No you cannot swap main caps on smallbores either, for the same reasons.
They were line bored in situ with the block, in production.
Using another cap later is only possible if:
1. the horizontal alignment between `new' cap & block tunnel bore is very close (withins thou's)
2. material is removed from the cap and the bottom of the block, then the whole lot- block and 3 caps line bored again.
Expensive job...
For my last 1310 I made a strap from EN25 steel, and step machined it to fit the cap after the top of cap only was ground flat.
Current thinking (both GR and KC) is straps are not needed, as long as you don't change down at 8K+ and use the engine for braking....
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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.
