Everyone's been talking about do this, do that but the first thing I think you need to understand the characteristics of the engine and what you want to achieve before you go and throw loads of money at it. For example do you have a specific bhp figure that you want to achieve or do you want loads of torque and a reliable unit? Engine building can bleed your wallet dry, remember the law of diminishing returns!!!
The 1500 engine isn't a high revving engine, it's a low rev torquey unit, the max power you can get from it is about 120 - 130 bhp reliably. If you go revving the balls off of it then you'll just blow it up. I have had a number of Midget 1500's (same engine) which I have tuned up to 100 bhp and have never had a problem with reliability but then again I never rev any of my 1500 engines over 5500.
The best thing you can do with a 1500 engine is to maximise air in and out of it before going into balancing etc, so better manifold, better air filters etc... then take it from there.
I'm 'de-bumpering' and overhaulling the suspension on my midget 1500 at the moment but the engine in it has the following spec.
- K&N air filters (with a cold air feed)
- 4-2-1 Exhaust, maniflow 1 5/8" exhaust system
- SU's, not the waxstat type, richer needles (I can't remember what) I also filed the edge of the butterfly to help airflow.
- Electronic Ignition (magnatronic)
- Oil cooler, I don't have a thermostat
- Re-cored radiator
- Lightened flywheel
- Fully Balanced internals
- Uprated con rod bolts with polished rods
- Fast road camshaft
- Big inlet valves and standard size exhaust valves
- Flowed head
- I think I put TR6 pistons in it, but that required some extra work.
- Plus a panhard rod and anti tramp bars.
I get about 100bhp, I think, but I've never had it on a rolling road. Even with RSJs for bumpers it got to 60 in around 7 seconds.
When I built it I followed this article, it's a wealth of information.
http://www.totallytriumph.net/spitfire/ ... ding.shtml
Ultimately I think they are good engines, most problems are easy to resolve and spares are quite plentiful. If you understand its limitations then you'll end up with a good reliable torquy unit, which if you're rallying it will probably be really good. MG guys successfully race them in the MGOC championship.
Good luck and keep us posted on the progress.
Edit: found a photo of it at Goodwood!!