not french... airbox enquiry

[jgra1]

chaps, I am needing to modify an airbox made for my camper by a friend, due to me fitting twin carbs. The van is mid-engined (almost ) so there is major restriction on room..

Are there any basic rules of thumb, concerning airbox size (litres) and minimum extents (this box is very shallow, although reasonably long and deep. i.e. its about 18 inches by 7 inches, but only 1/2 inch across..

engine is 1725cc Old british thing...


does that make sense?

realise its a fairly daft question.

[bxbodger]

Rootes group engine?? Basically it just needs to be as big as possible-it's main function really is to keep the incoming air cool because of the confined space. How is the filter arranged? 1/2 inch is pretty narrow- my Triumph has K&Ns on twin Strombergs- they sound great and make it pokier but, because they only just fit, when it gets really hot under there they don't like it!! The standard Vitesse air box is pretty much as you describe only about an inch wide, with a long cool air intake pipe. On the standar box the filter sits inside but at 1/2 inch will you have to put the filter elsewhere?What carbs are you using-if it is Rootes (I can't think of any other English 1725 engines..) are you using webers with a holbay head??

-and why not stick some pics up over on
http://popularclassics.forumcircle.com/index.php where some of us lurk with our older cars...... 8)

[jeremy]

One Commer that hasn't come to a full stop!

Sunbeam Talbot suspension albeit widened a little!

Presumably it originally had the iron head 1725 with a single carb - and now has the alloy Humber/Sunbeam/HunterGT/Singer Vogue one with the twin carb manifold. Have you managed to find an overdrive gearbox for it?

I would have thought the first priority was to make sure there were no pinch points in the airbox and that its cross section was always equal to or greater than the cross section of the carb - ie if necessary is wide and thin. I suppose you will have to place the air cleaner somewhere convenient and any opportunity to pick up cool air will be an advantage.

[jgra1]

you both know me too well!!
commer autosleeper '68


1725 full High Comp. sceptre mark 3 engine, standard commer gearbox. ( I thought of OD then couldnt quite work out the component change needed at the last section of box (plus a propshaft cut) so gave in - it was 4 years ago)


someone did say, that I ought to aim for as much 'depth' as width across the carb mouths...

I maybe have airbox @15mm depth, width across carbs are 50 mm

photos may make more sense..

at the far end of this restricted airbox lies one large powerfilter.... I have another, but adding it is no use if the airbox is restriciting me...
John