Hi all can any body recomend a metal grill i can use to filter air
have tried making air box with induction type filter but cant get engine to run well
seems to choke engine wont go above 4000 rpm when fitted
so looking at using airbox and fitting grills to it
trying not to poke filter out of bonnet
(2000 pinto with bike carbs )

Have a look at Jacko's archive.

Can you not mod a k+n element?

I'd use a K+N type filter. At the very least they don't kill power.
Wire mesh type filters (like the mesh covers you can get for Webers and Dollortos) actually often result in power loss and don't actually filter that well anyway.... They still let sand and grit it which'll do a hell of a lot of damage....
If it chokes @ 4000rpm it might well be the jetting, if not then the induction filter is likely to be too small a cross section for the big boy Pinto

How much space have you got between the top of the carbs and the top of the airbox on your current setup? I've heard 2/3 choke width is the bare minimum (as a very rough rule of thumb). Less than that and you'll cause a local bottleneck (strangling flow) regardless of what super-duper filter you've got upstream....

If you attach some nipples to various points on the induction system and hook them up to manometers made from some tubing and coloured water you can run the engine and see what relative vacuums you're getting and where any restrictions are occuring.... (obviously make sure when you make the manometer U big enough to prevent water being sucked into the engine....)... You could do it properly with a vaccum meter (like a Carbtune) but some clear tubing and food dye is more Locost...

hi ben sorry did not reply sooner
ive got about 32mm from carb to air box face but the box is about 100mm tall
the induction filter is big its got a 75mm outlet (took trumpets of to fit air box dont no if this is not helping)
thanks for all the other info i will give it a go this weekend
ps the car runs great with out filters

The problem with taking trumpets off is that it will prevent the airflow from being laminar within the airbox. So although it creates space, it also creates turbulence. When the airflow is turbulent you're going to need a greater space between the throat on the carbs and the airbox for a given amount of CFM airflow. You may well find that fitting cut-down trumpets (if their design allows) would improve power and flow even though it will reduce the already quite small gap....

I wouldn't ever use metal filter elements, as they don't really work as filters. The mesh things Ben mentions are poo. They filter out rocks and stones, but not a lot else. They also limit flow, and can cost power over a proper filter. A big enough airbox with a large enough space between it and the trumpets (I'd suggest a minimum of at least the diameter of the trumpets at their open end) and then as big a filter as you can get. I have one on my mini that's rated at 450 BHP! Mainly, though, as the 48 IDA only has huge filters available!
If it won't rev above 4k rpm when the filter and what have you is fitted, they aren't flowing enough air. They are strangling the carbs of air in some way.

Im using a 100mm K&N challenger air box filter as it allows plenty of space for the stock Kawasaki trumpets and loads of filtered air. It i shuge though and i dont know what it will look like when fitted yet (awaiting manifold from Boggs). If it i stoo big i know i can get a 75mm element and clips from Vision plus which is still big. Apparently the 100mm unit flows enough air to feed a 500bhp motor.

Without the trumpets i could take it down to 25 or 50mm which is still good for air flow but im not tempted to junk the trumpets for the reasons outlined above.

See this thread http://www.locostbuilders.co.uk/viewthread.php?tid=46508 which goes into some detail about trumpet design - stub stacks look a good idea in your case, a plain opening is awful and will create all kinds of problems for the reasons given by BenB.

I was looking for that thread my self recently!