This'll scare the neighbours ....

You is such a botch

Progress this weekend

The main lump is built with flowed heads and re-profiled cams

Looking Pretty !!!

good progress Lee, considering it was just a pile of bits on Thursday!

I did have a YTS to help

the old doom blue bottom end

No ......just the bottom plate ...It was the best one about .
The main block is this ....It had the casting area for cross bolt but no holes so I had it machined .

Lee, so what exactly do these famous cross bolts do and how many are there.
I am guessing there are 2 and they just go through the middle of the block, between the cylinders???

There are four,two per side and they screw into the two central bearing caps.
We drilled and spotted onto the caps then tapped them .

This strengthens the block by clamping it in the middle .It's a rigidity thing .
It's a modification to the casting so presumably some issues surfaced .
It is not listed in the parts manual but was introduced around 89/90 I think .I would expect the 610 blocks to all be this variety .


Just looking at that pic afresh you can see how the two end caps show staining from the contact with the block where the two in the middle show none at all so there is a gap which would flex ??
The darkest one ,left, is at the fly end .

All the later 3ltr blocks (not the 2.9 odd fire engines) have this feature, and it was known the cap in position 3 was hardest pressed in terms of the frictional forces holding it in place. You can find the detail in the old engine analysis document (pdf) on the site. It refers the odd fire, however, it was known as a critical aspect back then. Note the 2.5 turbo crank is significantly heavier than the odd fire, and worse still for the 3ltr that simply make this situation worse as perfect balance is not possible in this configuration.

If you look at the parting faces of the block & cap, you nearly always see fretting between the two on non-cross bolt blocks as the cap, especially no. 3 is walking about in it's register due to the rotating vector loads. The above pdf also gives the locus of these forces, good reading.

Moral of the story, if you want a good bottom end to build a serious motor, you need the cross bolt block

Is that a new fly wheel in the back ground or the old one skimmed?

If you are thinking of getting a flywheel made, let me know as I would like to be part of a group buy.

Lightened and skimmed old one .

It was an old one remachined, and lightened considerably. Likely it's going to need a paddle clutch as I don't think we will get an organic plate to hold, even the larger diameter 24V / A610 variety. Looked at uprated pressure plates, probably be marginal at best but we shall see

You can considerably lighten the old one so why buy a special? Last time I had a special made up from EN8 cost 300 quid, so not really cheap and worth while I think for the costs involved. I had no choice for the application at the time