Slight discoloration on cylinder walls towards the top (see pics)

[McGyver]

Was your build the same as mine (budget stroker) or just an M20B25?

Same build with essentially the same goals.

Phase 1 - M20b27 with 9.5:1 Compression, 280/274 cam, adjustable cam gear, custom Mark D chip, RD Headers, Stromung exhaust

Phase 2 - Add Megasquirt 2 with wasted spark

Phase 3 - Turbo

[jc1000]

Same build with essentially the same goals.

Phase 1 - M20b27 with 9.5:1 Compression, 280/274 cam, adjustable cam gear, custom Mark D chip, RD Headers, Stromung exhaust

Phase 2 - Add Megasquirt 2 with wasted spark

Phase 3 - Turbo

Nice! Did you deck the block at all?

I have another thread here where I was trying to understand what I need to tell the machine shop so they know exactly how much to take off the block. Do you have any advice on that?

[McGyver]

Nice! Did you deck the block at all?

I have another thread here where I was trying to understand what I need to tell the machine shop so they know exactly how much to take off the block. Do you have any advice on that?

I did. I had them Clean the block, check for cracks, cut the main caps and align hone (using ARP Studs), use a torque plate to bore and hone the cylinders 0.50mm over (using ARP Studs), deck the block about 2mm to restore factory quench (using a stock gasket).

I already had the crank magnafluxed for cracks, polished, and balanced. Connecting rod caps were cut and big end was bored (using ARP bolts), small end honed. Head was checked for cracks, new valve guides, new valve stem seals, 5 angle valve grind, surfaced the mating surface.

[jc1000]

deck the block about 2mm to restore factory quench (using a stock gasket).

What did you tell the machine shop for them to get this exactly right?

If you take them the head and a stock gasket, will they know what to do from there? And does it depend on the cam selected?

digger said on this thread that the squish is 1mm +- 0.1. Is that what you used?

[McGyver]

What did you tell the machine shop for them to get this exactly right?

If you take them the head and a stock gasket, will they know what to do from there? And does it depend on the cam selected?

digger said on this thread that the squish is 1mm +- 0.1. Is that what you used?

If you're going to use ARP studs, they'll need the studs. Otherwise, they can use the old head bolts for fitting it.

I took them the head and sent them a new head gasket because they didn't have a used on one hand. They were told to measure the assemble the rotating assembly with the 81mm crank, 130mm rods, and new pistons. Then deck the block to bring the piston to deck height back to the stock measurement. I don't know if they measured, but I plan to measure everything as I begin to assemble it.

Honestly, a competent shop will know how to approach it.

[digger]

there is a difference between factory squish clearance vs optimum. it probably matters more for a NA engine as you need all the help you can get