Our apologies for the delay in getting Episode 10 up for you all. We have had a busy few weeks with the final rounds of a couple of championships, finishing off vehicles for customers to take to the NEC, supplying traders for the NEC and our normal workload. I have not found the time to get this up; to make up for it, this weeks is BUMPER EDITION!! With all of that work, we have some exciting episodes to come with some incredible cars passing through the workshop; for now though, let’s get back to this trophy winner.
Catch up with the last entry at the link below and then follow up with the latest entry “On your marks, get set… STALL”
Last weeks episode…
Saving a Troubled Trophy Winner – Part 3 of 4.
One of the tasks set out on the initial job card, was to remove the engine and investigate why it was running poorly; the customer had complained in length about needing to blip the throttle at low revs and the lack of low-down power/torque. This Morris Minor was used regularly to attend car shows, where it would be in slow moving processions or on display with the engine running. The car was also used to tow a teardrop caravan for the longer shows, our customer said that the previous engine builders had been advised of its intended use and therefore it had been built with the above scenarios in mind. The customer was unsure what the exact specifications of the engine were as no paperwork had been presented to him; we decided to carry out our initial start-up tests and contact the engine builder so that we can compare our findings with those of the initial build to see where we are losing out.
At this point it is important to stress that some information pertinent to the history of the build and set up is purely based on information passed to us at the time by our customer and is the yard stick that we have to base our findings on to try and gauge what could have caused the damage
The customer provided the details of the previous companies that worked on the vehicle throughout its initial restoration and then through the modification stages thereafter. Much of the initial scheduled workload in our workshop was set out to remedy work previously carried out. We asked whether the customer would prefer to take the vehicle back to the relevant companies to seek any possible recompense or warranty claims; however, it was stated that the client would rather have the correctional works and modifications carried out at A Series HQ. There were reasons for the vehicle not heading back to those companies however we only take the vehicle and customer at face value at the time they come to us. The historical data for the build can be useful to ascertain specifics and time frames when presented with faults, we do not use third party information to discredit companies (or customers for that matter) many of whom we have good working relationships with. We document all of our work for various reasons, but the main ones are:
- Pride of work, to showcase the work we put out for our customers.
- To help our customers who keep historical folders of all works carried out.
- To show the condition of the vehicle when it comes in to us and when it leaves.
- Datalogging, for future use should we be required to show components used or work carried out. It is invaluable.
With the engine removed from the vehicle we installed it onto our test bed, this enables us to check the fundamentals of the engine using our tried and tested ancillary items; removing several levels of uncertainty from the run up. Before starting the test (which would be running our fueling and ignition systems) on the engine we took an oil sample for reference should it be needed further down the line depending on our findings.
Through the initial run up, the engine showed no signs of leaks along with good temperatures and pressures. The running was very erratic both on tick over and through the rev range. We allowed the engine to cool down and measured the valve lift to try and gain a sense of reason for the erratic tick over. The engine had sintered rockers fitted (ratio of 1.21:1) and the measured lift at the valve was showing large discrepancies which indicated wear to the camshaft but suggested we were looking at a camshaft in the region of the SW5 or MD276. It appeared unlikely that this should be the main cause of the erratic running.
We set about completing another short stint with the engine, the usual adjustments were made (timing, fuel mixture) but this was showing the same symptoms that our customer had been complaining about routinely since that first time we saw the car at a club event. The engine was powered down and we carried out one last check, without being more intrusive to the engine, a compression test.
The compression test indicated that there was something wrong inside the engine. A straight forward compression test is not 100% accurate but it is a quick way of understanding what is happening inside the engine. It will show which cylinders are holding pressure and you can usually determine whether it is a head gasket failure or wear in the cylinders/rings that is the culprit. From the information we had gained from our customer about the build and our years of building A Series engine’s, for this application we were expecting a figure anywhere between 9:1 and 10:1, Depending on the camshaft and various other setup parameters.
Compression test results: The results were interesting from this engine as the compressions were very low across all bores; 7.5:1 to be exact. The low compressions and the noticeably worn cam lobes raised questions but started to explain the erratic tick over.
We spoke to our customer and mentioned our preliminary findings, we suggested that we remove the cylinder head to check the condition of the bores and remove the sump so that we can check the condition of the shells.
Here are the strip down photographs…
As you can see from the above pictures, things were not quite as expected for such a young engine. When our customer mentioned the running issues we thought that this would be relatively straight forward, either the carburettor incorrectly set up or the wrong camshaft being used for the desired application. Upon removing the cylinder head, we noted excessive wear and glazing in the cylinder bores and a large amount of carbon build up in each combustion chamber and on the top of each piston.
