G'day. Have a couple of questions about jet sizing and which air cleaner I need to buy for my MK1 850.

The motor is an 850 which is being fully reco'd with new pistons 40 thou oversize and the head has been refurbed to suit unleaded. When I got the car, it was fitted with a pair of mis matched 1 1/4" SU's and a set of extractors.

To simplify things, I'm going to fit a single 1 1/2 SU which will be bolted to a water heated alloy inlet manifold (part number C-AHT770) and I think the right set of extractors are part number C-STR816. The carby I'm using is one off a Mini but no idea what motor it came off and it is being reco'd.

I need some help with:

1/. What size jet does the carby need?

2/. Which air cleaner would be best? The carby will be bolted to manifold using a 13mm alloy spacer. As far as I know, my options are a K&N type (part 56-9320), a pancake type (part PF102A) or perhaps a Ramflo (part RF3035PS). I've read that the K&N might not be the best one for the little 850.

3/. Am I looking at the right extractors?

Thanks for your help.

Rocky

The auto 850 minis in the UK used an HS4 with M / H6
https://www.7ent.com/pages/articles-tec ... eedle.html

You can also use a plastic or metal factory air filter housing off an automatic / clubman

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Thanks Timmy - so an M-H6 with a blue spring is the go.

I'll let the bloke who is refurbing the carby know.

Don't use Ramflo filters without oil in the foam! Prematurely wore out 2 engines that way.

I know it doesn't look cool, but I'd recommend Timmy's suggestion of using a standard paper air filter - they obviously work.

Also suggest getting opinions about not running hot water through the inlet manifold. The setup is more suited to colder climates and is not normally needed in Australia; combustion works better with cold, dense air going into the mix.

Just checking.... you do realise that M and H6 are two different needles??

Cheers, Ian

Ian,

No - I didn't know they are different. Which one do you suggest?

Thanks, Rocky

Thanks for the info Bill.

The bloke who is rebuilding the engine has told me to not bother with hooking up the manifold and agrees with you about not needing it. I mentioned the manifold so you blokes would know what my setup is going to be.

With the paper air filter - is this the original factory air cleaner?

Cheers, Rocky

The original paper filter goes inside the factory housing. They have an alloy elbow that bolts to the carb and the housing sits on top like this

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M is very slightly leaner than H6, but not much in it.