Author Topic: valve interference (Read 2115 times)

bbarnumboy · « **on:** April 21, 2009, 10:40:26 PM »

i am currently replacing my head gasket again.

the head was resurfaced the first time and i am getting it decked again since there is still room.

i was wondering after cutting the head twice plus the new cometic .030 head gasket, if i may have valve clearance issues with the pistons?

the valves on the head are not to the point where they protrude pas the head surface yet, but may be cloase after the resurfacing. let me know your thoughts guys.

bbarnumboy · « **Reply #1 on:** April 25, 2009, 06:36:07 PM »

actually i got a .040 thick gasket, with a set of cams will this cause the valves to hit? anyone? what thickness is the stock head gasket?

nicknikolovski · « **Reply #2 on:** April 26, 2009, 01:53:34 AM »

1.74mm - standard, next size is 2.04mm (+0.3). Bentley manual says the most material that can be taken off the head is 0.3mm and you need to use the 2.04mm gasket. Any more than this changes the size of the combustion chamber and will affect engine performance and running greatly. Also there is a minimum height specification for the head. The minimum is 139.55mm (from valve cover surface to bottom of head surface).

Hope this info helps. Ask the machining shop how much material was taken off. Remember any greater than 0.3mm and you should consider getting another cyl head.

bbarnumboy · « **Reply #3 on:** April 26, 2009, 12:23:34 PM »

well i am getting a new head now that mine is cracked but the gasket i bought it .040 so i was thinking with the higher lift from the set of cams i bought and the thin gasket, that it may contact the pistons. m thanks for the measurements. i wonder why they say it will effect performance much. it should be better with higher compression

B318M42W · « **Reply #4 on:** April 26, 2009, 05:03:21 PM »

until it starts to autoignite from all the heat from the compression...