Moving through the engine there was heavy wear on the shells, (mains more than the big ends) the camshaft was worn consistently on all lobes as were the camshaft followers. It was very clear that there had been a contaminant in the oil; there were several things that could have been the root-cause of this, however prior to sending the oil away for analysis these would be speculation but for your reference the main causes of oil/lubrication breakdown are:
- Incorrect oil being used. Either the wrong type or simply a poor-quality oil. You should be using 20w50 mineral oil. There are some good cheaper oils but as a general rule of thumb anything under £15.00 per gallon isn’t worth touching. We know it might be tempting to use a cheaper oil if your engine has an oil leak, our advice, fix the leak and use a good quality oil. We recommend Castrol Classic, Comma Classic, Valvoline and Pennine Lubricants. They are all blended to include exactly what your engine requires.
- This Morris Minor came to us for the sole reason of fixing all of the gremlins. We run a no-nonsense workshop. If your car has a fault our team will find them and will fix them. This Morris Minor had a blocked radiator, if your radiator is not performing to its optimum you will find that your engine is not able to cool and run at its optimum temperature; this can have several ill-effects including oil breakdown (losing its viscosity)
- Incorrect fuel/air mixture. This has several ill-effects however the one leading to oil breakdown is running too rich for prolonged periods. The common misconception is more fuel more power. It is quite the opposite, no matter the state of tune of your engine, your fuel/air mixture will have an optimum to burn correctly. Too much fuel in your mixture will result in bore wash and once those rings have broken down you will lose compression and the carbon and resulting debris will be able to pass into the oil below. The addition of petrol to the oil not only dilutes the oil (reducing the lubrication value) but petrol also has cleaning properties which will wash any deposits in the block into the oil.
At this point we requested another site visit from the customer so that he was fully aware of the condition of the engine and the routes forward from here. The customer came down with a friend, both inspected the engine and the rest of the works to date. The plan of action was put forward, the customer stated they wished to have the engine built back to the same specification rather than one of our preferred, tried and tested builds. The customer requested this due to the cost of the pistons in the previous build. We clarified that the engine would require machining and the majority of the component parts replacing. The customer agreed and even picked his new engine colour and dress up parts. We explained that this build was not a common build, the pistons were unknown to us but we would contact the previous builder to get the information together to recreate that specification.
Before leaving, the friend approached us and stated that the set-up had always been an issue, he put it down to our customer previously having his SU carburettor (HIF44) sandblasted, this became apparent when we stripped the carburettor down.
We were unfamiliar with the pistons used in this build, they had a very deep dish and at first glance looked similar to low compression MG Metro Turbo pistons however they measured up different. What caught our immediate attention was that the pistons and bores measured up to 1330cc (60 thou oversize from standard) yet the piston top was stamped “STD” which indicated to us that these pistons were not originally designed for the A Series.
We phoned the company that our customer had stated supplied the engine, they informed us that they only installed the engine, that it was a tried and tested build and that the engine was built for them by a reputable company; just down the road from them. We were given the contact details for the engine builder, we phoned them but they seemed disinterested and stated that they do not keep records of their builds. We clarified that we only needed information of the specifications and were not interested in the history but we were still unable to gather any information about their tried and tested build.
Our customer was able to locate the UK distributor for the pistons and passed the information over to us. We contacted the distributor and shared the information we had; based on the measurements and calculations from the strip down of the engine. The distributor stated that these pistons were commonly used only in high performance engines, they recommended a camshaft and said that due to the combustion chambers, naturally-aspirated engines using these pistons required a lot of work to the cylinder head to get the compression ratio up.
We were instructed by our customer to do the bare minimum to the engine in terms of machining, machine what was required and build back as it was due to the price of his previous build and the cost of the pistons. We put the engine through our machine shop and carried out the following works:
- Reground the crankshaft
- Refaced the block
- Honed the bores; These were measured and were at the limit of their tolerances for the pistons / rings.
- Remanufactured the cylinder head. New valves (inlet), springs, guides and refaced. Keeping the specification of the previous build.
We built the engine back up to its previous specification with the addition of a rota slide, Vernier duplex timing kit so that we could dial in the camshaft to allow adjustments.
Despite the engine not being one of our recognised builds, the engine was built up using the following new parts;
- Camshaft bearings
- Cam Followers
- Steel Rota Slide Duplex Kit
- Push Rods
- Main Bearings Shells
- Big End Shells
- Thrust Washers
- New Piston Rings
- Oil Pump
- Oil Pressure Relief Valve
- Water Pump
- Full Payen Gasket Set
- Inlet valves (4 of)
- Valve Guides
Here are photographs of the build…
The engine was painted and dressed up as per the customers request, installed into the vehicle along with new inlet manifold and carburettor due to the old carburettor body not being serviceable, we also replaced the radiator for a new unit.
The car was then booked in for a session on the rolling road to get it correctly set up ready for customer collection.
Tune in next time to see how the final preparations and set up went.
We have a huge range of engine bay products and accessories including replacement and performance engines.
See the engine bay section below.