Air filter

[gary.price]

Hello

Ive got a mgb engined marlin. Iv just had the engine rebuilt the car came with no air filters.
Im wandering what i can do for a filter. Will them pancakes fit?
I tried making a box out of alloy but looked really bad and didnt work tbh.
Filter paper restricts it to much. Was told just to leave the mesh on iv fitted and worry about years to come.
Seems wrong to me tho as i trial it. and summer will soon be here with dust
I tried making a foam 1 but its to restrictive aswell.

Kind regards steven

[gary.price]

Re: Air filter

Some pictures of my problem, Dont no it they will come out.

[stevejgreen]

Re: Air filter

You can gain a little extra space by thinning down the spacers between the carbs and manifold. This should give you about 10mm extra clearance. This is not so easy with an MGB setup as it moves the heatshield nearer the manifold and this carries the throtte cable fixing point. Not insurmoutable though.
After several attemps (I didnt want to cut the side louvred panel) I have ended up using a pair of short ram pipes. I occasionally worry about dust and dirt ingress and have stretched fine mesh material over them.
If I can find a pic I will post later.

[gary.price]

Re: Air filter

Hi thanks for replying. A picture would be great. So you dont have a filter as such then?

[lil_red_roadster]

Re: Air filter

If you're happy to cut the louvres then you can fit something nice & big...like a Piper air box. If cutting the bonnet sides is a no-no then slimming down the spacers was the factory recommended route (thin to 0.25" iirc)...as Steve says this will involve cutting the heat-shield as well (beware - asbestos) and you will have to work hard not to foul the throttle linkage on the manifold, so some gentle dressing with Mr Angle Grinder may be called for. All in all it's doable but painful...
Slim pancakes will also fit (just)...but the airflow is pretty poor.
If you have the time & skill you could always make up a narrow airbox with ducting to a remote filter...the pic below shows my "prototype" attempt...which worked up to a point but the inlet size proved too small at higher speeds & eventually I reverted to a single HS6 for simplicity.
dscf0255.jpg

[gary.price]

Re: Air filter

That looks really tidy. I was gonna change to single carb but my dad dosent want me to. What have you used for a manifold cause the marina 1 i have has the exhaust on it with a single pipe. Cutting the bonnet and louvres is a no go for me really as its a off roader dirt and muck will be on it. I tried mounting to 25mm 2 gang socket boxes, so im thinking make something out of that or try and squeeze some pancakes on. Suppose the side could be spaced out abit. I need maxium power from this car as the hills are steep trailing.

Thanks

[lil_red_roadster]

Re: Air filter

The setup above was a Marina 1.8 with Marina TC manifolds...which are almost identical to MGB (separate inlet/exhaust manifolds)...and a bodged up MGB 2-1 downpipe plumbed into to Marlin silencer.
Edited to add...from a simplicity & reliability perspective a single carb offers much...and power won't be down that much on twins. If I were trialling a B'series I'd seriously consider a single carb on bespoke inlet manifold, allied with the MGB/TC exhaust manifold & suitable exhaust. Maniflow can supply a decent inlet (at suitable cost).

[stevejgreen]

Re: Air filter

I would have thought a good start in getting more power would be to use an extractor (3-2-1) type manifold. But AFAIK the MGB extractors exit lower than a standard Marina so ground clearance issues will loom large. The standard Marina 1.8TC manifold is 3-2, and assuming you have a side exhaust the 2-1 section of the exhaust was a Marlin special with some pretty tight bends.
Any mods you make will have to meet Class rules for the Marlin. Worth checking with the Trials experts before making too many mods.

[gary.price]

Re: Air filter

I only want to fit a air filter lol

[lil_red_roadster]

Re: Air filter

...and therein lies the joy of our hobby...one thing leads inexorably (and not always logically) to another...or as Buzz Lightyear might say "...to insolvency & beyond..."

[gary.price]

Re: Air filter

At least your all decent people

[happyferret]

Re: Air filter

Seconded. Thank you to all that offered advice to Steven on this. I have airflow problems with the thin pancake fitted to my Webber/Fiat DOHC. The suggestions here are much appreciated.
Tom.

[AndrewKB]

Re: Air filter

I, and others, have always assumed that thinning-down the spacers between carbs and manifold is one of the contributory factors to twin SU B-Series-engined Marlins always suffering badly from over-heating and fuel vapourisation. Pancake filters work - sort-of - but they're c**p. I think that cutting-open the bonnet sides and fitting a decent size Piper or K&N is the only really satisfactory solution. Did I do it myself? Of course not! I staggered-on with pancake filters until deciding to ditch the B-Series.

[gary.price]

Re: Air filter

For the cooling my car only came with a electric fan, i borrowed a metal mgb 1 from my uncle and decided it was good and bought 1 myself, and have also fitted a second heater matrix from a old sereis 3 land rover. Dosent over heat atall now. But it is still winter!!