The issues caused by decking the block and milling heads to me are not worth the trouble they bring.

D I appreciate the information but I'm looking for off the shelf parts. I'm looking to get the max performance from what parts are readily available, if that maximum is a few horsepower less than custom parts so be it.

It looks like 76.75mm pistons are available via eBay, they appear to be the 1mm deep,dish which are around -2.75cc and with those it's possible to get the compression up to 10-1.

The goal is to get a near as possible 1300cc putting out around 90whp. The 1171cc GX motor with the flat slides and ported head made 73whp, so I think it's doable.mthe motor going in the car now is probably near 80whp.

I won't be doing anything until after my next race; I previously made the top 6 overall in the small bore group with the A12, I was finishing 12-15 seconds ahead of the cars behind me and about 12-15 seconds behind the cars ahead of me. If I manage the top 5 or 6 then I will leave the motor alone unless I'm within 4-5 seconds of the next group of cars

the Isuzu ones are 28.5mm thats 4-5mm less than the discussed items
they handle boost well, are lighter and shaving block 4-5mm should
prob? not be an issue as A12 engines are thickly casted units.

Id check if PJZ has longer rods available as I recall he had some
126mm rods available at one stage which could be fiat units.
They would allow the A12 with A13 capacity to raise the redline

Fiat 500 126mm rods x 2 sets are cheap from alibaba or aliexpress

https://www.aliexpress.com/item/connec ... E&ws_ab_test=searchweb0_0,searchweb201602_2_10065_10068_319_10059_10884_317_10887_10696_321_322_10084_453_10083_454_10103_10618_10307_537_536_10902,searchweb201603_6,ppcSwitch_0&algo_expid=ebf4f576-c333-4ba2-bc44-b1207b3158ca-1&algo_pvid=ebf4f576-c333-4ba2-bc44-b1207b3158ca

same but doubled in price
https://www.maxpeedingrods.co.uk/high- ... necting-rods-conrods.html

specs are almost spot on to A12 rods

https://www.hurricanerods.com/products ... steel-connecting-rod.html
Engine: Fiat 500 Abarth Punto 1.4L T-Jet
Part Type: Connecting Rods
Center to Center Length: 129mm/5.079"
Big End Bore Diameter: 45.13mm/1.777"
Big End Width: 21.7mm/0.854"
Small End Bore Diameter: 18mm /0.709"
Small End Width: 21.7mm/0.854"
Beam Style: H-beam
Connecting Rod Bolt Diameter:5/16"
Approximate Connecting Rod Weight: 415g/piece
Advertised Horsepower Rating: 550hp
Quantity: Sold as 4 pieces /set
Material: Forged 4340 steel
Connecting Rod Finish: Shot-peened, Polished
Pin: Bronze wrist pin bushings
Wrist Pin Style: Floating
Cap Retention Style: Cap screw
Weight Matched Set: Yes ,Balanced +/- 1g
Magnafluxed: Yes
Private Label: Yes ,available
Custom design: Yes, accept
Rod Wrist Pin Style: Floating
Small end diameter:: 20.005mm
warranty: limited lifetime warranty

Saw these on ebay , they have a tiny lip and depending on cost , could be shaved.

https://www.ebay.com/itm/222265879138?ul_noapp=true

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Yes J-series uses flat-top pistons

* J15 has 39.8 pin height so will stick up out of the deck 7.3mm

* J18 has 31.9 pin height (0.7 lower than A12A/A14) but is 80.5mm diameter and uses a larger pin

* J13 has 32.5 pin height same as A12A and is flat-top, nearly same as A12GX but different skirt design -- smaller bore than A12A

75.5 bore, 32.5 compression height, short-skirt piston

Nissan K15 used in Nissan and Mitsubishi forklifts

pin bore is 20mm, instead of the 19mm of the A-series, so a small mod would be required

* $20 https://venusparts.en.alibaba.com/prod ... r_Nissan_12010_FU320.html
* http://www.k21engine-parts.co.uk/cont ... Crankshaft___Pistons.html

There are also dished versions of the K15 piston

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  Nissan-K15-engine-piston.jpg (55.69 KB)

A shot in the dark
does J15 fit , they use a flat top , think a lower comp. then deck the block ??

4.5mm is not much off the top of the block
especially if you use studs with locktite

18mm pins is spot on for old rods

No effort needed -- just buy the off-the-shelf pistons

Peter Z has no flat-tops, at least none right now listed on his web page. In the past he usually had domed pistons but is now recommending Wiseco customs

Note that flat-tops make more power than stock dish-tops do, even when the compression is raised by decking the head. Decking the block works well if the pin-height is too low. Block decking also works to improve quench area -- but then so does a thinner (competition) head gasket

This seems a lot of effort sourcing a piston . Either deck the block or shave the head. I would go the block as they are easier to source / cheaper to buy, than a head now adays. Peter Zekert may have a set of used forged if you are definite on the piston option

Wrong pin height. A12A/A12/A13/A14 pin (compression) height is 32.5 mm

That leaves only one choice: off-the-shelf 77mm Kameiri pistons available now