The Filter
The original pancake air filter was never fitted to the engine due to clearance problems, and it was far too hideous to warrant cutting the bonnet.
So the intention was to fit side draught Weber's(40's), after further investigation it was decide the hassle and sheer expense was going to be unjustified for the marginal performance gains.
Luckily, K&N came up trumps with a bolt on performance filter so it was time to get out the drill and hacksaw and set about fitting it!
Firstly, it needed marking in the mounted position, it was imperative this was done right first time as a new bonnet was not an option.
Dismantling the filter allowed me to fit the bottom plate with the 2 upright bolt posts exposed, the tips of which were dotted with ink to act as a marker on contact, closing the bonnet gave me the marks indicating the proximity of the filter on the underside.
As the bonnet was not able to close all the way and the fact the lid hinges from the front the markers were adjusted 5mm forward to allow the natural angle at full closure(otherwise the hole will be slightly too far back in this case).
These 2 marks now indicate the corresponding bolt holes, these can then be drilled through using a fine drill bit.
The top plate of the filter was used to match the bolt holes to the bonnet the filter could now be drawn around in its theoretical mounted position using a marker pen this was a bit tricky as the bonnet is quite curvy but if in doubt make your final shape smaller, you can always make it bigger after!
With the filter drawn on the topside, the engine was covered with sheeting to protect it from the next stage(this is essential especially with an exposed carb choke beneath).
Using the finest(smallest) metal drill bit the arduous process of carefully drilling hundreds of fine holes was undertaken.
A jigsaw or angle grinder are not really an option here-the former will shatter the surrounding material beyond control and the latter may scorch the fibre glass and be tricky for precision.
That said- dont be tempted to use a too large drill bit, this will also cause chipping of the topside.
Once sufficient holes had been drilled, a couple were enlarged using a larger bit to create an entry point for the hacksaw blade, using the blade by hand the now perforated hole was cut without damage to the surrounding area.
Once the hole is cut, re-close the bonnet with the filter re-assembled and fitted underneath the sheet protecting the engine, this will allow you to complete the adjustment stage easily.
Using Aluminium Oxide paper, smooth and enlarge the hole as necessary, re-offering the bonnet regulary until it fits with sufficient clearance(as the filter protudes in this case).
How much clearance needed depends on how you intend to trim the hole, In our case a nice strip of self grip(v-shape) rubber was used to line the hole and make it nice and tidy. rubber trims where found at www.woolies-trims.co.uk
So the intention was to fit side draught Weber's(40's), after further investigation it was decide the hassle and sheer expense was going to be unjustified for the marginal performance gains.
Luckily, K&N came up trumps with a bolt on performance filter so it was time to get out the drill and hacksaw and set about fitting it!
Firstly, it needed marking in the mounted position, it was imperative this was done right first time as a new bonnet was not an option.
Dismantling the filter allowed me to fit the bottom plate with the 2 upright bolt posts exposed, the tips of which were dotted with ink to act as a marker on contact, closing the bonnet gave me the marks indicating the proximity of the filter on the underside.
As the bonnet was not able to close all the way and the fact the lid hinges from the front the markers were adjusted 5mm forward to allow the natural angle at full closure(otherwise the hole will be slightly too far back in this case).
These 2 marks now indicate the corresponding bolt holes, these can then be drilled through using a fine drill bit.
The top plate of the filter was used to match the bolt holes to the bonnet the filter could now be drawn around in its theoretical mounted position using a marker pen this was a bit tricky as the bonnet is quite curvy but if in doubt make your final shape smaller, you can always make it bigger after!
With the filter drawn on the topside, the engine was covered with sheeting to protect it from the next stage(this is essential especially with an exposed carb choke beneath).
Using the finest(smallest) metal drill bit the arduous process of carefully drilling hundreds of fine holes was undertaken.
A jigsaw or angle grinder are not really an option here-the former will shatter the surrounding material beyond control and the latter may scorch the fibre glass and be tricky for precision.
That said- dont be tempted to use a too large drill bit, this will also cause chipping of the topside.
Once sufficient holes had been drilled, a couple were enlarged using a larger bit to create an entry point for the hacksaw blade, using the blade by hand the now perforated hole was cut without damage to the surrounding area.
Once the hole is cut, re-close the bonnet with the filter re-assembled and fitted underneath the sheet protecting the engine, this will allow you to complete the adjustment stage easily.
Using Aluminium Oxide paper, smooth and enlarge the hole as necessary, re-offering the bonnet regulary until it fits with sufficient clearance(as the filter protudes in this case).
How much clearance needed depends on how you intend to trim the hole, In our case a nice strip of self grip(v-shape) rubber was used to line the hole and make it nice and tidy. rubber trims where found at www.woolies-trims.co.uk
