The story thus far: Soon to be former grad student Dennis Wilson asks
about engine options for his Spitfire powered Midget. Scott Fisher, a
forthright Defender of the Octagon, tries to convince him to go with a
Triumph 1500 motor. And I, for another, will echo that sentiment. Hey,
maybe I should convince him that this 1147 motor in the red Spitfire I have
is the hot ticket....
Scott cautions:
Do note that the high-compression cylinder head means that you are
going to have vastly reduced valve lift before your valves meet your
pistons. Be sure to measure carefully or do a test assembly before
you fire it up.
I wouldn't worry TOO much about this. The Spitfire 1500 Competition prep
booklet has this as the first sentence in the section on head modification:
Starting with a stock 1500 head, resurface 0.200.
What this means to you is that with a streetable cam, say 280 degrees of
duration, maybe 0.39 to 0.40 lift at the valve, the valves and pistons
should not meet.
Scott also says:
A pair of 40DCOE Webers with appropriately small chokes for high intake
velocity will be a lot of fun.
Actually one can get single carb or dual carb manifolds for this head, the
single version might be enough. I'm not sure what the clearance for a pair
of DCOEs, stacks and filters might be in the Midget. My Spitfire has a DCOE
(Chris, it only has two intake ports, no place to put two carbs) on it at the
moment, and MY 1147 is faster than my friend's 1147, even though his is in a
lighter Mark 1, not a 1500 body. As I've said before, putting some number
of Webers or SKs on the car can change power by -10 to +15% or so. Any day
now I'll get the mighty 1147 Spit on a dyno!
Oh, and *do* fit an oil cooler
Yes, a good idea. I'll just take this opportunity to put a blatant commercial
into an otherwise innocuous post and say that The Fat Chance Garage sells
Weber bits and Earl's plumbing. Drop me a line for a quote. Now, back to
your regularly scheduled mailing list.
In summary, a 1500 motor running maybe 9.5 compression, a moderate cam with
improved intake and exhaust can put out maybe 85 bhp at the flywheel. I hope
to know more later this year when I start in on my own 1500 motor.
mjb.
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