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Tell me about heads
https://www.ausmini.com/forums/viewtopic.php?f=5&t=53508		 Page 1 of 1
Author:  Dylans Clubby [ Fri May 22, 2009 10:20 pm ]
Post subject:  Tell me about heads
no jibber-jabber about tasmanians please :lol:

my 998 has been bored out 20 thou, it is tuned properly and goes well. i'm having issues with oil consumtion though, i'm under the impression that my valve guides/seals are worn (lots of bluye smoke on startup, phenomenal oil consumption). so i'd like to get my hands on another head, get it good to go, then whip the current one off and whip the new one straight on. get the job done in a day, so i'm not off the road for too long.

current head is, as far as i know, standard. what will a 12G202 do for me? does it need to be matched up with a different cam, etc? what will it do to the compression ratio? (which is currently high, but unsure of figure)

cheers all, D
Author:  drmini in aust [ Fri May 22, 2009 10:38 pm ]
Post subject: 
If you have high oil consumption I'd be giving it a compression test. Worn valve guides will give a bit of smoke on startup but much oil won't get down there to cause that.
Does it blow smoke under load? if so it's rings for sure.
Author:  Dylans Clubby [ Fri May 22, 2009 10:41 pm ]
Post subject: 
will ahve to get the tester on to it tomorrow, will give readings across all cylinders.

i'm not noticing smoke under load but eye-witness accounts tell me it smells strongly of oil smoke. i'm also getting a pretty dirty bootlid
Author:  henry the mini [ Sat May 23, 2009 9:34 am ]
Post subject: 
I have got a spare 998 head off the van here, looks like a good starting point. You can have it, along with the seat if you want!
Author:  Dylans Clubby [ Sat May 23, 2009 1:31 pm ]
Post subject: 
what head is it though? we've got a couple of spares here, so if the 202 isn't a big deal i'll probably just use one of those.

but as far as i can ascertain, the 202 will give the mini a noticable cracker up the tailpipe?
Author:  slinkey inc [ Sat May 23, 2009 3:53 pm ]
Post subject: 
I recently swapped heads for a worn valve guide (always keep a spare Cooper S head ready to go :wink: ) and found on my old old that an exhaust valve had actually raised up and was slightly dislodged...very dodgy.

Car ran alright, blew loads of smoke in idle and some on deceleration. It used bugger all though. More oil was lost from leaking than burning. Also made 82hp atws at a dyno day in that condition! :lol:

Anyways, this whole story has a singular point... It shouldn't use loads of oil if a valve guide is worn. But it will appear to blow a fair amount out the exhaust.

Goodluck with the repairs. :)
Author:  drmini in aust [ Sat May 23, 2009 4:40 pm ]
Post subject: 
Dylan's Clubby wrote:
what head is it though? we've got a couple of spares here, so if the 202 isn't a big deal i'll probably just use one of those.

but as far as i can ascertain, the 202 will give the mini a noticable cracker up the tailpipe?

A stock 202 head on a 998 is worth about 3 or 4HP, if you skim it .040" or so to keep the C/R reasonable (they have slightly bigger chambers). :wink:
I dropped one on my 998 MiniMatic and you could feel the difference.
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