A7 block

[Tiger]

Further to my quest to find a block.
Are +0.050” pistons available ?
Regards
            Tim

[Zetomagneto]

Further to my quest to find a block.
Are +0.050” pistons available ?
Regards
            Tim

Hello Tim, no 0.050 pistons available, nearest would be 57.25 mm .
Your question might suggest you have a block at 0.040”?
If so you could bore to 57mm assuming it would clean up at that.

Metric size pistons available from Tony Betts 56, 57,57.25, 57.5, and 58mm
so well catered for.

Imperial sizes available from other cherished supplier in 10,20,30,40,60,and 80. No plus 50 or 70.

[Tiger]

Thanks Zeto
Would you be kind enough to check this for me !
To fit a +0.050” os bore
Standard size 2.2”
Plus re bore 0.050”
Bore size in mm. 2.250 x 25.4 =57.15
Using 57mm piston
Gap 0.15mm
Gap 0.006”
Is this too big or am I missing something
Regards
Tim

[Zetomagneto]

Thanks Zeto
Would you be kind enough to check this for me !
To fit a +0.050” os bore
Standard size 2.2”
Plus re bore 0.050”
Bore size in mm.  2.250 x 25.4 =57.15
Using 57mm piston
Gap 0.15mm
Gap 0.006”
Is this too big or am I missing something
Regards
          Tim

Tim, as you have already calculated your bore is .006" too big to use 57 mm Pistons .
Are you sure the bore is .050 oversize, seems an odd size

[Tony Betts]

Hi tim,

Seven workshop has a close copy to Austins standard or 4 ring RS PISTONS.

Sizes standard at 2.2inch 2.210. 2.220. 2.230 2.240. 2.260 and 2.280.
But do check with them that thay have all sizes in stock befor you bore the block.

Stockist will run short of some sizes before they restock on all sizes.

Here at 7 county Austins. We stock the slipper Pistons that were developed from Austins sports profile Pistons. These are what people call slipper Pistons. They are a metric piston and ring.

Here's a conversion chart,

56mm = 2.20472
56.5mm = 2.22409
57mm = 2.24409
57.25mm = 2.25393
57.5mm = 2.26378
58.mm = 2.28346

Hope this helps Tony.

[Chris KC]

I just noticed Tony Leslie at Holmesdale Sevens lists +0.050 'competition' pistons in his catalogue - a call would confirm it.