As the UK entered the 1st 2020 Lockdown, Frosch decided to be naughty… as I was driving it back from work, the engine lost all compression, coolant boiled and sprayed the engine bay... Lovely, head gasket failure in lockdown 😡😤.
Initial mechanical investigation highlighted the gasket had failed between cylinders 3 and 4 😩however the bottom end remained undamaged 😊.
New Copper gaskets and various other gaskets were ordered
along with new studs. The engine was put back together however, after a couple
of test drive, it was noticed that the coolant temperature was stable about
75/80°C and when stationary, the temperature went up very quickly. This was not
a good sign…😱
The head was put apart again and inspected further to reveal
a crack on the combustion chamber of cylinder 3. Oh nooooo! Head was scrapped…😤
What is this Engine???
A new head for small bore engine was ordered from MambaMotorsport; this new head was to be converted for unleaded fuel, ported and fitted with mini cooper bigger valve and the compression ration had to be adjusted.
While talking to John @ Mamba Motorsport about the technical requirements, a detail came to my attention: the pistons were not dished as standard 948 piston but flat topped.😓
After measuring the bore diameter and the stroke, it was established that the engine had been rebored and fitted with flat top mini cooper pistons and its capacity is actually 998cc rather than 948cc. 😋
The scrapped head was checked too as at first glance, it had
double valve springs which was not standards on 948cc . The inlet valves were
bigger than standard 948 valves (27mm). The valves were 29.4mm, most likely
the valves fitted on Morris Minor 1100 engines.
The new head was to be fitted with ~31mm valves as found on Mini Cooper 998 and
spridget 1100.😊
The camshaft is the original 948cc (5.61mm lift / 230°
duration). At some point this will be swapped for a mini cooper 997cc cam
(C-AEG 567: 6.35mm lift / 252° duration) which has a little more inlet duration
than the 998c cooper or spridget 1100 came (252 vs 230 deg).
Although the new specification of the engine is very similar
to the one found in Mini Cooper 998cc, it is not quite there as the cam (8G712) is
lacking of lift and duration (0.75mm and 20° of duration). In order to
improve this a little without swapping the cam, the rockers were swapped for 12G1313:
Pressed steel rocker fitted in 1275CC engine. These rockers have a 1.27:1 ratio
rather than the standard 1.22:1. The ratio increment allows more valve lift: 25%
in between what is proceed by a std 948cc setup and 998cc cooper setup).😊
As the Engine was in bits, the 948c crank pulley was swapped
for a std damped 1275cc pulley and the distribution chain was changed.
The Carbs
The SU HS2 twin were checked and one was fitted with the old
fixed piston/chamber and needle and the other was fitted with the newer biased
version (spring loaded). Again some more signs of DIY bish bash bosh!!! 😤
Both carbs were rebuild to the old original fixed using a full rebuild kit
from mini spares (jets, needles, floats, gaskets) and the inlet manifold was
ported and polished as the aluminium casting exhibited several mismatches and
flashes.
As the car came with a spare LCB small bore manifold, it
would have been unfair if not un-ethical to deprive the new engine of such “performance enhancer”😇…
It was wrapped and fitted!
Sparky
John @ Mamba had a suitable electronic distributor gathering
dust on a shelf so it found its way to Frosch engine bay.
New plugs, new ignition leads…. Almost done.
As mentioned before, some elements of the wiring needed some
attention. While it was all functional, there were signs of repairs and
modification (German requirements) with you would expect after 60years of service. The main
ignition/light switch had been on back order for ever but, back in June 2020, I
managed to get a new one. 😀
The all wiring was inspected and the dashboards was rewired
properly.
Was it worth it?
In October 2020, the car was back to live, the engine reconditioning and the electrical update have made a real difference. The car starts easily even
when outside temperature is below 0°C. The engine feels stronger especially
went climbing a steep hill. Frosch really likes to be push around countryside
lanes… and the kids loves it: “VROOM VROOM me car” and “faster faster princess
car”.
😁😁😁
¿Next part of the
project?
I managed to acquire and old fashion Aley Bars roll cage (now Safety Devices) which could be easily modified to meet modern FIA Historic requirements but I am not sure if it is needed yet.
Frosch needs bit more sparky work; the fuel gauge does not
move much and seems to have a mind of its own. The sender in the fuel tank
seems to be the culprit. These senders cost about £35 so it will be swapped as a
matter of course when I finally find the time to fit the Panhard bar from PeterMay Engineering. To do the job safely, the fuel tank needs to be dropped which
is not a big job, just time consuming.
The front shocks will need servicing; flush the old oil and
fill up new fresh oil (motorbike fork oil). The Rear springs will be also
replaced.
