It's about time I updated what has been going on with BART after the head gasket failure last year. I decided I was going to take my time and repair BART properly so I set out and sourced some tips from the XWeb forum.
I tore down the head and checked for flatness, checked for bent valves and inspected the valve seats and guides.
As it turned out the head was flat at less then 2 thou out of true but I elected to get it skimmed by 4 thou just to be safe. The machine shop who did the work checked the guides and seats and found them to be OK but I elected to install new valves and springs after discovering Cylinder number 1 had a bent exhaust valve!
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| Old Valve uneven lapping marks |
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| Not seating correctly = bent |
It wasn't bent that much but needed replacing so all the valves where replaced as a precaution. New head bolts and studs where used as well along with new valve springs and shims.
The key points to performing this job well where to ensure the valves where lapped in properly, getting the head skimmed and ensuring the block is flat and cleaned.
I cleaned the block with Stanley knife blades and used a spiral bottle brush on the end of a drill to clean out the head stud and bolt threads in the block. The goal to be able to screw in the studs by hand with out any stickiness or grit on the threads, this helps achieve the correct torque for the cylinder head.
Also important was to ensure the two head locating bowls sat correctly and where not so tall as to prevent the head from seating down fully. One of them had indeed deformed and was preventing the head from seating so both where replaced.
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| Valve lapping the old fashioned way |
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| Skimmed, new valves and springs |
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| Cleaned block and pistons with gasket and studs read to go |
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| Locating dowls needed replacing |
I used ARP assembly lube on all the threads, I highly recommend this as it helps achieve even torque across all the bolts and studs. Also, lube under the nuts and on top of the washers where there is a turning friction force, again to achieve even torque.
It is possible to complete the initial torque sequence with the camber off the head without any special tools other than the torque wrench but with the cambox fitted you need to use an extended offset ring spanner (Continental Engine base spanner) Luckily these are available here:
https://www.lasaero.com/products/article/Q01GIQ979
These work perfectly, I required the 3/4" or 19mm spanner
I torqued the head down in three stages (29 / 47 / 69 lb-ft) following the FIAT recommended pattern.
I took the opportunity at this time to replace the water pump and replace the alternator wiring as it was looking very crusty with poor connections. I installed new alternator brushes and a new timing belt.
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| New Water pump and cleaned up alternator |
After everything was back together I refilled with coolant and changed the oil for good measure. BART started first time! I ran him up to temperature and drove around the block for a mile or two and then put him back in the garage and waited 24hrs.
The initial heat cycle and retorque is key to ensure the head gasket seats correctly. Heat cycle the engine once, let it cool to stone cold over 24hrs then retorque. Do this by backing off individually a head bolt by 1-2 flats (90deg) and then retorque immediately IE: one bolt at a time in the correct sequence.
Another tip is to mark the nuts and bolts so as you have a reference of how far down the gasket snugs following the torque cycles...
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| Use engineering marker pen, dab on the stud and nut |
With that done it was now OK to drive BART for a few hundred miles before the third and final torque sequence; doing exactly the same as above, back the bolt off immediately torque to the correct spec.
The few hundred miles I needed to put on BART before the final head torque took on a bit of urgency as I was contacted by the UK X1/9 owners club if I would like to display BART at the NEC classic car restoration show in March. Having attended the NEC show in November with BART before I jumped at the chance for the March show and made plans.
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| On the stand with BART |
