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My warped head measured 17/1000”. The machine shop said they can resurface but I have read where the head becomes a good boat anchor if warped 7/1000” or more.
What is the go/no-go measurement before I invest money in this warped head? Also, provided being warped 17/1000 is still okay to resurface, should I run the OEM head gasket or the one that is 3/10mm thicker?
Thanks for your replies.
Think I just found my answer. Per Bentley, the minimum permissible deck height is 4.909. New it is 4.924 +/- 0.004. So that means between 0.011 to 0.019 can be milled with the 4.909 being the governing number.
Welcome your thoughts…
Yes, you had the right answer. Be careful about making it the head too thin tho. Just have them mill off enough to get it flat again. If the head is milled thinner then 4.915 start thinking about using clay to confirm that your valves don’t hit your pistons.
It’s one of those “trust but verify” situations. Sometimes things that “should have worked”…“don’t”.
Not knowing why your head warped, if overheated and blown head gasket, you may want to pressure test to make sure it did not crack at the cam journals.
If you have already done this disregard.
Our head warped at the June LeMons race on the Shenandoah circuit Summit Point due to a team error (running the thinner eta radiator, driver turned the fan off ??, team putting the car back on the track without fully diagnosing why the temp spiked, etc…). Same weekend as you guys on Summit’s main track. The car was running great, turned the second fastest lap of the day (field of 101 with 16 BMWs) then barf goes the cooling.
After consult with R&L Machine (they do all of Turner Eng’s work) and Ireland Eng, my local machine shop will proceed provided that 1) the camshaft is not binding, 2) can maintain the minimum permissible deck height of 4.909 and 3) the head passes the pressure test. It will make a nice boat anchor if failing any one of those three.
[quote=“Russell” post=73080]Our head warped at the June LeMons race on the Shenandoah circuit Summit Point due to a team error (running the thinner eta radiator, driver turned the fan off ??, team putting the car back on the track without fully diagnosing why the temp spiked, etc…). Same weekend as you guys on Summit’s main track. The car was running great, turned the second fastest lap of the day (field of 101 with 16 BMWs) then barf goes the cooling.
[/quote]
Hmm. I would have thought that a serviceable eta radiator would have been good enough, especially if the radiator was adequately shrouded so all air had to go thru the radiator.
Once the car is moving, the radiator fan should be turned off.
Our head expands more with heat then the block does. The HG accommodates this dissimilar expansion, but it won’t last forever. Eventually the HG fails. If the engine gets hot a lot, the HG will fail sooner.
There’s lots of ways for an engine to over-heat. Cap won’t hold pressure, coolant leak, unshrouded radiator and a hot race, inside of radiator gummed up, thermostat not opening all the way, water pump failure, etc.
Just closing the loop on this thread.
Given the cam and rocker shafts were not binding and the head passed the pressure test, we decked the head by removing 0.014" and still met the minimum permissible deck height 4.909". Reinstalled using a standard thickness head gasket. The car ran great at the LeMons race at NJMP - Thunderbolt circuit with temps never exceeding 180 for the ~ 14 hours of racing.