins which in the end brought all sets within 1 gram. See table.
Note: the darker areas on the deck are due to cleaning the water ways of the block with an acid; I taped off the cylinder part in the center.
Bob K.
| Cylinder No. | Conrod | Piston | Subtotal | Gudgeon Pin | Total |
|---|---|---|---|---|---|
| 1 | 851 | 399 | 1250 | 107 | 1357 |
| 2 | 851 | 399 | 1250 | 107 | 1357 |
| 3 | 850 | 402 | 1252 | 105 | 1357 |
| 4 | 855 | 397 | 1252 | 104 | 1356 |
| 5 | 852 | 399 | 1251 | 105 | 1356 |
| 6 | 851 | 401 | 1252 | 105 | 1357 |
| Average weight | 851,7 | 399,5 | 1251,2 | 105,5 | 1356,7 |
| Maximum | 3,3 | 2,5 | 0,8 | 1,5 | 0,3 |
| Minimum | -1,7 | -2,5 | -1,2 | -1,5 | -0,7 |
Told ya, your expertise would be of great value!
