Author Topic: just had a spare head cut the mesurment is now 83.69 can I still use it??  (Read 3699 times)

erickmarciano

  • Associate Member
  • Gold
  • *****
  • Canada, Quebec, montreal
  • Posts: 545
Hi
just had a spare head cut the mesurment is now 83.69 can I still use it??it is a late 280 head.
Thanks
1994 E500 W124
1971 280sl
1989 Porsche 930 coupe
1988 e30 m3
2001 ducati mh900
2006 ps1000
1962 Vespa GS160

ja17

  • Full Member
  • Platinum
  • ******
  • USA, OH, Blacklick
  • Posts: 7414
Hello Erick,

The minimum height of a reconditioned cyl head is 84.00 mm (page 119 Technical Data Booklet 1972).  It is not in specs if your measurement are correct. It may be usable but can cause a lot of issues with compression, valve adjustments, valve clearances, cam shaft alignment etc, in other words a risk at best.

Double check you measurements.  Measure at the ends and center of the head. Make sure your measuring tool is accurate and you are using it correctly.

I never have my heads cut unless absolutly necessary.  There is just not much to spare before you have a boat anchor on your hands.
« Last Edit: December 01, 2009, 01:17:35 by ja17 »
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

Shvegel

  • Inactive
  • Platinum
  • ******
  • USA, OH, Cleveland Heights
  • Posts: 2978
I'm with Joe here. I had a valve guide come loose in the head and needed to pull it off and have it reconditioned. I brought it to a machinist I trust(700 miles from my home) and told him to just do the valve work(new valves guides etc) He asked if he should cut the deck and I told him no. He then asked if he could measure it and I told him  "It sealed when it came off and the cam turns well. The way I have it tuned it just starts to ping on a hot day with 94 octane fuel in it...just leave it alone."

OK so you are .31mm too short.  As Joe stated the cam timing will be retarded slightly, The valves will be .31mm closer to the pistons at full lift and your compression will be higher than design due to the cumbustion chamber being .31mm too short.. All those things are slightly worrisome provided you have access to decent fuel. But what troubles me more is if this was an uncut or slightly cut head and they had to shave that much off to straighten it out what does the alignment of the camshaft bearing journals look like?  A good straight edge and some feeler gauges should tell the story.

I would consider using it if I had too but if there are better heads to be had it might be worth looking into them.