Also, if you're rallying it, don't lower it, keep it standard, or dependent in the events, maybe plus 1 inch

I suggest that you get the pistons & conrods balanced too. A balanced 1500 engine runs better.

As has been said, you must cross drill the crank, as the bottom end lubrication is the biggest weakness on the 1500 engine. It was also recommended to pin the thrust washers to the main bearing caps to prevent them from moving.

An oil cooler is essential, even on a hard driven standard motor. Make sure you get one with a thermostat.

The flywheel is quite heavy and should be lightened.

Also, I have it on very good authority that it is quite beneficial to skim the block, so that the pistons are completely flush at the top of their stroke.

I have read that Terry Hurrell (of Triumphtune) used to run a tuned 1500 Spitfire as his everyday transport. It was apparently very reliable and produced 120 BHP.

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!!

Waxstat type are the red jet carbs aren't they as mines got a pair of those on

No, red jets are what you put in when you get sick of Waxstat jets, Waxstats have a little silver disc housing on the bottom, about the diameter of a 2p piece.

Steve

On a performance engine the Waxstats can tamper with your mixture settings, I think they can make the mixture too weak. They also have a poppet valve to prevent over-fuelling on the over-run, non waxstats don't have this and this opens up the chokes.

Edit: Here's a photo I prepared earlier!!

These are HS6's with Waxstat jets but are essentially the same as HS4's, you can see the valve on the butterfly.



If I can tomorrow I'll take some photos of the Midget engine, actually, thinking about it I do have to change the release bearing so I'll take some photos of it then for you.