On my PP motor ia was wondering if anybody had a set of plans for a good air box the one i made was to restrictive it had 4 2 inch intake holes but the top i think was to close to the venturi but hood cleAarenc is close in a second gen

 

hmmm, you have been overwhelmed with responses.

I made up one from scratch for my 48ida weber mainly for reducing induction noise, but with a little ducting it would have done a great job of sourcing cold air.

I used a K&N filter base and cut a flat sheet of 3mm or so aluminium to be the same shape as the K&N base, then used alloy rhs to fit it into the base. I carefully measured the height to the bonnet and made a number of cardboard mock ups working until it just cleared the bonnet, then bent up a strip of alloy to form a box section to go around it and did a flat sheet for the top. I got a 4" alloy tube and crushed it down to an oval shape the same height as the side and had a talented relative mig it all together.

When dummy-ing it up, I put little lengths of blu-tac to guage just how close the bonnet was getting... it got close!

I do think it was probably restrictive, so a second 4" would have been desirable, but there was nowhere to source the air from (right hand drive rx2... there is **** everywhere!).

A plan might not really help, as it gets down to just how much space you have to play with - I had spacer blocks under my carb, increasing inlet length, but requiring a shorter airbox. I used the foam "sock" filters that fit over the trumpet, but these are far from ideal as the spring that holds them open spoils airflow.
A problem for you is just where will you have your filter - ideally you need as much filtering surface as possible, and as little ducting as possible, running as straight as possible. Dont have the ducting too low or it may collect a gut full of debris or water.
I'd ditch the 4 2" ducts and go 2 4" ducts, oval shaped if necesary. Also, use thick alloy, at least for the base, to try and reduce the radiated heat.
On my current project I am just going to cut a hole in the bonnet and hang the K&N out...