can anybody possibly tell what is the maximum for boring out an a12 cheers

76mm is a reasonable safe overbore.

if you wish to go bigger you will need to sonic test block.

what combo are you thinking.

hey bige,
Roughly how much is it to sonic test a block?
and also to "prep" it up for 76.76mm pistons?

and 73dat1200, i've read of a12s being bored to 76.8mm.

cheers

depends on where you go, how good they do it, its approx $35+ per bore for sonic testing.
each bore should be checked in 8 different points. (min)

I fitted 77.5mm flat top pistons to my A12 race motor with no problems which brought it up to 1321cc and it goes harder than the 1400 it replaced.It produces 90hp at the wheels at 9200rpm.
Probuilt at 20/38 Kendor st Arundel did a good job the main guy there has done many A series motors over the years.GREG

thnks bige,

vixen,
I've Never heard of 1321cc a12motors but always learning from thise site.very impressive to run 9200rpm revs.Just out of curiosity how did the engine "drive" while not on track?i.e street driving conditions?im aware u stated its a race engine....

ive searched on site and got article on a12a running 77.5mm pistons.would a 1321cc a12 be let to run in the 1300cc class?
so is that the 77.5mm max bore?

Anyone got any links to reputable a-series engine builders in vic?
cheers

a a12 with 70mm stroke, with a "77.5mm" bore = 1329cc(SORRY "1320CC" PUSHED 9 NOT 0 LAST FIGURE) thanks to vixen for picking that up.

stroke/bore
70mm x 76mm = 1269cc
70mm x 76.5mm = 1286cc
70mm x 77mm = 1303cc
70mm x 77.5mm = 1320cc

if you class is 1300cc max and under, then 76.5mm is the go.

hope this helps,

i can help if you please. pm me

i'm building up an automatic a12 i just got my cam back from camtech cams and now i'm sending the head away and then get the cylinder bored out but i'm just worried about the water jacket thanks for that guys