As the title says I have my L24 bored 1mm over and pistons. I also have rebuilt N42 with new valves.

Anyone tried this combination with a N42 head? Any valve clearance problem found?

1 mm over would be about .020" per side.  The L26 bores are notched for their bigger valves from the factory, apparently.  Seems like you'd need to do some clearancing.

Here's a Hybridz thread on a similar issue to yours.  @madkaw has done some notching.

http://forums.hybridz.org/topic/70734-notchingbevelingbutterfly-l24-block-for-valve-clearance/

Notch your bores for breathing and piece of mind - it’s easy peasy

2nd that. It's easy with a die grinder and sanding flapper wheel.

I put my head on the block, chucked the intake valves onto my drill and eased them down into the bores. That scratched enough to know how far I had to grind back. Sorry I don't know the size to tell you for setting N42 on a 1mm over 2.4 block. You might find out reading a bunch of bulls**t but I'd feel better doing your set up "hands on". Not going by internet "alternative facts".

After more reading I found some posts saying a .040 overbore will clear the ex. valve.

They were referring to the L26 head mostly, but the N42 has the same size valve. However the N42 has the larger intake.

Not sure about that clearance.

I do have a shaved L26 E88, so I will just use that head. Wont  be able to tell the difference anyway I guess.

This is going to be put back together as a numbers matching block for resale value when I sell it. 

Hopefully I will not have to do that for sometime yet. Age, it gets harder to get in and out of the car every year.

I have heard the 1mm oversize is not a problem with the 35mm exhaust valve, but I would still do what Siteunseen mentioned and test it for myself.

Notching is not hard to do and on a 1mm oversize it would be minimal.

I would prefer the N42 head ovrr the L26 E88. The L26 E88 head has emmision chambers and is considered the lesser of the E88 heads. They made some improvements to the chambers on the N42 when they went over to efi.

Actually there is very little difference between the n42 and late e88 in the L26 . The only difference is the N42 has the bigger intake valve .Same chamber size on both.

Better clear it yourself or the valves will take care of it

I used a simpleton way to test. Put the head on a bare block and dropped the valve's. If they didn't fall though I'd remove a little more until they dropped free from the head to the bottom of the bore. I held each valve up with clothes pins.

Easy peasey when you're bored and it's cold out.  It runs so good and such fun with the E88 I've never gotten around to putting the bigger valve E31 that I did all this for. 

You need to get your head on straight Cliff -lol

put that 31 on there! Shave some more off of it first just for the hell of it. 

Nice pic above , but also point out that is probably the stock intake valve which is only 42mm , so that side will be tight also when using the bigger valve N42