Deep trough in fire ring with blackened gutter path into water way.
 Large particle entrapment on assembly.
As per previous feature "Dirty Assembly". In this example the dirt particle was extremely large promoting the gutter path to form very quickly. Gutter paths can similarly develop if block or head facings have localised low spots. Lack of fire ring clamp at a low spot will allow high pressure / high temperature gases to enter the gasket composite backing material and burn back will quickly occur.
Ensure cleanliness of assembly. As a minimal precaution have the head refaced and if practical reface block also. Checking a cylinder head / block face with a straight edge is not an effective method of proving flatness.

 Two or more stud / bolt holes pulled and gauled.
 Poor location of gasket or movement of same during assembly.
If an engine has head locating dowels then this problem will not occur. However, always ensure that dowels are in good condition and correctly located. Many engines rely on the head bolts studs to locate both the gasket and the head. In this case we recommend the following:
Heads which are located by studs can present problems particularly if "spring" exists when assembled to block. Sliding the head gasket over the studs sometimes creates tight assembly and head gasket distortion and hole gauling can occur. Where practical it pays to place the head gasket on the block and screw the studs in through the gasket into the block. A light smear of grease on the assembled studs will help the head slide precisely down into position.
If possible it is advisable to make up and employ two diagonally opposed studs in which to guide the head down onto the head gasket. Lightly screw in the remaining head bolts before finally replacing the studs. This is particularly easy if replacing stretch bolts as you simply cut the heads off two old bolts & hacksaw in screwdriver slots for ease of removal. This method is essential when fitting the cylinder head on a Rover "K" Series engine. Any side manouvering of these heads can cut 8 seriously impair the silicone beading on the head gasket.