1.2 pistons

[_Jake]

at the moment im attempting to carry out the infamous 1400cc bitsy engine, guided by mowgli lol at the moment i already have a complete 1300 for parts, a spare set of 1300 rods, arps/e16se big valve head/40s etc. Now im looking at importing pistons from germany as ive tried a good few places over here and theyre non existant.

Found a shop that sells 1.2 pistons and they have two types; 12s & 12n.

http://i255.photobucket.com/albums/hh160/bodmin344/KGrHqJHJEcFDsO68twBQ9nKRKhrw60_12_zpsca4a86a1.jpg
12s ones which are 78.3mm and have valve cut outs like "normal" 8v's

http://i255.photobucket.com/albums/hh160/bodmin344/T2eC16dHJGE9nm3rI5SBQ9nK7Ft3g60_12_zpsaf6169f0.jpg
a different set of 12s ones, 79.5mm and almost flat topped. maybe ohv ones?

http://i255.photobucket.com/albums/hh160/bodmin344/T2eC16dHJG8E9nyfpndYBQ9nLBLcNg60_12_zps6b251801.jp g
12n ones which are 79.5mm and have a perculiar bowl in them, again i think there an ohv item but i could be wrong.

all share the 20mm gudgeon pin diameter so they'll work with my rods, but my question is what would be the better option? im thinking the nearly flat top 12s ones could be a good bet but may send the compression skywards? or maybe the 12n ones with the bowl machined fully as a circle rather than a half moon, i think this would have to be done pending what happens when i do a dummy run on the build as obviously im using big valves and a lairy cam.

before anyone swears at me for butchering a 13s block im currently hunting for a 14nv with the right starter mount for a f10 flywheel. lol

any help appreciated, but if you dont have any genuine knowledge on the subject please dont comment as i dont want to end up with some pistons totally useless to me! cheers :)

[chrisd1986]

tbh all the different style of piston is machined epecially for the correct valve clearance on the particular engine they are made for so you need to find out what your valve clearance is otherwise you will end up buying a compleatly usless piston for your engine

[Jon_nova1]

I'd personally go for the flat ones, i built an engine with 1.4 bottom end and a performance 1.2 head, there was so much taken off the head i had to dremel a small cutout in the pistons because the tip of the spark plugs got squeezed together when the piston reached tdc, i never had any issues with knocking etc

[mowgli]

use the top ones. they will give you about 11:1cr with a std 1200 head. the others are ohv ones & should be avoided simply on the grounds of valve cutouts being in the wrong place..

the 2nd pic is definitely ohv, but i really can't place the third one, its probably an ohv for a lo-comp spec.

like i said before, if your old 1200 pistons clean up well, just re-ring them. pistons last a long time. rings are designed to wear out.

[jimbob-mcgrew]

i built an engine with 1.4 bottom end and a performance 1.2 head, there was so much taken off the head i had to dremel a small cutout in the pistons because the tip of the spark plugs got squeezed together when the piston reached tdc, i never had any issues with knocking etc

lol - going for it john


use the top ones. they will give you about 11:1cr with a std 1200 head. the others are ohv ones & should be avoided simply on the grounds of valve cutouts being in the wrong place..

the 2nd pic is definitely ohv, but i really can't place the third one, its probably an ohv for a lo-comp spec.

like i said before, if your old 1200 pistons clean up well, just re-ring them. pistons last a long time. rings are designed to wear out.

mowgli's on it !