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MG Midget and Sprite Technical - engine advise

Ok guys, and dolls,

Not that the archives are empty but just to update on all info available and to please you all to put foreward your info:-)

My midget MK I with 1098 early engine is going to get the 1275 that is waiting for to much time in the shed now.

The Midget already has its 5 speed Datsun tranny and a Titan inlet with single HS6.

those 2 are mods I want to keep but the 1275 in the shed is almost original and my aim is near the 100 Bhp mark. Wat to do?

Raising volume from 1275 to +40 or + 60 overbore or maybe even 1380? Cam options? It must be drivable in trafic and city. Rockers? double adjustable chain? Head modifications? I know thats the area where the biggest gain is to be found.

Can I use the rebuild distributer or should I switch to 123 or mallory? Should I install electronic ignition? And what about exhaust?

Unleash your imagination, but... I would like to keep this job within the 2K euro job. The suspension has to be updated too so money is limited:-(

Bas
Bas Timmermans

Hi Bas
Try Peter Burgess I'm very please with the work he did for me.
Steve Deakin

Yep but sending the unit to Gb and Back will be a major part of the 2 k I have available so I am after your advise that a Dutch specialist can perform.
Bas Timmermans

where are you measuring your required 100bhp, at the wheels or at the flywheel? Big difference in specification...
David Smith

try swiftune, they got a kit, that has a nice cam, roller tip high lift rocker, adj. timing chian, springs...lifters, and oil pump for a great price....id get 21253 pistons a nice dist. the old cooper s diminsioned valves the rimflow knock offs with waisted stems (aka... penny on a stick), aluminum flywheel...get it all balanced buy vizards book, and port the head the way he discribes....and your there


http://www.swiftune.com/Product/450/sw507-highlift-kit.aspx

http://www.minimania.com/web/SUBTYPE/SearchText/CarSearch/MINI/Search/21253/Search_Inventory.cfm

http://www.minimania.com/web/SUBTYPE/SearchText/CarSearch/MINI/Search/rimflow%20valves/Search_Inventory.cfm

prop
Prop

http://www.minimania.com/web/SUBTYPE/SearchText/CarSearch/MINI/Search/rimflow%20valves/Search_Inventory.cfm


try that last link agian
Prop

okay lets try this...you will have expand to see all the valves...but oh well


prop
Prop

http://www.minimania.com/InvDetail.cfm?Item=RIMFLOW1%2E15L


Im headed to bed...it to late and was a long day


sorry

prop
Prop

Maniflow exhausts are great. be sure to read David Vizzards book
S.A. Jones

A 1330 with BV head, 276 cam, single HS6 and LCB/RC-40 will make 100bhp at the flwheel when run in; and you should see close to 90lb-ft torque with straight line between below 2.5 and 5.5K (which is more important).

The +60 Metro pistons are rated as best production Aseries pistons and are good value.

Use Aldon 100AYV with Aldon Ingitor.

A
Anthony

Do you wanto do it yourself?
Go to Koen of classic car clinic Nijmegen and he will give you advice, can suply (quality)parts, and even do bits of work or maybe even the whole engine(if price is right) for you.

Whats your suspension set-up now?


Btw, you might wanto invest some of the 2K on a proper seat for Mirte?! ;)


Arie de Best

Thanx sofar keep the info coming.

Arie seats are already bought. Got a pair on Marktplaats from a MK II or MK III without headrest. Should look nice and sit even better.

What are the opinions on rockers? 1.3 or 1.5 roller or normal?
Bas Timmermans

For road use i'd say:

- 266 with 1.5 roller
- 276 with std rocker

... the engine I tried with 276 / 1.5 / single SU was a little more peaky than I expected/wanted for road, and very sensitive to cam timing (has to use a vernier to time properly). My 276 was fine timed +4 with offset key.

A
Anthony

My current 1275 + 266 + 1.5 rollers is extremely well behaved. Leads me to believe I could easily live with something peakier in a 1380.

This DVD gives a good detailed account of a 1380 build (albeit for a mini)
http://www.minispeed.co.uk/classic/index.cgi?task=showproduct&id=dvd-5

i totalled what that engine would have cost and including fancy lightweight ancillaries it comes to about £3500

I'm planning to do mine quite a bit cheaper :o
Dean Smith ('73 RWA)

I built a 1420cc and used a 286, std rockers, LCB, ported head by myself from Vizard details IIRC 1300GT sized valves. It was rolling roaded at 85bhp at the wheels. I always found it easy to drive with no tractibility problems.
David Billington

I have used 286 cams for many years without any problems whatsoever, mine have always driven without problems at low revs, tick over needs to be at least 1050 RPM but apart from that they are fantastic cams.

I have to state that IMO the cam choice is the most significant thing on any engine, but it needs the CR set to match it. This is simple to understand why? With a long duration cam trapping abilities are poor by comparrison to more standard shorter cams, especially at lower RPMs. Thus the "effective CR" of an engine with a hot cam needs more mechanical CR to compensate. Common sense really isn't it?

A good number of years ago a few friends of mine in the MGCC decided to start a race championship that was really cheap to compete in. Many of us aren't as rich as David, Max, Andrew and now Mark, so a cheap race championship was a great idea. They decided to have an MG Metro championship with few modifications to the engine (A Series) allowed. In the first few years the championship was struggling a little and I was asked to join it and race which I thought would be cheap fun, It was!!

Anyway now to the point. I built an engine to the standard specs which were basically, standard head and a 286 cam and 1330cc max. In the first couple of races I got slaughtered!! My car was being walked past on every straight by the championship "old hands". I soon understood why, a loop hole was that if you wanted to skim the head for perhaps a head gasket problem then that was permitted. Unbelievable I thought but if it is good for one then why not everyone. I skimmed my head to 11.5 / 1 and a 286 cam. On the rolling road that engine made 96BHP at the flywheel (measured correctly, not guessed) and seemed to go like turds of a shovel :-)))needless to say I was then able to compete.
Moral get the cam and CR correct and all else will be a bonus.

It did work against me however in the end as at the end of the season a certain Mike Garton (Spridget 50) sealed my engine and inspected it in the next few days (He was the tech scruitineer). Mike said this head is not standard! I had to agree with him and contested that I had had a few gasket failures, the same as everyone else in the championship. Mike was having none of it and did me 3 race wins 30 points. Fortunately I was far enough ahead not to worry. :-))
Competition was very moderate!
Bob (Robert) Midget Turbo

Bas, I aimed for 100bhp for my build and I have found it perfect, PERFECT.

I did:
Standard head, standard rockers, but ported.
276 Cam
1330cc (+60 overbore)
HIF44 & titan-like manifold, vizarded all the way :-)
Lightened (well, the special peter may steel one)
Competition 7.5" clutch
leccy ignition
performance distributor
Maniflow straight through big bore system

It is an absolutely lovely car in traffic, and on the wheels I get 100bhp. I also get a peak torque of 110 lbft

The torque is what sets it alight for me, it's just amazing to drive because it pulls and pulls and pulls.

HTH :-)
Rich Amos (1330cc Blaze Red '72)

WAIT. it's 100bhp at the fly, not the wheels. Oooops. That's some pub lies right there!
Rich Amos (1330cc Blaze Red '72)

A couple of points I think worth mentioning if you are only using it for road use:

Stick to the next size overbore from where your block is now. The extra few cc's aren't going to make much difference and these blocks are getting rare now.

Don't bother with balancing. It's expensive and won't give you any more power.

You should easily be able to do a full rebuild up to 100bhp and still leave some cash over to do your suspension mods.

John

John Payne

As John says above, only go to the next overbore unless you are competing, these blocks are not easy to find now and ultimately, they all will be oversize or scrap, remember they are NOT made anymore...!

Bob's comments on Cam choice and C/R are most valid and should serve to be the most important part of your engine build.

