Need Help Measuring a Type 4 Case / Mains

[Patrick1984]

Hi All,

I'm waiting on my heads and barrels to be machined and have stripped my case, got it all cleaned up nice and put it back together then torqued the main cap nuts and setup a bore gauge to measure the main bearings. Issue I'm having is I can't get a consistent reading on them. I did the light check from the back on the centre main and if you're really fussy you can see a small dot of a shimmer. What I don't make sense of is they seem very out of round in an inconsistent way and worse on the outer ones. I think the case is misaligned and the crank / bearings play a role in aligning it. Should i have the cam and bearings in at this point to help on that side? At the moment I can feel a light ridge between the case halves at the bearings with my nail and it measures similar to if you have a rod cap on the wrong way around. With a gauge in some points its spot on but some are up to .10mm over and some points seem under size. Centre bearing measures the best which I thought from what I 've read was the one to watch for.

I'm not expecting the case to be too bad as its had a rebuild at some point and the bearings were in good shape. Crank measures up stock and the bearing were std/std also.

Can someone who has done this a few times give me a rundown of how you measure the mains or point me to a thread that covers it? I couldn't find one when using the search.

If you want anymore info let me know.

Thanks,
Patrick

[twodollardoug]

I'm watching this with interest.

[Patrick1984]

Thanks Doug, I'm guessing I need to split it again then pull it all together nice and slow with the cam in but curious what the best way is before I pull whats left of my hair out.

[Eddie010]

I use this one to measure the case, hope this is what you mean.
They have different sizes
https://www.csp-shop.com/en/tools/engin ... 0122a.html
They also have them for cranks.

[Patrick1984]

Can't say I've seen those before but I like the idea. I guess if it's been you just slip a feeler gauge in. I'm measuring using a dial bore gauge. What you posted makes me think I could put a straight edge across it when split and measure the depth of each half but this will only measure the centre. I like to measure right around and edge to edge with these things. Haven't gone the plastigauge road yet either. Could do that with the old bearings to get an idea I guess

[Bruce.m]

I’d suggest splitting the case and carefully check for any burrs or raised edges. Knock back any high spots with a machinist’s stone. If you gently stone off the case face you will shiny marks around bolt holes and any edges that have been knocked.
Then clean and retorque using the correct pattern.

[Clatter]

Here's a thread i put together for a beetle motor a while back.. has some tricks..
https://www.thesamba.com/vw/forum/viewt ... p?t=692654
There's also some info in the build in my sig line below.

That said, you'll want to spend plenty of time trying to get measurements any way you can and as best you can.
Try your measurements at the different 'points on the clock' and see how round the main saddles are.
just because it hasn't been line-bored doesn't mean it isn't due for one.


Also check to make sure you have a matched case.
Somehow, what you describe sounds like a pair of mis-matched cases from different motors.
They have numbers stamped in, usually near the top rear.
See if you can't find those and make sure they match.
Post some pics here of the numbers and of your main saddles.

It's tricky to use a bore gauge correctly.
They make them in different accuracy levels as well.
Takes practice to get good at, years to get really good..
if you can't tie a knot, tie a lot..

[Patrick1984]

Thanks Bruce and Clatter. Guess I need to go get my hands dirty again. Stone idea makes sense. I've done similar things with other motors when head gaskets fail to see if its all flat.
Case numbers match


For the saddles see below.
















I'm using a cheap bore gauge but can get my hands on an expensive one if need be. I put the micrometer in a vice and set it to 69.95 and 70.05 to see how the gauge would go and it was spot on either side of 70. I'll split it again and measure the depth of each half using the dowel pin trick from Clatters 1776 thread and then check its all flat and try again.
Cheers,
Patrick

[dstar5000]

Send it for an align bore and be done with it. If you're using a cheap bore gauge you're wasting your time.
Don

[Patrick1984]

Well Don wins. I borrowed a real gauge and its all spot on. Centre main is perfect and 1 and 3 are 70.02 at their worst. Little taper across them but over all in good shape. Thanks for the input.
Cheers,
Patrick