PRODUCT DETAILS
Cometic 87mm K20/K24 MLS Head Gasket - Part #C4311-036 / -040 / -045
87mm is where most K-series builds live: every K24 at stock bore, and every K20 that's been taken out a millimeter. Cometic's C4311 is the 3-layer MLS gasket for that bore, sold here in .036, .040 and .045 compressed so you can put compression and valve clearance where the build needs them.
What It Is and Why It Works
Cometic's MLS gasket is three layers of stainless steel: two embossed outer layers coated in a Viton fluoroelastomer that seals against the block and head, and a center shim that sets the compressed thickness. The Viton handles 250 C, the stainless springs back after every heat cycle instead of taking a set, and the layered design tolerates the slight movement between an aluminum head and block that kills a composite gasket. It's the same construction Honda uses from the factory, done with more clamp margin.
Thickness is how you set compression and piston-to-valve clearance after a deck cut or a piston change. Thicker gasket, lower static compression, more clearance; thinner, the reverse. Cometic sells the same gasket in several thicknesses for that reason, and the bore has to clear your actual cylinder bore, not the one the engine left the factory with.
Specs
| Part number | C4311-036, C4311-040, C4311-045 |
| Material | MLS, 3-layer stainless with Viton coating |
| Bore | 87mm |
| Compressed thickness | .036 in, .040 in, .045 in |
| Engines | K24A1, K24A2, K24A4, K24A8, K24Z1 (stock bore); K20 bored to 87mm |
| Included | 1 head gasket |
Fitment
| Vehicle | Engine |
| 2002-2006 Acura RSX Base, Type-S | K20A3, K20A2, K20Z1 (bored) |
| 2002-2005 Honda Civic Si | K20A3 (bored) |
| 2004-2008 Acura TSX | K24A2 |
| 2003-2007 Honda Accord 2.4 | K24A4, K24A8 |
| 2002-2009 Honda CR-V | K24A1, K24Z1 |
| 2003-2011 Honda Element | K24A4, K24A8, K24Z1 |
| K-swaps | K24A at stock 87mm bore, or K20 bored to match |
87mm is the stock K24 bore and the common first overbore on a K20. Confirm the bore before ordering; a stock K20 is 86mm and takes C4300.
What to Know Before You Buy
Surface finish matters more than anything else. Cometic wants the block and head decked to 50 RA or smoother; an MLS gasket on a rough or corroded deck will weep coolant no matter how it's torqued. Have the head checked for flatness and skimmed if it's been overheated.
On a K24 head on a K20 block, or a K24 with a decked block and new pistons, this thickness range is what sets your final static compression. Run the numbers with your piston maker before you pick. .036 is close to stock; .045 pulls compression down noticeably and adds valve clearance.
Measure the bore. A K20 honed at 86 does not take this gasket; a K24 bored to 88 needs the C4312.
| Vehicle | Engine |
| 2002-2006 Acura RSX Base, Type-S | K20A3, K20A2, K20Z1 (bored) |
| 2002-2005 Honda Civic Si | K20A3 (bored) |
| 2004-2008 Acura TSX | K24A2 |
| 2003-2007 Honda Accord 2.4 | K24A4, K24A8 |
| 2002-2009 Honda CR-V | K24A1, K24Z1 |
| 2003-2011 Honda Element | K24A4, K24A8, K24Z1 |
| K-swaps | K24A at stock 87mm bore, or K20 bored to match |
87mm is the stock K24 bore and the common first overbore on a K20. Confirm the bore before ordering; a stock K20 is 86mm and takes C4300.
| Part number | C4311-036, C4311-040, C4311-045 |
| Material | MLS, 3-layer stainless with Viton coating |
| Bore | 87mm |
| Compressed thickness | .036 in, .040 in, .045 in |
| Engines | K24A1, K24A2, K24A4, K24A8, K24Z1 (stock bore); K20 bored to 87mm |
| Included | 1 head gasket |
| Packaged size / weight | 17.7 x 8.2 x 0.01 in, 0.7 lb (per PIM) |