Lightened Flywheels

[Chris KC]

Unless I'm much mistaken the Accuspark and Bosch units both have mechanical advance weights just like the DK4A, at starting they are fully retarded and will advance (automatically) as engine speed increases and throws the bob weights out. No need to adjust anything but the basic setting, which I suggest should be the same as the DK4A i.e. TDC

[dickie65]

Happy New Year,
If you lighten the flywheel / coverplate and balance it all you need to index the parts,
Timing Marks do this on the standard set up.
I have never used a strobe on Seven,

My arms are not long enough and contrary to popular rumours not all people living in Cornwall have the required Two Heads to look at a strobe inside the car while adjusting the dizzy under the bonnet.

I only use the timing marks when assembling the engine. ( the following is fine for a 1933/34 coil engine manual advance)
I use a thumb over no 1 spark plug hole and rock the car back and forwards in gear to make sure its on compression stroke.
Check piston is about at TDC. I then set dizzy to just open points. Bulb and test wire will help.
This is usually good enough to get the engine to start, I then manually adjust the dizzy till I get the fastest tickover.
Take car for a drive and adjust further from there.
On the Type 65 you will never be able to see the timing marks with the engine in the car, its only just possible to get the flywheel cover off in situ.

Cheers Richard

[Bob Culver]

The topic of ignition advance and all the confusion associated manual and auto instructions,  the various auto advance ranges, both original and as modified or worn, and the bum and oft repeated info in Ruby 1 book, recurs. Covered in post of 13.11.17.
TDC static is not ideal for all auto. 
 
In the days when all cars were provided with accessory crank handles, static timing up to 10 deg was quite normal.

The requirements of the racing/motorway fraternity are for absolute max power at high rpm, usually with robust cranks, and these often considered expendable.
 
The requirement for sedately driven stock engines, with rpm seldom or never attaining 4,000 rpm, and often with an original crank is somewhat different. The minimum advance for reasonable performance and tolerable smoothness should be used.
 
The various opinions expressed need to be read with thought of the application.
 
Do not judge power from noise. Without a test hill and careful allowance for engine warm up etc, the tendency to judge power from engine noise makes it difficult to compare settings.
 
Manual advance is very instructive. I would not deliberately knobble, although it can be retained as an override (or one made using choke or mower type cable).

[Chris KC]

I don't disagree Bob, each engine is different. TDC is a good (safe) starting point for auto advance cars but fine tuning must be done on the road.

[Dave Mann]

    I got fed up scrabbling about under the dash, after removing the starter, to see the timing mark, and ended up with a pointer on the carburettor side of the camshaft pulley and a paint mark on the pulley. I just have to remember to redo the paint mark if I have the pulley off.

[Malcolm Parker]

I have had various Austin 7 engines, all with a similar state of tune (ie raised comp ratio, flattened cam followers, SU carb), some have had lightened flywheels and some have not.   When using an original 2 brg crank, I was advised by an experienced Austin 7 engine builder to have the flywheel lightened slightly at the rim as it reduced the stress on the crank.   It certainly makes the engine pick up quicker but can be a disadvantage when pulling up hills, especially with a 3-speed box.
My Ulster has a Phoenix type crank which is heavy in itself and a standard flywheel.  The engine does not feel particularly lively but it will pull like a train and takes hills in its stride.   In my part of North Yorkshire which is quite hilly I think on balance I prefer the hill-climbing ability rather than having a lively revvy engine.   Going up a main road hill at 50mph in top is more relaxing than screaming up in 2nd at 5000rpm.  As with many things relating to Austin 7's, a lot depends on what you want to use the car for.
As an aside, the spare engine I am building at present will have the heavy Phoenix type crank but the flywheel will be lightened slightly.

[AustinWood]

Timing scatter is clearly visible with a strobe on the fan pulley. A mark such as Dave suggests makes it easier too. No need to access the flywheel. Care is needed as the fan may well appear stationary.
I have a 3 speed box with the flywheel lightened as far as possible on the rim. This combined with the Andes 2nd gear makes hill climbing at 30-40 mph very easy, especially here in the Scottish Borders. The lightened flywheel also helps with quicker gear changes into top on hills.
However, having experienced Malcolm's Yorkshire hills, this set up doesn't work so well there. I am often reduced to 1st gear where the standard 2nd would still work. End up screaming up in 1st and struggling to overtake bicycles! On one occasion the combination of gravity feed and incline caused us to run out of petrol alongside a bicycle. Very embarrassing!