The Engine
On purchase, the engine / drivetrain was in the car (I hasten to add that it wasn’t installed, merely sitting there!).
The story was that the PO who had started the restoration, had ‘done’ the engine. Evidence to support this was in the form of invoices from AH Spares for quite a variety of new parts from bearings to core plugs; pistons to valves etc.
Now in the early photos of the car in my garage, the engine is no-where to be seen. That is because this was the same PO (supposedly and Engineer by profession) who had done the replacement of the floors and based upon my inspection of that work decided to take no chances and sent the engine off for a proper inspection. So, the Healey (plus boxes of bits) came home to me and the engine went on its separate way – as transport was free and available!
Fortunately, close to what was at the time home in SW Scotland, was a small Engineering company – Thomas J McKean, Engine Rebuilders. It has been run for many years by his son John. This is the sort of place that you would have passed many times but never given it a second thought – I had!. Inside was like a travel back in-time regarding heavy engine (eering) equipment – not a computer control in-sight. In-fact it also appeared to be the meeting / tea / coffee place for quite a few, shall I say elderly gents – goodness knows how any work gets done.
However, John clearly had many many years of experience and quickly dug out an original BMC works manual. A quick removal of the head told the main story – yes there were new piston installed but the bores hadn’t been touched and a ridge was clearly evident near the top of each cylinder.
As expected every-thing would need to be stripped and re-build properly. At this stage, it all went into a corner whilst I decided what I wanted from the re-build engine.
What did I want from the engine – that’s a good question – so some thinking and research required.
Sounds logical, but that probably helped confuse things a bit more in the initial stages as there is a lot of advice around but not all in agreement!
I did find a helpful article by Richard Hockert Building a Competition Engine, or Maybe Not! on the NTAHC web site helpful;
www.ntahc.org/techtips-03/ What I can up with was:
- Solid reliable fast road engine. I am not likely to want to go beyond 6000 revs.
- Smooth, rev’s easily, and keeping power and torque through the rev band – not all at the top end.
- Keep to the triple SU concept (it is a tri-carb after all), but allow for larger.
- Improve on the 132bhp original.
Oh and I planned to link the engine with a Toyota 5 speed.
Now some of these things may conflict so getting a balance was / is going to be important.
I guess like always there is good and bad news from the strip-down. The positives were that most of the major parts block, crank, camshaft looked OK, but the block and head would need a good internal clean and all of the surfaces need machining. So, what has been done….
Head.
Whilst I would ideally have liked to put on an aluminium head, finances weren’t going to stretch this far and the original looked OK on inspection. Porting and polishing were the order of the day (if I took one thing from the above article it was Flow, Flow, Flow ….and this can be achieved just as well on an iron head as an Aluminium one).
The head, along with a new set of 1.75” SU intake manifolds were sent down to Peter Burgess (http://www.mg-cars.org.uk/peterburgess/indexstart.html ) for this to be carried out. Peter is more commonly known for his work on A and B series MG heads but through a friend he did the porting and polishing on for the Healey and aligned the intake manifold.
The head was then transported back to John for building.
Block.
The fully stripped block was sent out to be fully cleaned / cleared out!. On return John did some measurements and confirmed that the bores would clean up nicely at 84mm (about 26 thou oversize). Having given me a ‘shopping list” of the ‘specialist’ parts he was going to need, John continued with the engineering work on the block and crank etc. He was going to source bearings etc.
Now there is nothing like having an impending engine build with a list of parts in one hand and the DWM catalogue in the other. Self-restraint is definitely required!
Some of the things that did get ordered though (although not all from DWM) ……
- Pistons – Omega forged 84mm
- Aluminium sump plus baffle
- High capacity oil pump
- Competition timing chain
- Hydraulic chain tensioner
- Camshaft Vernier gauge
- Balanced lightened flywheel (note original weighs 12.5kg / 28lbs and the lightened one comes in at 9.4kg / 21lbs) – a useful lightening, plus it is drilled for a more modern clutch*)
- Pro-Race damper / pulley
- Spin-on oil filter kit
*I initially went for an AP racing 9.5” clutch (as per BJ8) but the cover plate is too deep for the Toyota conversion bellhousing, so this was sold and a Toyota item sourced instead).
All of this supplemented by the usual gaskets, plugs, seals etc. including a Payen head gasket which I managed to secure.
The original camshaft wasn’t in too bad a condition and a good candidate to be re-profiled. Looking at the options available, see table below:
After some advice, I plumped for the Kent Cams AH2 profile with new cam followers.
Kent claim that the AH2 will give an extra 20bhp at the wheels – we shall see.
Although not mentioned on their web site, this cam is not far from the DWR8, which required valve pockets to be cut in the block. After some measurement, we decided that we would need these with the Kent profile and cut them in.
The one thing that John wasn’t equipped to do was dynamic balancing, so (once again through MG contacts) the crank, flywheel, pistons (incl. pins) and Con-rods were sent down to Steve at Engine Tech in Kidderminster.
Feedback was good, in that the crank was in good condition and didn’t need much work. The key things they did were to:
- Balance the crankshaft, flywheel and clutch cover
- Decarbonise the con-rods and bead blast
- Re-size con-rod big ends and check and adjust for straightness
- Refit new small end bushes and hone to fit gudgeon pins from new pistons
- Balance con-rods end for end
The whole lot then brought back to John for assembly.
Final assembly was by now underway. The block internals were rebuilt with Cam, Crank, Pistons con-rods, bearings etc. all installed.
The Aluminium sump was secured after fitting the new oil pump which was adjusted to fit. The timing gear was added and secured.
On rebuilding the ‘head’ we noticed that the rockershaft had some signs of wear, and although we could probably have ‘got away’ with it, why bother, when, with every-thing stripped it could be changed pretty easily – back to the DW catalogue for a Tuftrided rocker shaft.
Another modification I have added is a gear reduction started motor. This was fitted whilst work was progressing with the engine, to check on mounting position / clearances etc. As a result of doing this John decided to remove the ring gear from the flywheel and install it the other way around as the starter teeth engage from the other side. I know that you don’t have to do this as it will work as original, but it offended his engineering sensibilities not to do it..
Whilst the engine was in his workshop I wanted to get the Toyota gearbox mounted up to check that every-thing matched and dowel pins worked as intended. I’ll cover the gearbox in a separate write-up.
Ready for paint. .... then
A few bits of glitz did creep in to the rebuild – the outside Head nuts have been changed to plated domed (aka XK, which is where they came from). Some of the non-load bearing screws, such as those holding on the timing cover are stainless – we had to make up some stainless washers to fit. And John got carried away and engine turned the visible sections of the back plate!
I also managed to come across an original works type aluminium rocker cover which has clearly up nicely - albeit difficult to hold onto its shine! ... and the crankshaft nut - the one with the ears which were probably a throw-back to starting handles, had a quick turn in the laithe to get rid of the ears!
– bit too modern to show through.
