Centre Main Cap/Strap.
Due to the 3 bearing design of the A-Series, on high output engines the centre main bearing is put under heavy loads, In some cases the main cap can flex, this movement can cause the bearings to fail, possibly damaging the crank & or block. Adding extra support to the bearing cap is very worthwhile. There are two possibilities as shown below. The 2 bolt is the cheapest and easiest & should be ample for most applications, the 4 bolt is the more expensive and requires more work, but is the better item.
It is recommended that the main caps should be line bored after fitting the 2 bolt strap, as machining of the cap can distort it. It is ESSENTIAL when the 4 bolt item is fitted.

2 Bolt Centre Main Strap.
To fit a centre main strap is a simpler process than the 4 bolt cap as the existing main cap is used, but the top of it is ground flat. The strap then sits on top & is held in place by longer bolts. This gives extra support to the centre main. Torque setting is standard.

4 Bolt Main Cap.
To fit a 4 bolt centre main cap the block will need to be drilled to accomodate the two extra allen bolts. The cap will then need to be "line bored" to make sure it is perfectly in line with the other main caps. The centre two bolts are torqued to the standard setting of 67ft/lb & the allen bolts are torqued to 50ft/lb.

Undercrown Oil Cooling.
Click here to see more info.

Dry decking involves blocking the waterways in both the head & block face. This means in the event of a gasket failure no water will get into the cylinders. Obviously this is of benefit on a race car as this will allow you to finish the race & avoid a DNF.
There are also cooling benefits as it promotes better water flow around cylinder 4.
If a true dry deck is to be achieved both the head & block waterways must be plugged.
For a road car I prefer to know if the gasket has failed & am only interested in
the cooling benefit, so I only blocked the waterways in the block, which can be done easily by tapping & blocking with grub screws. Creating a semi dry deck.

I run this semi dry deck system & it seems to provide a much more consistent & even temperature.

The end of the head is modified to allow fitment of one of the adaptors shown below. The other adaptor is fitted into the block after one of the core plugs has been removed. The hose allows passage of the water through the block & accross the head promoting more even coolant flow.

Dry deck adaptor kit.