Looking for a 1300 Spitfire engine.
Discussion
There is actually little to choose between the early small crank and later large crank 1300s for road use. Yes, if you building an out and out race engine and want to hit 8,000RPM for every gear change it might be worth it (though large crank 1300s were as good at winning races in the old TR/TSSC racing series as small cranks - large crank engines also had larger port heads).
For road use I would go for whatever comes up - either small or large crank 1300s if you like revs. over torque, or the longer stoke 1500s if you like torque over revs.
The Triumph 4-pot engines come up regularly on eBay and don't normally go for much. Of course the Triumph 6-pot engines come up too and are a bolt in swap for the 4-pots (if the bonnet will take it)... Going this route you really want a GT6/Vitesse engine as the engine is canted in the big saloons so more to change.
For road use I would go for whatever comes up - either small or large crank 1300s if you like revs. over torque, or the longer stoke 1500s if you like torque over revs.
The Triumph 4-pot engines come up regularly on eBay and don't normally go for much. Of course the Triumph 6-pot engines come up too and are a bolt in swap for the 4-pots (if the bonnet will take it)... Going this route you really want a GT6/Vitesse engine as the engine is canted in the big saloons so more to change.
Also don't discount the 1500, I have a very very nice Oselli engine that I use in my autotest cars, it's lightened and balanced and has had a very hard life, it revs up very very quickly, it is a lot sweeter than any 13 or 1500 I have ever driven, has lots of power and is an absolute gem of an engine, it wasn't cheap but certainly disproves the old thought of them being weak engines.
The reason for going with the 1300 are two fold, 1 the bonnet line won`t take the 1500 and 2 the car was originally fitted with a standard 10 948cc engine and then an 1147cc (my dad built it from a kit in 1958). The 1300 looks outwardly similar to the 948 apart from the exhaust being on the opposite side and it makes it more useable as the 948 wouldn`t pull the skin off a rice pudding........Martin
kartman24 said:
The reason for going with the 1300 are two fold, 1 the bonnet line won`t take the 1500...
1300 and 1500 are exactly the same externally. Even the piston/bore diameters and spacings are the same - only difference is stoke of crank so if a 1300 will fit a 1500 will too. The bonnet would only be an issue if you were trying to squeeze one of the 6 cylinder engines in.kartman24 said:
The 1300 looks outwardly similar to the 948 apart from the exhaust being on the opposite side...
To the best of my knowledge all the Triumph SC engines, from the 800cc unit in the Standard 8 up to the 1500cc unit in the late Triumph Spitfires and MG Midgets shared the same non-crossflow design with inlet/exhaust manifolds on the right hand side looking from behind the flywheel. The only major internal changes were to the bore centres with the move from 1150cc to 1300cc (though could have been the 950cc->1150cc).Edited by //j17 on Wednesday 13th August 09:02
http://www.totallytriumph.net/spitfire/engine_buil...
The Moss Spitfire parts guide also has a good tuning section - https://www.moss-europe.co.uk/Pdfs/Spitfire/spi06_...
The Moss Spitfire parts guide also has a good tuning section - https://www.moss-europe.co.uk/Pdfs/Spitfire/spi06_...
Be careful, you need to watch your overall gearing and strength of back axle.
All the 800 to 1500 engines share the same block dimensions, but the bhp and torque figures vary somewhat.
Generally the best engines are small crank 1300 as they have an extra 5bhp in the bottom end above a large crank version, and the 1500 with lots of torque. If you've got a 948 back axle I would guarantee you will break rear halfshafts with a 1500 unit. Look at fitting a Dolomite or Marina unit, this will alaso give you a bigger choice of ratios.
With a light car you may just get away with a 1300 small crank engine, but you will need a 4.11 diff to make the car driveable.
Watch for clutch release and exhaust issues. An 1147 engine will be easier to sort the exhaust for.
All the 800 to 1500 engines share the same block dimensions, but the bhp and torque figures vary somewhat.
Generally the best engines are small crank 1300 as they have an extra 5bhp in the bottom end above a large crank version, and the 1500 with lots of torque. If you've got a 948 back axle I would guarantee you will break rear halfshafts with a 1500 unit. Look at fitting a Dolomite or Marina unit, this will alaso give you a bigger choice of ratios.
With a light car you may just get away with a 1300 small crank engine, but you will need a 4.11 diff to make the car driveable.
Watch for clutch release and exhaust issues. An 1147 engine will be easier to sort the exhaust for.
Thanks, i have various axle options, i had bracketed up a Ford escort axle years ago to fit with an LSD and 1500 Ford pre x-flow but have now decided to go the more original looking route. The last engine in the car i am told was a Dolomite engine so maybe the axle in it has been `sorted`.Which engine prefix would have the better crank in it?........Martin
The standard diff. will be fine for anything you can get out of a non-race Triumph SC engine.
The standard Mk IV/1500 rear end won't give you any worries either - it's only the earlier fixed spring cars that can experience excessive negative camber and a sudden flick to positive camber and this only happens if you're driving like a t
t, enter a corner far too fast and lift off mid-corner. The later cars swing spring (or Mk 2/3 GT6 Rotoflex rear-ended cars) don't suffer from this handling 'feature'.
And I believe ALL 1300 Spitfires produce the exact same power - the only differences are the weight of the crank (fractionally lighter in Mk 3 cars) and this only affects how quickly the engine will spin up/weight your dragging around. Again this is only a fractional difference and having the timing off by 1 degree with have as much if not more impact on performance.
From memory the Mk3 engine is often quoted as being more powerful but it isn't - the way BHP was measured/recorded changed between Spitfire Mk3 and Mk IV models with the new system always coming out lower than the old.
The standard Mk IV/1500 rear end won't give you any worries either - it's only the earlier fixed spring cars that can experience excessive negative camber and a sudden flick to positive camber and this only happens if you're driving like a t
t, enter a corner far too fast and lift off mid-corner. The later cars swing spring (or Mk 2/3 GT6 Rotoflex rear-ended cars) don't suffer from this handling 'feature'.And I believe ALL 1300 Spitfires produce the exact same power - the only differences are the weight of the crank (fractionally lighter in Mk 3 cars) and this only affects how quickly the engine will spin up/weight your dragging around. Again this is only a fractional difference and having the timing off by 1 degree with have as much if not more impact on performance.
From memory the Mk3 engine is often quoted as being more powerful but it isn't - the way BHP was measured/recorded changed between Spitfire Mk3 and Mk IV models with the new system always coming out lower than the old.
There are various 1300 Spitfire engines, from 48bhp to 75bhp. However the 75bhp (small crank 25-65-65-25 cam) is gross, and equates to 68bhp net. The best large crank bhp is 63 (exactly the same except for the large crank). Later UK spec engines had a 18-58-58-18 cam but with a large valve head, and were quoted at 61bhp. It appears that the large crank sucks 5bhp of power, and the bearings are far more prone to premature wear.
For long life and power stick with small crank, prefixed GE, FD, RD and RF.
For long life and power stick with small crank, prefixed GE, FD, RD and RF.
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