Jump to content


Photo
- - - - -

850 Block


Best Answer DeadSquare , 02 September 2019 - 07:23 PM

The center Main Web is "meatier" to accommodate the larger thrust washers, and there may be other differences.

Go to the full post


  • Please log in to reply
10 replies to this topic

#1 whistler

whistler

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 980 posts
  • Location: Cardiff

Posted 02 September 2019 - 04:34 PM

I have a mk1 850 block with 12A450 casting number on the rear.

 

I read somewhere that BMC used the same block for the 998 or 1100 but different machining on them. 

 

My friend google hasn't been any help in this matter so I'm looking at the experts for some sort of answer.

 

Anyone know the answer?



#2 DeadSquare

DeadSquare

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,583 posts
  • Location: Herefordshire
  • Local Club: Herefordshire Motor Club

Posted 02 September 2019 - 04:47 PM

You read correctly.  The block that BMC used for the 998 is the same block that they used for the 1098.



#3 whistler

whistler

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 980 posts
  • Location: Cardiff

Posted 02 September 2019 - 05:51 PM

You read correctly.  The block that BMC used for the 998 is the same block that they used for the 1098.

Was the 850 block the same casting but different machining?



#4 DeadSquare

DeadSquare

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,583 posts
  • Location: Herefordshire
  • Local Club: Herefordshire Motor Club

Posted 02 September 2019 - 06:25 PM

 

You read correctly.  The block that BMC used for the 998 is the same block that they used for the 1098.

Was the 850 block the same casting but different machining?

 

 

No.



#5 DeadSquare

DeadSquare

    Camshaft & Stage Two Head

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,583 posts
  • Location: Herefordshire
  • Local Club: Herefordshire Motor Club

Posted 02 September 2019 - 07:23 PM   Best Answer

The center Main Web is "meatier" to accommodate the larger thrust washers, and there may be other differences.



#6 whistler

whistler

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 980 posts
  • Location: Cardiff

Posted 03 September 2019 - 09:02 AM

The center Main Web is "meatier" to accommodate the larger thrust washers, and there may be other differences.

Thanks. Hadn't thought of that. The 850 ones are miniscule.



#7 ACDodd

ACDodd

    Up Into Fourth

  • Mini Docs
  • PipPipPipPipPipPipPipPipPip
  • 2,216 posts

Posted 03 September 2019 - 11:08 AM

The 850 has wider main bearing tunnels. As a result the 998 and 1098 cranks won't fit without significant machining to the crank. The 850 blocks do not have sufficient clearance to swing the 1098 crank without suitable mods. The bearing caps are skinnier. The 850 block is not the same as the 998 or 1098 block in the ones I have worked on.

Ac

Edited by ACDodd, 03 September 2019 - 11:11 AM.


#8 whistler

whistler

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 980 posts
  • Location: Cardiff

Posted 03 September 2019 - 02:50 PM

The 850 has wider main bearing tunnels. As a result the 998 and 1098 cranks won't fit without significant machining to the crank. The 850 blocks do not have sufficient clearance to swing the 1098 crank without suitable mods. The bearing caps are skinnier. The 850 block is not the same as the 998 or 1098 block in the ones I have worked on.

Ac

Thanks AC, the 850 stays as standard factory then. Just brought the block back from the machine shop where it's been acid dipped. Now to hone the bores.



#9 MiniMadRacer

MiniMadRacer

    Mini Mad

  • Members
  • PipPipPipPip
  • 152 posts
  • Location: Essex

Posted 03 September 2019 - 02:56 PM

Are you going to put some CAM bearings in it ?



#10 whistler

whistler

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 980 posts
  • Location: Cardiff

Posted 03 September 2019 - 04:27 PM

Are you going to put some CAM bearings in it ?

No. the front one is OK. Camshaft is fine, so It'll be going back together with new rings and bearings etc .



#11 johnv

johnv

    Mini Mad

  • Members
  • PipPipPipPip
  • 201 posts
  • Location: Surrey
  • Local Club: FDMC

Posted 03 September 2019 - 04:40 PM

I thought acid dipping ruined the cam bearings. That's what my machine shop said anyway




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares