Morris Minor Owners Club

Bmc

Thanks for the advice.

Are you suggesting do nothing or just shorten the screws?

There is also a screw from the piston guide that extends into the throat of the carb.

Thanks

Pete

Shorten them if you wish - but do convince yourself then that they won't fall out.... BTW - I always radius the incoming edge of the piston to smooth the incoming air, and I heavily radius all around the intake to help minimise the vena contracta. Every little helps!

Thanks.

I'm up for anything I can do myself or that's available second hand to bring advantage but not sure about screws floating about the combustion chamber

Do you/anyone have experience of the item in the following photo?

It's shown in an MGB air filter and is a shallow profiled aluminium 'ram pipe' that offers 5% increase in air flow. The logic appears sound and it doesn't look too difficult to fabricate as I also found the dimensioned drawings.

I guess more air means more fuel means more needle?

Any advice as I'm way outside my comfort zone and in danger of getting enthusiastic ?

Pete[frame][/frame]

It's far easier to just heavily radius the intake to the carb.... There will be no 'ramming' on a standard engine ! The 5% possible air flow gain is the vena contracta..... But a standard engine won't be needing any extra air flow anyway- how often/how long do you drive with your foot 'to the floor' ? The air demands of the engine will be limited by the valve sizes/cam timing and lift - and the 6000 rpm rev limit for a 1098.... So a 1.5" carb will be fine, even without any mods..... More air flow on an SU is matched by more fuel automatically - it is an EXTREMELY clever design.... so there won't necessarily be a need for a different needle. So saying - it's unlikely to be spot-on anyway - there are always gains to be made by optimising the needle profile, and the piston spring force.

Bmc,

Thanks again.

I found a cute animation of an SU in operation so I now understand the fuel air logic you describe.

When you say 'heavily radius', do you mean take the edge off or 5mm at 45 degrees with soft edges? And I guess also open the gasket and filter plate.

If my ebay manifold would just turn up I could cut it down and work some of this lot out

Thanks

Pete

I found a cute animation of an SU in operation

Got a link for that ?

Yes - a really good radius - not just 'edge off'. I use a half round file - and then polish up with wet/dry paper etc to finish off. Yes - all other holes leading to the carb must be made larger to be well clear....

Bmc,

Thanks I'll give that a go.

I've got all the bits now but fear my enthusiasm has got the better of me as the 'bore' in the second hand manifold looks narrow. I may be wrong as I've never looked down the action end of the current one.

Are they all the same?

Casting says 2A89605

Thanks

Pete

Katy,

http://www.roversd1.nl/sd1web/carburation.html

This should be it, last item bottom right.

Pete

This is the photo of the manifold I got for £1.99 on ebay.

Are these one size fits all or do they have different internal diameters?

Thanks as ever

Pete[frame][/frame]

Just measure the hole with a ruler and compare it to the hole in the carb.[frame][/frame]
Here is an animation, shame it doesn't show the amount of mixture going in increasing.

Markyb

Thanks for the advice.

The carb I'm intent on fitting is 1.5" Hif 38 and I have a new alloy inlet manifold the right size for that.

The combined manifold that I intend to cut down "looks" to have a narrow bore, I could easily be wrong.

Hence the question, were there originally different internal diameters to manifolds to suit different A series engines?

Were Austin different from Morris?

All help appreciated as I don't want to cut down this manifold if it may be of use to someone else.

Thanks

Pete

Just measure the hole in the manifold, if it isn't 38mm you'll need to file or grind metal off until it is.
A low budget Dremel type tool may help, or a flexible drive from an electric drill maybe?

Dremel will never do it! Yes - exhaust manifolds for 1275 Marina had larger bore exhaust connection. 1275 Mini had double exit manifold - possibly/probably also fitted to Ital ???

Marky, Bmc,

Thanks for the replies.

I took an 8" disk to the manifold and have now removed the carb inlet and am left with this.

Sorry if I'm being slow but I'm still not sure from your answers.

Do all manifolds of this type (ie: exit to suit standard Morris Minor exhaust) have the same internal bore?

Thanks again.

Pete[frame][/frame]

Sorry, this is the obvious photo

Can anyone confirm if this is the standard size for 1098 exhaust manifold?

Thanks

Pete[frame][/frame]

Dremel will never do it!

What would you suggest then?

Dremel is just a toy - for model/jewellery work.... If you want/need to enlarge the holes then mounted points or carbide burrs, ideally in a die-grinder (which few of us will have) or an old electric drill will do a decent enough job. That manifold looks standard 'small bore' A series. The exhaust appears to be the standard Minor size. Later big bore manifolds have larger outlets - to the exhaust system (so won't suit a standard Minor system) - but I don't think the port holes are significantly different - may be slightly - I never bothered to check since never used such a manifold!

Bmc,

Terrific, that's just what I needed to know. I'll worry about a big valve head and LCB later.

Marky,, with regards to the Dremel, Bmc is correct, it would certainly never have the grunt to cut through the manifold. I used an 8" disk then a grinding disk on an angle grinder and think I've got a reasonable job done.

I'll fit something suitably aggressive to a drill to open the carb throat.

Thanks both for your advice.

I'm now ready to fit everything - I'll report back after the weekend.

Pete

Open the carb throat??? Do you not say you have inlet manifold of the correct size?