where can we get these main caps??

[gedu]

Agree with Jamo, when changing main bearing caps, you must make all humanly possible attempts to keep crank line straight. Easiest way to accomplish it is by line boring.

There is a reason main bearing caps don't have sparepart number

[martinjs]

Looking at Mark h's gallery, it looks like he used the OEM caps with washers to mount the girdle onto, i cant see a problem doing it that way.

[Flat on my back]

.

Using the oem main caps and a supporting 'shoulder' to the girdle means each 'shoulder' is machined for each position, a time consuming and delicate job.

Requires a precise measurement for each position to be made and the 'shoulder' ground to fit.

Not 'washers' at all...

[Mark Halligan]

Using the oem main caps and a supporting 'shoulder' to the girdle means each 'shoulder' is machined for each position, a time consuming and delicate job.

Requires a precise measurement for each position to be made and the 'shoulder' ground to fit.

Not 'washers' at all...

You are right, doing mine was a very time consuming job with each spacer being individual to each position on the mains caps.

I like the idea of using those caps in the first post, but these would also need to be a very precise fit with regard to their heights relative to the 'pan rail'.

I am not sure how Roger (Audi_CQ) or Aelred set their girdles up, but after a lot of research I decided to set mine with a 0.005" preload (gap) between the girdle plate and the pan rail (bottom face of the block).

Those mains caps would still very likely require extra machining (after align boring) to get them all at the 'same height' relative to the block, and if they come up lower than the pan rail height, even by a few thou, they would still need spacers between them and the girdle plate.

I agree that those caps are a better looking solution to using spacers but they will still take a lot of work to get right.

By the way most good machine shops will be able to align bore/hone a block, I had mine done at Gosnay's in Essex.

[martinjs]

Using the oem main caps and a supporting 'shoulder' to the girdle means each 'shoulder' is machined for each position, a time consuming and delicate job.

Requires a precise measurement for each position to be made and the 'shoulder' ground to fit.

Not 'washers' at all...

Yes i do realise that already, but IMO its easier/cheaper than line boring.

[Flat on my back]

.

Going by the piccy in post 6 the weakest point in the main cap is the 'bridge', not the outer bolt holes or bolts...i'm no mechanical engineer though.

The strongest solution would appear to be the machined caps...yes expensive to get right but so is a broken engine.

Still trying to fully understand the theory of the girdle...seen them being used on alloy blocks but that's understandable.

ATM i have no idea when these extras are needed, eg. at what power level.

[Fat Audi 80]

Overkill in fitting the caps or boring? It's not if you change the cap it must be inline bored to ensure the crank is running true

Sorry, I should have been more unambiguous. I meant, the new bearing caps look to me to be overkill unless you are going for stupid horsepower. We have seen the standard bottom end setup perfectly good for high power levels.

I will go back to the detailing forum now....

[Audi_CQ]

Yes i do realise that already, but IMO its easier/cheaper than line boring.

You should linebore it anyway just to be sure it's 100%. No reason to be "cheap" when rebuilding/tuning an engine