dlknight

Back at the beginning of August I did my back in... spent a couple of hours in A+E on the seriously uncomfortable metal chairs to be sent away with some painkillers after a 5-minute consultation.

A few days later I was feeling a bit better after a couple of co-codamol tablets (but also a little sleepy), and thought I'd have a go at installing the rods and pistons in the block.

First mistake was not having the piston lined up properly in the ring compressor (slightly tilted) so I ended up borking the bottom oil ring and control ring. Luckily no other damage, so I will have to find out if I can order replacement oil rings from Mahle for one piston. After learning my lesson I was able to smoothly install the next piston into the bore.

NOTE: If you need any more than a gentle tap on the piston to push it into the bore then something is wrong, do not continue! (I blame the co-codamol!)

With the second piston successfully installed (in cylinder #4) I checked the rod bearing clearance (3 times), with plastigauge.

This was when I decided to stop as I was seeing quite a tight clearance which was confirmed by the previous measurements I'd made with the micrometer. The table below shows my measurements taken with a micrometer and telescopic bore gauge.



My clearances are within Porsche specification (0.034mm - 0.092mm) but outside of the recommendations from ACL - these give around 0.0020" or 0.0517mm minimum.

ACL Race Series performance engine bearings can be assembled with .00075-.001" per 1" of journal diameter (0.020-0.025mm per 25mm of journal diameter) plus .0005" (0.013mm)

Looks like the rods for cylinders #2 and #4 have slightly smaller BE diameters, I switched the rod bearings from #1 to #4 to see if it changed the clearance but got virtually identical measurement (which appears to be telling me it is the rod).



Spent some time this evening doing some research, and I've had a bit of a think about this, and I understand you can mix the extra clearance bearings with the standard clearance bearings according to the ACL information.

It is common practise to adjust oil clearances by mixing bearings of adjacent grades i.e. HX-STD with H-STD or H-STD with H-001 or H-0.025, to obtain desired oil clearance. Using the HX-STD with H-STD will give .0005" (0.013mm) additional clearance than using two H-STD shells, and similarly using H-STD and H-001 will reduce clearance .0005" (0.013mm). This, in effect provides the engine builder with 5 potential clearance grades* of 0.0005" (0.013mm) increments.

https://aclperformance.com.au/faq

Going with the following combinations of H-STD and HX-STD bearing halves gives me the following clearances which are much better.

I've packaged my rods up anyway for the machine shop to double check for me but looks like I will be ordering a set of the HX-STD bearings so I can tune my clearances.

dlknight

After my holiday mid-august had a little break whilst I waited for the machine shop to finish the cylinder head and check the rods out. In the meantime, I decided to take a look at the front brake discs, tidy them up and paint the bells silver like the rear discs.



They tidied up really well with a wire brush and a flapper wheel on the outer edge, however when I checked the cleaned-up brake disc with the micrometer they were only just within spec (around 30.6mm). So I ordered a new pair from autodoc for £160 (ATE brand), plan is to paint the bells of the new discs the same as the rears and then I can fit them and the repainted front calipers!

Another job was to reassemble the belt tensioner after vapour blasting and plating of the disassembled parts, came up excellent, was pretty tricky trying to get the large spring back into place as takes a lot of force to compress it!



Cleaned the oil pan and baffle to remove any traces of vapour blasting material and reassembled (with red loctite on the screws).



Sneaked in a couple more jobs, replacing some of the a/c o-rings at the bulkhead and installing the re-plated hood catch.

dlknight

I previously had the brake cylinder heat shield cerakoted and was going to reinstall it but noticed the rubber piece (presumably to stop the shield vibrating against the brake booster) needed replacing. After using Google image search it turned out this was either a rubber seat bumper from a motorcycle (looked most like a Yamaha from the 70s) or a rubber seat bumper from a VW van from the 60/70s. I've ordered the VW one as it would seem the most likely, will find out if it fits (when it arrives) part number 211 881 895A.







Popped over to Knight Engine Services and picked up the last bits of the engine including the cylinder head and the rods which had been checked and passed with no issues.







Cylinder head inlets have been flowed, ported and larger valves fitted, my original head was cracked and luckily, I had a spare head with Andrew Sweetenham's name on it, so that was used for the rebuild. You can see the crack on my original head below, between the water jacket and a bolt hole.







Extra clearance rod bearings arrived swiftly thanks to David! thanks very much appreciated and the packet of sweets!



Next day I drove up to Tamworth to collect some spare panels which may come in useful at a later time.



Most of the day was spent measuring and working out the rod bearing clearances, see below for the final calculations. My micrometer technique has improved so I'm far more confident about these measurements which were verified by the plastigauge later.

Spent the rest of the day re-assembling the rods and pistons, then began installing them into the block!

Installed piston #4 first on its own and made sure the rotating assembly turned freely, then followed up by installing piston #3 and #2 together, finally following by piston #1 the next morning. Check the clearances using plastigauge with each rod, then assembly lube followed by final torquing verified with the stretch gauge.

