Head Thickness and Valve Clearance

[Steve S]

A question for those with engine building experience... On an otherwise stock engine, what is the maximum amount the head can be skimmed before the valves hit the block? Also how much would a +030 bore and 1mm larger EX valve affect this? - Steve Simmons, TC8975

[Bill Hyatt]

Steve,Trial & error  1. Cut a supply of disks in successive 1mm larger dia s & glue to top of OEM valve2.Find an otherwise expired head of OEM or close to OEM thickness, fit valve & measure wall clearance.3.Deck head in .010 increments while fitting successively 1mm larger disks to top of stock valve until there is 1.5 mm - 2.5 clearance between I & E. valve & cyl. wall. More if guides are worn!4. Double check that you still have adequate clearance between valve & piston top thru full rotation of crank. 1-2.5mm (I & E) if near stock N/A engine5.Be sure to note following if you pass results of research to Group.A. engine block deck heightB. Head gasket thicknessC. Valve lift/durationD. Rocker ratioE. Final Head deck heightF. Et al Optimum reasonable valve dia. can be mol determined by researching Lovell Effect . Whether or not resultant valve dia. can be achieved is another question resolved by #1-#4 test procedures.  -Bill HyattSent from my iPhone

On Jun 23, 2019, at 4:13 PM, Steve S mail@mgnuts.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:

  A question for those with engine building experience... On an otherwise stock engine, what is the maximum amount the head can be skimmed before the valves hit the block?  Also how much would a +030 bore and 1mm larger EX valve affect this? - Steve Simmons, TC8975