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Minimatic Head
https://www.ausmini.com/forums/viewtopic.php?f=2&t=47743		 Page 1 of 1
Author:  niceboy1275 [ Thu Nov 20, 2008 10:31 am ]
Post subject:  Minimatic Head
Hi guys, my minimatic that I'm restoring, the current engine in it doesn't smoke or anything, but it does leak ALOT of oil. So thanks to ausmini I got hold of another minimatic 998 engine and box minus the head. I've managed to source some old literature regarding the auto boxes (thanks again to a very nice man off this forum, god I love ausmini) and once I've got the matic painted and on the road want to rebuild the spare engine and box and do a swap over. Does anyone know what sort of head the matics had on them? All i know was that they were a double spring or something.
Cheers!
Author:  Hanra [ Thu Nov 20, 2008 12:20 pm ]
Post subject:  Re: Minimatic Head
niceboy1275 wrote:
All i know was that they were a double spring or something.


I doubt it... I would of guessed its just a run of the mill 998cc head?
Author:  Timbo [ Thu Nov 20, 2008 12:34 pm ]
Post subject: 
I thought they had 12g295 heads? My 295 head came off an automatic Morris 1100.

Tim
Author:  simon k [ Thu Nov 20, 2008 12:49 pm ]
Post subject: 
I seem to recall a thread recently saying that Mini autos had the same head as a manual, but 1100 autos got the 295 head...
Author:  Matt68 [ Thu Nov 20, 2008 12:50 pm ]
Post subject: 
Yep, they used the 12G295 head from the 998 cooper, double valve springs and all. To make up for the power the auto took away.

Any small bore head will fit though :wink:
Author:  Hanra [ Thu Nov 20, 2008 12:56 pm ]
Post subject: 
Matt68 wrote:
Yep, they used the 12G295 head from the 998 cooper, double valve springs and all. To make up for the power the auto took away.


Thats really surprising. Its not like its actually going to require them...
Author:  Morris 1100 [ Thu Nov 20, 2008 3:58 pm ]
Post subject: 
I only really know about the Morris 1100 and Morris 1100 Autos. (but I will add the Mini 998 figures in brackets)

Horsepower
Manual = 50hp (Mini Deluxe = 40hp)
Auto = 56hp (Matic = 42hp)

Torque
Manual = 60lbs.ft. @ 2500rpm (Deluxe = 52lbs.ft 2700rpm)
Auto = 61lbs.ft. @ 2000rpm (Matic = 52lbs.ft 2700rpm (I am not certain about this figure :? ))

Compression ratio
Manual = 8.5:1 (Deluxe = 8.3:1)
Auto = 8.9:1 (Matic = 9.0:1)

They didn't need the double valve springs but that head was ready to drop on and gave the required amount of improvement needed.
Author:  drmini in aust [ Thu Nov 20, 2008 6:32 pm ]
Post subject: 
The 998 Matic did NOT get the 295 head. It got a stock 12A1456 head, with higher comp pistons. C/R was 9.0:1.
And, it got an HS4 carb (as all automatics did).
My 1970 998 Matic (with original head) had a 12A1456 on it.

I have several workshop manuals that cover the 998 Matic, all state the intake valves are 1.090" diameter (stocko 998 size, not Cooper).

The 1098 Morris 1100 automatic DID get the 295 head, and flat top pistons..
Author:  niceboy1275 [ Thu Nov 20, 2008 6:43 pm ]
Post subject: 
hmm mixed bag! ok, thanks for your posts guys, at least that sheds a little light on the subject. I have a 12g202 head here, so for arguments sake, I could put that on it if i wasn't stressed about keeping it 100% original? Any thoughts or comments?
Author:  drmini in aust [ Thu Nov 20, 2008 6:48 pm ]
Post subject: 
niceboy1275 wrote:
hmm mixed bag! ok, thanks for your posts guys, at least that sheds a little light on the subject. I have a 12g202 head here, so for arguments sake, I could put that on it if i wasn't stressed about keeping it 100% original? Any thoughts or comments?

Yeah throw that on it's worth a few HP. Looks the same outside anyway.8)
I put one on mine when the original head cracked (was a faulty casting).
Deck the 202 head about .050" or your C/R will be lower.
Original head thickness was 2.750", measure yours and check.
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