Heplex pistons

It is not in my list below. Check inside the piston for other numbers. Anna D has most of the books with the manufacturing numbers.

600 7.4 L14/702

600 7.4 19406/19407

600 8.25 (7.4) 13325

600 8.95 18549

600 10.0 13408 (Became P/Max 18459)

600 10.2 18553 (650SS Piston)

600 9.0 21339/21340

600 7.4 (7.6) 22512/22513

600 8.0 22518/22519

600 8.25 23182/23183

600 8.9 23189/23190

600 10.2 23187/23188

650 8.9 17839

650 10.2 18553 (Later 650SS Piston)

650 8.9 24022/24023

650 ? 25387/25388

Previously phil_hannam wrote:

It is not in my list below. Check inside the piston for other numbers. Anna D has most of the books with the manufacturing numbers.

600 7.4 L14/702

600 7.4 19406/19407

600 8.25 (7.4) 13325

600 8.95 18549

600 10.0 13408 (Became P/Max 18459)

600 10.2 18553 (650SS Piston)

600 9.0 21339/21340

600 7.4 (7.6) 22512/22513

600 8.0 22518/22519

600 8.25 23182/23183

600 8.9 23189/23190

600 10.2 23187/23188

650 8.9:1 17839 /17840

650 10.2:1 18553 (Later 650SS Piston)

650 8.9:1 24022/24023

650 9:0:1 25387/25388

First 650 The Norton Manxman export to USA Only piston part numbers ( BHB) 23268LH& 23269RH & 23270LH & 23271RH over sizes to +30 only

Yours Anna J

Previously philip_chester wrote:

I have acquired a set of NOSNorton 600 pistons [ Heplex ] with the reference on the box end of 16362 but I can find no reference to this number in any of my literature. Could anyone inform me of the compression ratio for these pistons if they can cross reference them? Many thanks, Phil Chester.

yes there Heplex 7.4:1 with expanding shirts type yours Anna J

Certainly not 7.4:1 (usual caveats - depends on the cylinder head of course). Looks more like 8.5:1 or thereabouts. With petrol being what it is these days, I'm not keen on running much above 7.5:1 though I appreciate that low compression pistons for Norton twins aresomewhat scarce.

Attached photo shows my collection of spare 99 pistons. Ranging from standard bore up through +20, +40 to +60 thou.

The three on the left are all Heplex 13408...the +60 is an AE 16606 item. I think that all of them have the 413 and 613 numbers inside.

All the crown heights are the same give or take a thou. I would say that all of these are around 9 to 1 compression...possibly a little more. The final compression ratio depends on the head. The pre-SS/22707 heads usually being lower compression whilst using the same pistons.

As these pistons look very similar to those from Phil Chester, I would find it difficult to accept them as 7.4:1 CR. Unless they were flat topped. Which they are not.

Attachments
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Previously philip_chester wrote:

Hello,

Many thanks to you both for your time and efforts but I am surprised at Anna's assertion that they are 7:4 to 1 ratio. They are slightly domed with much larger valve pockets when compared to a flat top 13325 pictured alongside. Looking inside a piston the only markings are on the gudgeon pin bosses with the AE logo and 413 at one end with 163 and 62 at the other. It is always possible the pistons are not in their original box etc but the " Vacrom " coating which is still visible on the top ring and the circlip packet gives some validity. i reckon they are a bit higher than 7:4 to 1 so it is over to you guys to shoot me down in flames.

Well since our telephone conflab have done some searching and up to date come up with NO data on pistons Numbers 16362 So me thinks they could be export pistons for the Nomad as it had high compression piston of 9:1 ratio but we keep looking but if anyone out there as some information on these BHB/Hepilex Pistons we love to know for the records Yours Anna J Dixon