Club 80-90 Forums

So...while I had covid the front cam bearing was line bored back to size, at no small expense. Perfect timing for once! It looks good so now to see if its worked out and I can finally get this thing assembled.

Well that was rather more involved than I was expecting, but now the cam runs nicely.
Basically, more than one fault in play. Again.
Put cam in one case half, spins freely, put on the other half and torqued it down, could only just turn the cam with a flat screwdriver...so that meant next to no running clearance. Dismantle, inspect bearings. Inspect cam journals. Scratched head, reach for micrometer. Bingo. The new cam had one slightly oversize journal (25.01 diameter at the gear end compared to 24.98 for the others i.e. thats the oil film clearance) so I had to polish it down with 1200 emery glued to a bit of 1/2" square nylon.
Half an hour and several strips of emery paper later, size acheived and the cam turns easily by hand
This is engine building, not just engine assembly.

Epic chap..

I'd have given it a good few brushes with a wood file.

This is now a meditative and zen engine build. It will be done when it decides it is ready, not when I want it.
Did a dry build, it still grabs the mains and goes tight. Reached for the new mic set, checked with the gauge, the mains are over top limit. Middle pair are 55.01 and not 54.98, must have been ground on a hot day or with a faulty mic
So now the new rods are scrap and the crank still needs to be polished down to get running clearance.
Can nobody do their job properly?

This has got to be so frustrating.

I think my head would have incurred a fair few glancing blows with the nearest brick wall.

It seems so close, but destined not to get any closer.

I am not so sure I could be so philosophical about it.
I would want to bang a few heads together.
These machining jobs are costly in both your money and your wasted time.

I suppose it is just a matter of hanging in there and hoping for a lucky break soon.

Local engine shop were not only very good in giving me next day service but also managed to grind the miniscule amount required off the main bearings successfully.
We are talking about the thickness of a kitkat foil wrapper off the diameter. No margin for error whatsoever.
Moving forward again.

I have lost count of the number of sets of conrods I have bought, cleaned, weighed, returned, fitted, found production faults etc etc but finally I have got a set of 6 that are within a 2.5g weight spread and with maximum variation of 1g, all without any balancing.
Individual 4cyl boxed sets are very closely matched but set to set can vary as much as 10g i.e. one set will have 645g nominal rod weight, another 655g.
Encouragingly the piston pins weigh +/- 0.1g which is amazing.

Finally. I have a thin green line.

plastigauge?

Its got a slight tight spot, the cam gear must be a thou or so eccentric however I can turn it by hand with two bolts in the end if the crank, so it can't be that bad.

It will bed in.

Or explode.

Fingers crossed, its not the latter.

Piston balancing, got them pretty close (overcooked one by 0.2g) then did the last bit by playing musical pins to get them +/- 0.1g
VW dont give anything much to work with but there is a boss that can be dressed off, the rest came off by chamfering the step inside the skirts.

Saving my thumbs these days.

Also: one pin was bigger than all the others! Only by 0.05mm or ao but thats the difference between "falls in" and "nnngggghh" aka too tight. Much polishing on the lathe with 600 and 1200 emery wrapped around a wide machine parallel put it right.

Getting somewhere now. Didn't have enough green top barrel seals in stock. Then had to go hunting for piston circlips...

Hopefully the green seals are just a temporary set-back.

I make a point of watching out for your posts in this thread.
Loving the attention to detail.
I have learnt bucket-loads reading this thread.
Lots of which had never occurred to me previously.

The more I read, the more obvious it is that I know very little. Many thanks for the brain training.
I hope I never need it, but if I do, I have more chance of getting it right.