Hi looking to price up line boring an l18 block for an l20b crank.
Just wondering on any recommendations and prices in mrlbourne.
Maybe a possible 2 mm bore too but might keep it 85mm

Try Ferco and speak to Peter (greek dude) no one else

cavehill engine. lilydale. Stu knows his stuff

Cheers. Spoke with one I know don trusts. They recomended grinding crank to fit the block. Max $200 balanced and linished.
Sounds like a better plan then can use different block in future.

Thats an excellent price inc. balancing
get the bore pricing as you are getting
new pistons anyway might as well go the
longer rod and get the benefits

Do what you're best at Mik and offer blowjobs for machine work. Show them that trick you do with the horse.

Benny spoke with stu. He grinds crank down but uses after market rods and forged pistons. He knows his stuff but way outta my budget.

Im only looking at a streeter or club car not a full racer.

Rod angle of 19 deg might be an issue to bore it. Might put too much side load on bores wearing pistons and bores prematurely.
L20 crank with l18 rods and z20s pistions says 11cr
Thats 85mm bore and 2lt. Should be grunty but not revvy.
Might be better making a revvy motor for track. L18 crank l16 rods and z20s pistons... vroom vroom

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Yep. And you're close already. L18 crank, L16 or L24 rods, and mill the L18 pistons for the desired deck height. you can also shorten the skirts a bit if you want. That's what we've been doing for decades up here, and what was in my old L18 coupe. Junker motors FTW! With a 76 cam grind and a peanut chambered head with very minor tickling (polished standard valves, tapered guides and minor pocket area work) and twin 40mm sidedraughts it made 116rwbhp and was a regular 1601-2000cc class winner. You'd get alot more out of it with a better cam and proper headwork.

No sense spending the coin to get an L20 crank in an L18 block unless you are forced to use an L18 block for historic racing. Just drop the whole L20 in there. Better rod/stroke ratio standard. Much better again with Z20 internals...

How much milling do the pistons tend to need

depends what CR you want ;)
It was a long time ago, but I think I took about .080" (2mm) off for about .010" positive deck height - ie piston crown above block height at TDC. With my cyl head that gave about 10.8:1 CR IIRC.