OIL PRESSURE: If you’ve lost oil pressure after a service and have tried all the obvious culprits – pump, drive gear, woodruff key, pressure relief valve and pressure gauge, here’s one you may not think of. There are 2 types of rear camshaft bushes! If you fit the wrong one for your crankcase, you can finish up with no oil pressure. So check the rear bush to ensure it is a good running fit on the camshaft and a close fit within the crankcase avoiding oil by-passing the bush altogether. For 3-bearing engines, check the oil feed pipe to the centre main is seated well and not fractured. |
OIL PRESSURE: The "spit and hope" type lubrication of the Seven makes it most important to keep a watchful eye on your oil pressure gauge. You will soon see that when the engine is cold it swings off the scale but, as the oil gets hot and thins, the pressure drops back to less than 5 lbs under normal driving conditions. This is quite normal. However, when hot, should it uncharacteristically rise dramatically, immediate measures need to be taken. One of the most important items to carry at all times is a length of 1/16th rod or stiff wire about 6-8 inches long. A sudden rise in oil pressure usually means that there is a blockage in one of the oil jets supplying the big ends and, if left unattended, this would cause starvation and big-end failure. These jets are covered by 2 small brass bolts on the offside of the engine crankcase either side of the oil filler tube. To clear a blockage, turn the crankshaft 1/4 turn on the starting handle, undo the bolts and carefully poke the wire down through each of the jets—it should go down about 3 inches plus, (it may take a few attempts to get the feel of it and locate the holes, why not have a dry run at home as practice?) This will ensure each jet is free of obstruction. Replace the bolts and start her up and check the gauge. Hopefully this will avoid an expensive engine rebuild!! Gary Munn |
RE-FITTING PISTONS: When re-fitting pistons—confused about the thrust side? Always re-fit pistons with the split skirt nearest the camshaft—sorted! |
GUDGEON PIN:Probably the worst disaster that can happen on your engine is to have a gudgeon pin clamp bolt work loose and come out. On its way out it will probably bend the con rod, score the bore and break the piston. It will drop on the gauze filter, be picked up by the crankshaft and smash a star-like crack in the side of the crankcase. The answer to this is not to use locking tabs but to ensure that you have new high tensile bolts fitted with spring washers and do them up really tight using ‘Loctite’ etc. on perfectly clean threads. |
OIL JETS:Jack French recommends turning the little oil jets that squirt oil down onto the troughs in the crankshaft 20 deg towards the crank centre-line (Mike Forrest says 30 deg, so take your choice!) to increase the period during which the oil is squirting into the troughs. I use a piece of hollow rod which fits over the jet and bend it slowly. First clean up the ends of the jets where previous owners will have walloped them trying to remove the crank and after a gentle bending, test them by inserting a suitable piece of thin straight wire to check alignment. |
CLEANING: For cleaning the waterways you can use a mild acid as found in brick cleaner or patio cleaners found at builders merchants. |
REMOVING CYLINDER HEAD: When removing A7 low compression, 18mm, cylinder heads, to save hammering a screwdriver or chisel between the joint, try using the hook end of a Ruby boot key into the plug holes of numbers 1 and 4 alternately. Even better, get 2 boot keys and make it even easier. This dodge does not work for 14mm heads. |
SUMP NUTS: In replacing the sump, I’d fitted new set screws – those nice long-headed ones with the oval washers. What I had forgotten, was that for the centre rear one, you have to use a short one – otherwise, yes you’ve got it, the tip just catches on the starter ring…… |
TIMING GEARS: Before undoing the timing gears, remove the fuel pump entirely from the crankcase and don’t replace it until after the new gears have been firmly installed. If you don’t do this, the camshaft may move backwards once the timing gears have been removed allowing the petrol pump cam-follower (lever-thing) to slip to one side of the pump-drive cam and jam things up! Even after re-fitting the pump it will be judicious to check things are where they ought to be by gently turning the crank by hand. If the cam follower has been displaced, a firm ‘clunk’ can be felt as the crank hits the obstruction. |
ALUMINIUM PULLEY: To release the large aluminium pulley at the end of the camshaft, hit it sharply sideways against the edge of one of the holes so as to try to rotate the pulley on its shaft rather than trying to hit it from behind along the length of its shaft. |
CAMSHAFT BUSHES: Should you be building a 2-bearing engine from spare parts, make sure you have the correct camshaft bushes fitted at the front and back of the crankcase as there are two different sizes: the earlier crankcases (with the starter inside the car) have a smaller outside diameter for both front and rear bushes than later engines (with the starter under the bonnet) and the front bush is also slightly shorter. It is important not to confuse these with the ones fitted to the later crankcases as they look the same to the naked eye. Should the earlier ones be fitted in a later crankcase by mistake, there would be no oil pressure as the oil would simply flow down the sides of the bush. The inside diameters are the same on both crankcases. If in doubt, the bushes should be a snug fit in the crankcase in both instances usually requiring a light tap. Also check that you have the bushes the right way round as the oil holes must align with the holes in the crankcase. Another useful tip is to replace the square peg bolt that secures the front bush with a 3/16 inch Whitworth bolt of exactly the same length, and then tap a 3/16 inch Whitworth thread into the larger peg hole in the bush. This allows the bush to be bolted up tight after assembly. Bolt the rear bush into the crankcase first, making sure that you line up the oil holes, fit the front bush on to the camshaft then “glue” the 9 centre rollers into their slot in the shaft with grease and lower the assembly through the front of the crankcase taking care not to dislodge the rollers, carefully lining up the front bush as you lower it in so that the bolt holes line up. If you are lucky, the rollers will slide into their cage first time but it could take several attempts! Screw the new bolt and a fibre washer into the front bush - job done, simple. If you are building the later 2 bearing engine, you will need the camshaft with the extra cam to drive the mechanical petrol pump. The 3-bearing engine is different again, but that’s another story. Glyn Llewellyn |
