Carb's

[schoare1]

I've just got twin 45's for my 2l pinto westie, it looks fairly obvious that with the air filters on them I'll have to cut a hole in the body.  

Question's this raise's are - is this avoidable? Can you put thinner filters on them (without effecting the air supply)? Could you put a bulge in the body with a mesh screen (how difficult would this be)?

Thanks scott

[Andrew]

Westfield supply, for S.V.A reasons, I presume, one thin filter and one thick. They fit under the bonnet without cutting a hole, though I would think it can't be the ideal configuration.

 I've run this set up since my sva in March, and haven't had any problems.

[Mark Stanton]

That would be fine to get through SVA - but for an optimum balance to carbs equal depth filters (Hence bonnet hole) would be better - the shallower depth filters are o.k up to about 150BHP  or on 40DCOE's if you have 45's or more BHP then go for the deeper filters.        

[Andrew]

Yes, I didn't really understand why they (Westfield) didn't just supply two thin filters, at least the two carbs would be strangled by the same amount!,

     I am planning at some time to cut a hole and fit deeper filters.

[Ian]

I built mine about 4 years ago, and also wanted to avoid cutting a hole in the bonnet. The Westfield supplied manifold is about 3" long, and raises the carbs above the top of the chassis. This meant that the inlets were very close to the bonnet.

Burtons sell a 30mm inlet manifold, which (together with some 13mm inlet trumpets, and a 30mm K&N filter), all fits inside the top chassis rail, and hence well inside the bonnet.

My engine spec is pretty basic (130 HP), but removing the filters made no difference on a rolling road, so they obviously aren't restrictive.

Problems with it are:

-  The carbs then suck hot air, which reduces the power a bit, and gives noticable rough running when stuck in traffic on a hot day.

-  The 'off the shelf' Weber throttle linkage doesn't fit with this manifold, but you can modify the top mount one to work.

-  Very short inlet manifolds are reputed to reduce the power outlet below about 8000 RPM(!

As far as I can remember from the SVA manual, there is no problem with air filters sticking through the bonnet, as long as they're rounded. K&Ns would be no good, but foam 'sausage' filters (pipercross?) would be ideal.

Ian