Used plenty of engine oil this time on the piston skirts, rings, cylinder bores and ring compressor and the pistons installed easily.









I used my stretch gauge which I'd imported from Summit Racing at great expense, but possibly wasn't required as I was achieving the ARP recommended stretch value at the recommended torque.

Final rod bearing clearances below - after reading the ACL documentation, they suggested that it is a common technique to buy sets of different clearance bearings e.g. H-STD and HX-STD, standard and extra clearance. Using one half of each to achieve the desired bearing clearances, the thicker bearing shell goes on the top and the thinner at the bottom.

ealoken

Great work!
Keep it up!

dlknight

More work in the lair (garage) once more!
My rubber seat bumper from a VW van from the 60/70s arrived part number 211 881 895A. Looks very similar to the one I took off the brake booster heat shield, although slightly larger. Haven't fitted it yet but I'm optimistic it will fit!



Now I had all the parts back it was time to lay all the clean aluminium pieces out to compare with when they were disassembled from the car late last year.

BEFORE & AFTER


Then onto the next bit whilst I waited for some genuine seals for the oil intake and outlet tubes. Decided to get stuck in and assemble the compensating shafts (balance shafts). I used the Loctite 638 as specified in the workshop manual, although I have heard of people using the alternative flange sealant that is used for the oil pump and lower crankcase section. This was spread onto the cover sealing surface using a mini roller which gave a nice thin layer. Bearings and journals were lubed with some assembly lube before installing the cover. As per the workshop manual the bearing covers were loosely installed with an oiled o-ring and pushed fully home before tightening the covers following the torque procedure.











I got carried away and installed the oil filter console next using the special tool to align the housing.



Paranoia got the better of me and I had ordered a brand new oil thermostat from Porsche, installed this and torqued the cap with a new sealing ring to 80Nm as per the Porsche 928 workshop manual (yes you read that right, for some reason Porsche omitted the torque figure from the 944 workshop manual but it is luckily included in the 928 WSM).



Parts arrived from Porsche so I was able to continue and attach the oil intake and drain tubes.



Then I spent the rest of the afternoon installing the sump, I used a method I'd read on rennlist. I lightly oiled the gasket first so it was wet but not dripping wet. Then loosely installed the gasket on the crankcase, spreading it out correctly. Installed the sump carefully so as to not damage the inlet or drain tubes. Then began to install the bolts by hand, pulling the gasket as needed with a pick tool. I went round several times until all the bolts were tight by hand. Then torqued to 5Nm (my torque wrench didn't go as low as 4Nm as per the manual), again went around many times following the order in the procedure until all the bolts were tight to 5Nm. Then moved up to 10Nm (discrepancy in the workshop manual as the specs at the beginning say 10Nm for step 2 but the procedure in the correct chapter states 8Nm, I went with 10Nm), again seemed like an age going around multiple times until every bolt was 10Nm and there were no more loose bolts. Gasket looks great with no bulges or sticky out bits, ran a paper towel around the edge several times to soak up any excess oil which had squeezed out.



I'm now ready to measure for the head gasket, I think I'm going to go with a Cometic MLS gasket but just need to work out the correct thickness.

I've measured the wear indicator on the cylinder head at around 23.35mm so slightly below the wear limit in the workshop manual (23.6mm). I've ordered a few parts to make up my own CC'ing kit to measure the combustion chamber capacity. I'm also going to measure the piston level at TDC and measure the piston bowl capacity to give me the figures I need to work out the compression and "squish" factor.

Bits for CC'ing kit -

100ml burette with PTFE tap
Burette stand (not strictly required but wasn't that expensive and makes things easier)
Green food colouring
Isopropyl Alcohol (already owned, for cleaning records, another hobby of mine)
3mm clear perspex cut to size, to seal combustion chamber
Used spark plugs (from this car)

If you made it this far, some tips I found. The victor reinz gasket set doesn't include everything you need to finish the build, and some things like the oil pickup tube gasket are not as good quality as the Porsche ones.
I've ended up ordering the following additional items (specifically for a turbo car) -

1 x O-ring (oil return tube) 99970707940
1 x seal ring (oil pickup tube) 94410713605
1 x Seal (oil level sensor gasket) 94410123302
1 x seal ring (oil sump plug seal) 90012311830 (these are 22 x 27 so should be able to obtain from hardware store)
2 x seal ring A 26 X 32 (turbo oil return pipe) 90012304930 (should be able to obtain from hardware store, I ordered from ebay)
1 x seal ring A 18 X 22 (oil breather pipe) 90012314030
4 x seal ring A 14 X 18 (turbo oil feed pipe) 90012300730
2 x O-ring (turbo o-rings) 90017405840 (these are mega expensive, presumably because they are odd size 25x3.15mm)
2 x seal ring A 22 X 27 (oil cooler seal rings) 90012301130 (should be able to obtain from hardware store, I ordered from ebay)
1 x O-ring (turbo oil feed seal) 99970704340

sm

Your before and after picture of the clean parts reminds me of this picture. Very cool!