OIL FILLER TUBE: So how does one remove that thin-walled oil filler tube without collapsing it and rendering it useless? I managed to find a piece of heavy gauge pipe which just fitted inside and after making sure nothing nasty could drop into the engine and with pipe in place I was able to unscrew the tube with an oil filter remover without crushing the tube. Richard Bishop |
CORE PLUGS: If you are having problems getting your core plugs to seal the following clever solution was offered to me the other day. Soak some strands of string in Hylotyte Red (replacement for Red Hermetite which is no longer available) and roll into a sausage shape. Clean the recess in the head thoroughly and allow it to dry. Line the inside edge of the recess with the wetted string where the new core plug will bear and fit the core plug in the normal manner. Tap it down with a suitable drift (suitable being about the same size as the plug) until the domed surface is flat. Leave for 24 hours before refilling or topping up engine with water. It should now be watertight. Hylotyte Red remains flexible and is easier to remove than Red Hermetite. “With many thanks to ‘Bumbling’ of the A7OC”. |
THE CASTLEMAN CLIP:
When
I saw a trickle of oil from one of the oil jet plugs I just thought![]() |
CRANKCASE/BLOCK
REAR NUTS: I always seemed to have difficulty getting the back
nut to the Crankcase/Block really tight, there seems to be so little room to
get a spanner on and or to move round. So my solution was to use one of the
'long' nuts from the tappet![]() |
OIL PUMP:
When you assemble your oil pump
don't forget: radiused shoulders to the top, no gasket under the cover
plate. |
CYLINDER HEAD NUTS: Use three or four steel washers under each nut on the A7 cylinder head. With the washers in place, if a thread does strip all you have to do is to remove the washers and use a new nut on the undamaged part of the thread which had been covered by the washers. Presumably the reverse is possible using washers to cover stripped thread so that a nut can be placed higher up the stud on good thread. Bart Walsh Essex A7C |
CHECKING COMPRESSIONS:
Here is a simple test if you suspect your engine is low on compression
which will determine if it's your rings or valves, without having to
take the head off. CRANKSHAFT
BEARINGS: The dual-purpose races at the front end of the
crankshaft
MODERN LIP SEALS:
fitting one of the modern lip seals with matching cover plate, available
from our usual suppliers, it will be noticed that comparing the new
cover with the old, there is no cut-away for the oil return to the
crankcase which, if you look with the cover off, is rear of the rear
main bearing outer at about 5 o’clock. Carefully mark the new cover
plate and file or grind the ridge on the plate to align with the oil
hole in the case - this will encourage return of the oil to the sump
when fitted. We always retain the oil dish thrower (outer dish towards
you). Do not over-paste the cover with sealant or the goo can creep and
block the oil return hole which, of course, you have previously ensured
is clear. Try the seal on the flywheel boss before fitting to ensure you
have the correct one and the boss is smooth. Apply a tad of grease where
the lip will seal. Gary Munn “Munwellyns” CYLINDER HEAD NUTS: When nuts are tightened down,
the threads on both the stud and nut are stretched a little and it is
good practice to replace each nut not only on the same stud but also the
right way up. (Ideally, one should always use new nuts but ….).
Solution: drive 11/2“ nails 1/2
inch into a block of wood in the correct
pattern of the head studs and when removing the cylinder head pop each
nut and its washer on its correct nail and the right way up. As a bonus,
write the number of order of tightening the nuts with an indelible pen
beside each nail and the word “FRONT” just to be certain.
David Whetton DA7C (with apologies if every other owner wh has
already done this).
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FITTING EARLY
CAMSHAFT ROLLERS: Having trouble placing the rollers around
the centre
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CHEAP PISTON RING
COMPRESSOR: An e FITTING CORDS PISTON RINGS: New old stock Cords piston rings are for a Reliant so there are only 3 rings per piston in the set - no scraper ring below the gudgeon pin. The top compression ring supplied has a ridge dodger step. I deglazed the bores before fitting the pistons from the bottom of the cylinder, much easier than from the top as the bottom of the cylinder has a chamfer to help ease the rings into the bore. Some people have reported lack of power after fitting Cords rings, but my car seems fine. I will discover how much the oil consumption has improved after the next run. Roger Ballard DA7C FITTING THE BLOCK: I
fitted the rings, pistons, conrods and baffles to the block, then stood
the crankcase on the flywheel end, the block is arranged on pieces of
wood to lift it level with the crankcase. The units are pushed together
until the rod big ends are inside the crankcase then fit the baffles
with a dollop of grease. Finally, continue pushing the block and
crankcase togeth |
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