franky
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| posted on 6/5/12 at 10:25 PM |
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Any head experts? Look at mine please!?
A quick story....
I decided to use my L24, it ran well with no knocks but always had a little bit of white smoke even when warm, compression results were all good but
I knew something wasn't right.
I pulled the head off and found this.
Looks like a slight leak on between the coolant and bore:unsure: Gasket told the story when looking underneath.
Upon close inspection I found on one cylinder cracks/splinters around the spark plug, No worries I thought, I could grind them back so there's
no sharp edges/stress points for cracks to start from. Would we agree this is a fair point? I understand that i'd increase the size of the
chamber slightly which i'd try to duplicate on the others, good or bad?
Next I cut back, hardly removing any meat at all. Once given a wipe over I noticed that the chamber on this pot has been altered...
An unmodified chamber
1: the spark plug hole/mount has been cut back
2: the shape isn't the same as others
3: I can feel that the shape isn't smooth and without machine marks the others have.
Is is the e31 head off my 1970 240. I'd like to keep/use it however I'm prepared to listen to some wise suggestions. Subject to pressure
testing is it ok to go ahead and use it? I can't work out the effects of having a chamber 1 or 2cc larger compared to others.
Strange thing is that the rest of the head is untouched, its not had any 'porting' or anything I can see done.
I'm also not sure if detonation has been the cause of the problems. Valve sizes are 33/42mm.... I take it that these are the standard size?
My plan was to have have hardened seats fitted, new valves/stem seals build engine with;
10.5:1 - 11.0:1 compression ratio
Piper 285 grind cam
dynamic balance on the crank with ATI harmonic damper
+50 bore with new pistons+rings
triple 40's
nice exhaust
4lb off the fly wheel.
full rebuild, obviously not making new history for 240z engines but a nicely thought out fun engine.
It did involve this head, I'd like it too still if possible.
Failing that has anyone got a e31 head knocking around?
:unsure:
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MikeRJ
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| posted on 7/5/12 at 09:42 AM |
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I wonder if that cylinder has suffered from damage (e.g. dropped valve, foreign object) in the past and has been repaired by welding, but not
machined/ground back to the correct shape? If you are going to the trouble having new seats fitted it would be worth having the chamber volumes
measured and balanced if required.
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ashg
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| posted on 7/5/12 at 01:49 PM |
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personally unless it was a really rare head i wouldn't bother, I would just go out and find another one.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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franky
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| posted on 7/5/12 at 02:30 PM |
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quote:
Originally posted by ashg
personally unless it was a really rare head i wouldn't bother, I would just go out and find another one.
Thats the rub, it is a rare head I think i've found another though but it'll have to wait due to cash flow issues
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clairetoo
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| posted on 7/5/12 at 02:34 PM |
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I'd worry about having exposed threads on the spark plug - how about , if you cut them all back to a similar shape , using either shorter reach
plugs or spacers on the plugs ? That original shape , to me , looks less than ideal anyway , with `pockets' either side of the plug ?
Its cuz I is blond , innit
Claire xx
Will weld for food......
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