well...bad news for me..ive hit a problem so im after some help if possible.
as far as i know the design of my cold air box/plemium is pritty close to what link automotive make but im worid about the size of pipe to use as my car isnt running that good at present and i think that the air pipe is two small.
im using two inch pipe witch i thourght was big enough but it seems not to be as when ive got it all on ,the car suffers
from what i can only describe as lag.
the car gose then hits a flat spot under 2000rpm then it hits 3 and gose ok..
when i remove the pipe everything gose good no lag.
i removed the whole unit and ran it with no filter at all just around the block ...and
holly crap...it felt much quicker to me and a lot more pull too.
guse my box isent that good after all although it looks good
im after any help here regarding the size of cold air pipe i should use as i dont want to
stop with this project alltogether???\
if i cant fix it im going to try to use just ram pipes and sock filters as it seemed t run so much better with no air filter although she will be then just sucking hot air from the exhurst???im running out of idears....
any help would be great..

minifreak1(brien)

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started a new project...there goes all my free time....

you need that hot air to get her running on cold days

Have been reading Vizards yellow book lately and it seems as well as cold air and possible ramed air (although negilable) there is also inertia ramming or something similar which involved making the ram pipes / air intake longer in order to increase torque.

Anyway according to Vizard K&N brought out a torque master thing which looked very similar to what you have made. They stopped making them because they made it hard to set up the carburettor correctly. They were apparantly effective and it could be used to tame a lumpy cam and give you back some low down power without seriously effecting inlet flows at high revs.

It sounded a really cool idea, so just thinking you might be experiencing the 'setup problems'

The torque master strengthened air supply down low with a little cost in flow higher up so maybe the carb is running lean at the lower revs.

added to which you have cold air which means that you are getting more air into the cylinders which also means you will need richer jets.

also did you run it for a while and let it warm up because cold air I AFAIK can result in rough running until the engine gets to operating temperatures.

A whole lot of theorizing on my part but it may be helpful.

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

Try a bigger pipe. It does sound like you aren't getting enough air in the thing.

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Jonathan
http://photobucket.com/albums/y64/FatMaserati/

I would think you are getting enough air but not enough fuel. But it could be the way the air is flowing that is stuffing things up.

The ram effect from the long pipe acts like a ram tube and the pipe has to be the right length to get the pulse right and it is very hard to work out the right length. At some revs the pressure wave will be reaching the valve when it is open and at some revs it will be reaching the valve when it is closed. It is very hard to get it right for all revs.

seriously,,,a "Decent" air box for a weber/dellorto/solex type carby needs to be quite large & with "AMPLE" sized tubing feeding it,,,it will be bulky & obtrusive, fill quite a large space/area & then you`ll need to sort the jets etc to "tune" it to suit & will also nbeed some "SPILL" holes to help it not "ram air" in.

your plenum thing is just too small for that sized & length of pipe , you`re sort of creating something for the weber to suck against, making it harder for the air to "jump in",,,

as you have found out,,,it runs better with nothing on there,,,well,,,simply """Ease of entry of avaliable air""" is what`s happening without the filter,,,& it`s Not happening in your case with that plenum thing.

my race set up simply pipes huge diam pipe "TOWARDS" the rather large air cleaner that i have,,,,& it`s piped from the front of the engine bay,,,that`s it,,,some of the "gurus" & "race legends" in the UK run a rather complicated air box thing as i described above, but i`ve tested my set up & it works a treat, it`s easy, cost effective & is also easy to remove,,,i don`t like spending huge somes of time & money when just a piece of large diam pipe works pretty well just as good, ,,,it isn`t "AS" good i`m sure , because the air i`m getting isn`t quite as "STABLE" as the good expensive Race air boxes allow, but is well good enough for over 122hp & 122 MPH

"KISS",,,,Keep It Simple Stupid

no offence, but when i saw your post & pics of your air box i was waiting for this exact thread to arrive,,,

there`s simply no power gain to be needed at idle or in traffic right???,,,so you really only "need" cold air to the carb when you`re flogging it right???,,,so just pipe up some huge diam pipe from the grille to """AROUND""" the weber inlet/filter area, job done!!!,,,probly still need a bit of jet "tuning" anyways, but way way better propersition that what you have, Ram airing it will not work & that`s "SORT OF" what`s trying to happen also with your setup.


You did have a good go at it tho & i applaude you for your efforts,,,just feed the thing with way bigger pipe & use a way bigger air plenum (as you call it) & don`t allow it to Ram air in & you may find better results, but i`m thinking that you`ll still probly have some "tuning" to do anyways to suit whatever you end up with

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.