Ausmini
It is currently Sat Jul 12, 2025 8:30 am

All times are UTC + 10 hours




Post new topic Reply to topic  [ 135 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8, 9  Next
Author Message
 Post subject:
PostPosted: Sat Aug 15, 2009 8:28 pm 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
drmini in aust wrote:
Super-mini wrote:
can we just overbore to 998 size pistons? and how many thou is that over std?

Overbore about .060" and you can fit stock 998 64.6mm pistons.
You will need to deck the block by about .156" though, as they are shorter pin to crown height.


Is any of that an issue?

Is there enough metal in the block for both operations?


895cc with a better bore/stroke ratio sounds interesting.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 12:21 pm 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
Looking at some specs, i notice that there's a 0.065 inch difference between 850 and 998.


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 2:12 pm 
Offline
religious status
religious status
User avatar

Joined: Fri Mar 19, 2004 6:19 pm
Posts: 39754
Location: near Baulkham Hills, NSW
Cush there is no problem with boring, back in the 60s I used to overbore 850s and stick a new 1098 crank, rods and pistons in em.

The major mod was to the 850 centre main cap and block, to allow the 1098 crank to fit (its bearings are narrower). Won't affect you with an 850 crank. :wink:

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 2:52 pm 
Offline
1360cc
1360cc
User avatar

Joined: Mon Jul 26, 2004 7:23 am
Posts: 7339
Location: Sunny Shine Coast, Qld Australia
cush wrote:
Wombat wrote:
I have a set of STD 998 pistons -NOS I could be encouraged to part with :wink:


'ow mooch?


Make an offer less than you would have to pay from Minispares with postage at a price you would be happy to pay as a 'fair' price.

_________________
David L
Image

My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 6:27 pm 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
drmini in aust wrote:
Cush there is no problem with boring, back in the 60s I used to overbore 850s and stick a new 1098 crank, rods and pistons in em.

The major mod was to the 850 centre main cap and block, to allow the 1098 crank to fit (its bearings are narrower). Won't affect you with an 850 crank. :wink:


Ohh. that's exciting...

SO what's the deal with overbore sizes..

SP64 Specs tell us that 998 is 2.543 in. does that mean the bore is 0.2543 and the piston is actually marginal smaller or is it the other way around?


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 6:35 pm 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
Wombat wrote:
cush wrote:
Wombat wrote:
I have a set of STD 998 pistons -NOS I could be encouraged to part with :wink:


'ow mooch?


Make an offer less than you would have to pay from Minispares with postage at a price you would be happy to pay as a 'fair' price.


That's a decent option, thanks.

I'll keep that in mind ;)


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 6:44 pm 
Offline
religious status
religious status
User avatar

Joined: Fri Mar 19, 2004 6:19 pm
Posts: 39754
Location: near Baulkham Hills, NSW
cush wrote:
drmini in aust wrote:
Cush there is no problem with boring, back in the 60s I used to overbore 850s and stick a new 1098 crank, rods and pistons in em.

The major mod was to the 850 centre main cap and block, to allow the 1098 crank to fit (its bearings are narrower). Won't affect you with an 850 crank. :wink:


Ohh. that's exciting...

SO what's the deal with overbore sizes..

SP64 Specs tell us that 998 is 2.543 in. does that mean the bore is 0.2543 and the piston is actually marginal smaller or is it the other way around?

2.543" is the actual bore size. Piston is a couple of thou less. :wink:
But best to not bore it until pistons are available to hand...

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 8:29 pm 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
Whilst i think i know the answer..

I've got a good 998 block here with (surprise surprise) 998 std pistons, I could just use those, yeah?

The bores look look fine and i trust the previous owners opinion that all the block needs would be a re-ring (and i know you don't believe in that. ;) )

I trust his opinion, because the PO was 50% of the duo that killed the mini 1000 series way back when... :P


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 9:56 pm 
Offline
Yay For Hay!
User avatar

Joined: Wed Sep 08, 2004 9:27 pm
Posts: 15912
Location: Wodonga - Vic/NSW border
cush wrote:
Whilst i think i know the answer..

I've got a good 998 block here with (surprise surprise) 998 std pistons, I could just use those, yeah?


don't use old pistons - new ones are too cheap

_________________
did I tell you that I won a trophy?


Top
 Profile  
 
 Post subject:
PostPosted: Sun Aug 16, 2009 10:00 pm 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
even 998 stockies?


Top
 Profile  
 
 Post subject:
PostPosted: Mon Aug 17, 2009 9:16 am 
Offline
1360cc
1360cc
User avatar

Joined: Mon Jul 26, 2004 7:23 am
Posts: 7339
Location: Sunny Shine Coast, Qld Australia
cush wrote:
even 998 stockies?


Yeh you need new standard stockies :wink:

_________________
David L
Image

My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!


Top
 Profile  
 
 Post subject:
PostPosted: Mon Aug 17, 2009 9:37 am 
Offline
THIS SPACE FOR RENT
User avatar

Joined: Wed Jun 09, 2004 3:35 pm
Posts: 11847
Are 998 stockies actually available new?

Edit... yep.. 170 from the Kraft


Top
 Profile  
 
 Post subject:
PostPosted: Mon Aug 17, 2009 5:12 pm 
Offline
1360cc
1360cc
User avatar

Joined: Mon Jul 26, 2004 7:23 am
Posts: 7339
Location: Sunny Shine Coast, Qld Australia
Wombat wrote:
I have a set of STD 998 pistons -NOS I could be encouraged to part with :wink:


:roll:

_________________
David L
Image

My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!


Top
 Profile  
 
 Post subject:
PostPosted: Tue Aug 18, 2009 1:30 am 
Offline
1098cc
1098cc

Joined: Mon Feb 12, 2007 2:40 pm
Posts: 1325
Location: wasleys S.A.
Cush, If you want .020" and .040" oversized 850 pistons and rings then try your nearest Autopro shop.
The bloke I deal with at autopro in gawler can get a new set of pistons and rings for around $200
If you are building a stock eng then JP pistons also sell 850 pistons.
If you want 998 pistons Autopro can get them as well. There are some pistons available that have a pressed in gudeon pin instead of those nasty circlips and floating pins. The rod needs to be reamed out about .003" . The pistons have a cutaway skirt where the gudeon pin is but only have 3 rings.

_________________
Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com


Top
 Profile  
 
 Post subject:
PostPosted: Tue Aug 18, 2009 7:13 am 
Offline
religious status
religious status
User avatar

Joined: Fri Mar 19, 2004 6:19 pm
Posts: 39754
Location: near Baulkham Hills, NSW
Don't forget 850s here had that `clamp bolt' little end in the rod. You would need to grind a notch in the gudgeon pins to fit 998 pistons (IMO not a great idea) or fit 998/1098 rods. Same length etc and fit fine.:wink:

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 135 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8, 9  Next

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  

© 2016 Ausmini. All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.