Posted By : Chris Taylor, 21-Nov-2005,
05:14pm
Anything you do will only stave off the inevitable rebuild. You can make sure you have good quality oil, that your cooling system is up to scratch,
even fit an oil cooler to minimise the loss of oil pressure when hot. Alos, make sure you have a decent oil filter with the corrcet anti-drain valve. A
new oil pump would help, especially if you fit a Spit 1500 (higher capacity), and while you're at it, make sure the pressure relief valve is sealing
properly. You can drop the sump to fit a new oil pump with the engine in the car.
It's also possible to replace most if not all the bearing shells with the engine in the car, but I don't recommend it. Messy, front ones difficult to
get at, and difficult to maintain the necessary cleanliness.
The crankshaft nut is renowned to be a ********. It is a normal right hand thread, and requires simple brute force. Some people have managed to loosen
it with a big hammer and well aimed chisel, but go for either the big Stilson and block of wood (aided by a long metal pipe on the spanner handle) or
even better, get the garage to do it with an air powered impact wrench. It's WELL worth it for ease and peace of mind, whatever it costs. (Do try it
yourself first through, you might just be lucky!)
Before assuming that the crank needs regrinding, you need to measure (or get it measured) with a micrometer. You may find that if the wear on the
shells is slight (ie engine is not noticeabley knocking under load) that the crank is unworn. That way you need only replace the bearing shells. Any
decent engine re-conditioner should be able to advise you, but that does mean taking the crank out and taking it to them. They may advise just
polishing the journals. If they are a good firm, take their advice. They can probably also supply shells to match. If not, suppliers like Canley and
Rimmers can provide most shells for your engine. You'll be able to work out if they are standard or -10, -20 thou etc from the micrometer measurements,
but failing that, any undersize will be marked on the back (ie non-bearing) side of the shells. No marking (although it might be "std" ) usually means
standard size (ie 2.000" for mains, 1.625" (?) for big ends). Don't assume that big ends and mains will have been reground to the same undersize,
although it would be VERY strange to have individual journals at different sizes.
While you've got the engine in bits, change all the likely bits as well unless you can vouch for the individual bits. Timing chain and tensioner, oil
seals, gaskets, perhaps an oil pump (but you can check the tolerances against a good workshop manual, so don't assume it's worn) etc.
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Posted By : Andy Vowell, 21-Nov-2005,
07:55pm
Personally I always change the oilpump at engine rebuilds or at least the internals that can be bought separatly. As mine is a race engine that
gets a build every 1 1/2 years I now have a nice stock of used pumps, but as one of THE most important componets I feel re-using an old pump is not
worth the saving. I agree with Chris that the newer alloy bodied pump is a no brainer upgrade.
If you are really strapped for cash, a can of STP oil treatment may thicken up your oil and quieten down the engine for a while.
Andy
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Posted By : Gavin McFarland, 21-Nov-2005,
11:43pm
If it's not a silly question, how would one check if the oil pressure relief valve is seating properly? I've had mine out, cleaned and put back in
but I still get a bit of clatter on startup if I don't let the pressure build first.
Would a 1500 pump fit any Spitfire engine? I've got a recessed block 1300 from a MKIV...
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Posted By : Colin Wake,
22-Nov-2005, 09:04am
The 1500 pump will fit all 4-cyl engines.
Colin