Marking out where to cut the holes in a TB filter back plate?

[Tony C]

I was thinking about bolting the TB's in position and using my 45mm Q Max cutter on four pieces of gash aluminium and then positioning those four separate pieces accurately on the end of each TB somehow - blue tack, contact adhesive???

 

Then position the blank filter back plate over the end of the TB's and gash pieces, in the position required for best clearance from everything and/or centred on the TB's.

 

Contact adhesive on the back plate will stick the gash pieces to it. Then release the gash pieces from the ends of the TB's.

 

I now have a really accurate template for the Q Max cutter on the filter back plate.

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I'm thinking about the inherent inaccuracies with merely marking out the positions of the holes on the filter back plate by transferring the measurements - it doesn't matter how accurate I am, the chances of all four holes being in exactly the correct position is remote - from previous experience of similar projects.

 

Any experience, bright ideas or advice gratefully received

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

[DaveMorris]

I've got a similar problem with needing a backplate for a filter on a pair of 45 Webers.

 

I've used graph paper to transfer across from a base template and then used these coordinates to put onto CAD.

 

Needed to move the pairs apart by 4mm - did so on system, printed off, mounted on card (done) and checked that it fits (or at least that's the plan tomorrow),

 

Dave

 

X-flow(er) powered

[Paul Deslandes]

Template drawing on Jenvey website or press stiff white card against TBs or carbs, marking with soft pencil first. If you're using TBs on Vx engine with standard Caterham Weber carb manifold, I found that the angle of the backplate had to be tilted up at the front end a bit to compensate for the engine being lower at the front. A long good quality steel rule helps too.

 

Remember, measure twice, cut once!

 

 

[Graham Perry]

Just done this and marked the holes on the new roughly shaped plate from the back plate off of a K&N filter. It was then just a case of measuring the distance between the first set of TB's and the second and then doing it again. Sent it to a mates engineering workshop who punched it out for me. Worked a treat.

 

What I didn't do though was shape the outer profile of the home made backplate until this was done and securely in place so that the airbox itself could be positioned accurately to go though the hole in the bonnet. Once we had positioned this to our satisfaction we then cut the main shape of the backplate based upon this.