I cannot agree with John's suggestion about NOT balancing an engine, it maybe won't give you more power, but it will aid reliability and longevity.

My choice of Camshaft for road use would still be the SW5-07 from 848cc to 1480cc it works VERY well. Use 10.3 to 10.5:1 C/R.

I'm not a lover of the 1.5:1 roller rockers, in my experiance they are not reliable, try genuine Cooper S or Minispares 1.3:1s.

Your cylinder head can make or break an A series engine, so a correctly modified one, (one that suits the cam, bore, application etc) is well worth investing in. Peter Burgess will machine you a good one, as will Keith Calver or Nick Swift (if you can persuade him).

Finally Bob, what on earth makes you think I'm rich......! lol

Mark.
Mark T. Boldry

As soon as Mark gets some money he spends it! Toy rich, cash poor!
Tarquin

Excellent thread.....

I am in the middle of sourcing parts for an engine build and have been offered an ital a+ motor out of a post office van.

My thoughts were 1330cc but it was choosing the other elements like...

Mega Jolt
Aluminium Back Plate
etc etc

Shaun
Shaun

yeah know,

Maybe we can trade you some of our blocks for some of your type 9 5 speeds, we got lots of block here...no less then 3 on ebay at any given time...closer to 6 if you want all the parts....anywhere from $100 to $800

prop
Prop

"$100 to $800"

Thats € 15,- nowadays isnt it? ;)
Arie de Best

Shaun, ally backplate? Source yourself a Datsun Tranny and the Rivergate kit already has one:-)

I helped Rolf with his type 9 but against the Datsun its at least 30 or even moge Kgs heavier. Especially if its a 1500 conversion. That trans and especially the bellhouse weights a ton.
Bas Timmermans

But is'nt finding a datsun transmission just like trying to buy rocking horse manure?
Shaun

Mark nice one :-)

Feeling well off is a strange thing.

Years ago I used to think people with MGAs were better off than me, I would never be able to afford one and so that was my bench mark.

Anyway I was eventually given a laod of scrap that by beg borrowing and stealling I was able to build myself an MGA. So I had reached that height, now racing at european classic circuits is a bridge to far for my pocket so that is now my benchmark. Don't see though how I could ever achieve that.

:-))
Bob (Robert) Midget Turbo

we did the sums over and over again, a FISC season of 10 races over 4 weekends away was as cheap or cheaper than doing a full Midget series of 12 races over here. And the weather and food is generally better and the wine is cheaper, and weekends away are mini-holidays so brownie points too :-)
David Smith

try Keith Calver's RE13 cam shaft in something like a 1330 it should do way beter than the sw5 with only a mild increase in rough idling
But i do have a hardly used sw5 on "the shelf" if your intrested with valve springs to suit (even a hot head for your 1098)

and dependant on the cam but with the sw5 you need 1.5:1 and i think the re13 needs one as well

I also have a great adres for cylinderhead mods he realy can do a great 12G940

o Könemann

Onno,

Pleas mail me again with some info on that head modification adress. Good adresses are worth big money.

If the Sw5 is good and you have one spare I am interested!

Bas
Bas Timmermans

Ok, sofar, 100Bhp is reachable.

I learned:

1 stick to first overbore
2 Maniflow exhaust probably with RC40 silencer
3 1.3 rockers although some say 1.5
4 The biggest gain is in the head so a reputable specialist should do the porting
5 Cam and compresion rate are linked. 10 to 10.5 :1 is good for most cams.
6 Cams mentioned are 266 and 276 Kent, Swifttune SW5-07 and RE13. A bit rough is ok but it must bedrivable in city and if possible pull from max 2000 onwards. I dont want an engine that doesnt pull under 3000 RPM. What does the job? Onno if the SW5-07 is good and fairly new I am interested.

Any other advise on dizzy, electronic ignition, certain types of piston, vernier adjustable chain etc?

Bas
Bas Timmermans

This thread was discussed between 17/09/2008 and 22/09/2008

MG Midget and Sprite Technical index

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