mg midget engine 1500 swap ??

[bmcecosse]

The manifold can take either the HIF 38 or the 44. Don't worry about it!

[timetraveller]

hi bmcecosse

if your running this set up what size is your carb is it a 1.5" or a 1.3/4 inch
or doesnt it matter ???
if this is a tried and tested method then i think
im gonna give this set up a go but dont want to buy the wrong bits

what are the gains your getting from this modification ????

its sort of half of a stage one tuning kit for a mini i suppose

thanks
neil

[GeorgeHurst]

hi neil,
indeed, many of the alloy inlets have a 1.75" bore (HIF44) but this is absolutely fine for a 1.5" carb (HIF38). The only time it would cause an issue is if using 1.75"carb on 1.5" manifold. Both HIF38 an HIF44 have the same mountings so inlet will be fine either way.
I'm not exactly sure of the power gain but I guess somewhere in the region of about 10bhp gain, making the standard 48bhp ~60hp. I'd say this is definitely the cheapest + easiest route to more power, the next step up being a 1275 midget/marina/ital unit, then a tuned 1275, and then an engine swap, i.e midget 1500, fiat twin cam etc etc.

[bmcecosse]

Mine is HIF 38 with AAA needle. Goes like stink!

[Declan_Burns]

hi george

according to the info i found a HIF38 carb has a 1.5" bore and are from a mini 1000

your pointing me to a 1.3/4 inlet manifold

it all doesnt seem to add up

neil

I made up a carb spacer which is filed conical on mine (HIF38) to get a better flow using that manifold-no sharp edges.
Regards
Declan

[bmcecosse]

The 'sharp edges' upwards to a larger bore are not harmful - the air flow makes it's own 'taper' - by doing so with a spacer you may actually be hampering the flow !

[timetraveller]

so to recap ive got my eye on the following

mini/metro performance water heated/cooled inlet manifold
lcb exhaust manifold
HIF 38 SU carb (requires AAA needle if not fitted)
12G940 unleaded head
gasket set

can anyone foresee any problems

neil

[GeorgeHurst]

don't worry about the head being unleaded or not, you can use unleaded regardless, just set the exhaust valve gaps to 15 thou and the inlets to 12thou (I think!).
With the exhaust you would be best running the LCB into a big bore pipe and straight through silencer to get the most out of the engine, power will be significantly reduced using the standard exhaust pipe. JLH Morris Minors do exhaust sections and cheap silencers that you can make your own system up out of, in mild or stainless steel.

Oh, the one thing about the 12G940 head is that sometimes, but not always, the exhaust valve seats will need sinking a little bit else the valve can foul the block. There are numerous threads regarding this, including one started by me which goes throught the measurements needed to calculate if the head you have is ok or not.

Other than that I think it is is a simple bolt on job

[bmcecosse]

So called 'unleaded' heads tend to be expensive -as George says - just use an earlier head - it will be fine. And you MUST check there is 320 thou clearance for the exhaust valves.........

[Bazzalucas]

When you say, 'big bore" exhaust, exactly what diameter would that be?

[GeorgeHurst]

Jonathon from JLH once told me 1.75" is dood up to 1300, then you want to move up to 2", so for this application 1.75" is what you are after. I'm using 1.75" stainless for my tuned 1275 set up

[hotrodder13]

im using 1.75 on my 1293 and only 1 silencer and i got to say its stupidly loud should have put 2 on but it does look good at the back of the car

[callyspoy]

Hi,
If you find that the L.C.B is too expensive, a cheaper option is to buy a post-74 mini 850/1000 inlet/outlet manifold combo. The Minor exhaust will bolt straight on to it and although it may be more restricted than an L.C.B, it does work (I had it fitted briefly to a 1275 and it was ok).
It was designed with the 1 1/2 carb anyway. Apparently this set up does work better if you already have a stainless exhaust.
The mini has a 2-stud diagonal fitment but i know that the 4-stud carb does fit onto it as well. The part number is 12G 787, which is cast onto the exhaust part of the manifold.

Regards callyspoys Dad.

[GeorgeHurst]

Indeed, another thing to use is an Ital manifold, which is a two branch cast manifold, if you can weld you can then make a 2 branch downpipe to connect to your exhaust pipe. Have a search for 'vortex exhaust' on this forum and you will find pictures of this made by linearaudio.

[bmcecosse]

Mine is a Mini Cooper manifold - which according to Vizard works surprisingly well - modified to pass between engine and chassis leg - and then curls round under the leg to a large bore Cooper S silencer in the normal place.

[timetraveller]

hi
i managed to get and lcb exhaust manifold for £17 today but it looks too long and will need to be cut and the y pice fitted then pass it through the chassis leg and mate it to a 1.75 big bore system.....so any advice on silencer boxes as i still want it to look pretty stock (or should i say i dont want a big sports pipe sticking out the back) ???

also managed to get my hands on a carb,inlet manifold and a mini head so the parts are flying in.....!!!!!!

the inlet manifold i bought can be piped into the water for heating/cooling......is this a necessity or can it be left???

theres gonna be a lot of questions over the next couple of weeks

[GeorgeHurst]

nice one that's quick work! and a bargain on the LCB!
As to the silencer, I would look out a jetex one, JLH sell these, they are totally free flowing and can be placed under the car so you don't get the 'sporty back box' look. Or look for a Mini RC40 exhaust system, they are relatively quiet, but with a sporty note, and not too steep.
I think most people don't use the water heated bit on the manifold as it can heat the fuel air mixture too much and make it to vapourous for good combustion (I think!)... for what it's worth I won't be using the water heated bit on my set up.

p.s. I have a 2" mini exhaust system surplus to requirement at the moment... it consists of an oval silencer box and a small tubular silencer and then a load of 2" pipe. Surface rust but very sound, would clean up well with a wire brush. I was going to save it for a future project but if you wanted to give me £25 for it, it would probably be better served going toward my current restoration! PM me if your interested.

Cheers
George

[bmcecosse]

I don't use the water heating - I want the mixture going in the engine as cold and dense as possible!

[Alex'n'Ane]

The car in the link is mine

hi and thanks for that
looks like a squeeze in there
which side is the exhaust manifold on.....under the carbs ??
any cooling problems ??
using original engine and gearbox mounts ??
propshaft shortened ??
is it running a different rear axle ??
thanks
neil

The engine imparticular is a dolomite 1500 but same engine and i believe gearbox. She is/was running a dolomite rear axle (IMO a good set-up as its same width as minor and has same pcd as marina front uprights/discs.) She was running a standard two piece dolly prop. However this meant the engine was mounted further forward than necessary, hence the side mounted rad. She is currently in the process of being removed, ready to be transplanted into a different minor, in which she will have a shortened prop (to minor rear axle), allowing for a standard front mounted radiator. I cant comment on cooling as i've never had her on the road. The front mounts have be made out of standard minor mounts with a small bracket welded to them, and its a standard gearbox cross-member just with different rubber mounts. If you are still considering this conversion send us a pm and can give you any more info (and parts) you may need.

[MarkyB]

The nice thing about the 1275 is it's just an nuts and bolts job, a piece of urine as they say.
I'm not even sure the 1500 was a good engine even back then, once you get into having to modify just about everything to make an engine fit then it's time to take a step back and decide how much bang for your buck you will get for all that work.

For much the same amount of work you can put a lighter, more powerful engine in.
This is why Fiat twin cams and Zetecs are more common, you get much more bang for your buck, even if that buck is time, not money.