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MG Midget and Sprite Technical - 1380 questions

At the moment my engine has to be over bored.

it now is at 060 so we need to go to 73.5 mm witch make's it a 1380 if i am correct.

my usual machine shop wil not do it be cause the can not guaranty it
An other shop wil do it and has no problems with it.

but if i understand vizard correctly it is wise to space the cylinder pairs 10 thou(how mutch mm??) out.
but how?
1&3 to the distibutor and 2&4 to the cam side or the other way around?
or is it both ok?

And it is a thin flange block witch is a bit less stif in the botom would this be a big no go?
remember it is a hot road engine not a race block
most of the times it wil not be reved over 5000rpm but on trackdays and rallys it will go past 6500

thanks for all advice
Onno (who does not want to buy an other block)Könemann
Onno Könemann

Now that has shocked me. I thought offset boring and I have had one or two blocks done, was always from the centre out. Therefore the very centre "land" between 2 and 3 remains the same and the oversize bore for cylinders 2 and 3 is machined from between them and 1 and 4. Then the oversize bore for 1 and 4 is machined from the outside of these 2 bores between them and the ends of the block. Have I been wrong all this time?
Robert (Bob) Midget Turbo

maby i misunder stood ??
Onno Könemann

I thought offset boring minimises the reduction in meat between #2 & #3; this is usually the most narrow part of the block and puts the gasket under most stress.

If you're going to +60, it makes sense to offset bore in case you want to go 1380 later.

You can't add metal back; and of course each successive bore has to be circular in x-section...

A
Anthony Cutler

I agree with Bob!!
There is minimal clearance between #s 2 and 3 at best, so to preserve that clearance offset boring moves the new centres of 1 & 2 towards the water pump, and the new centres of 3 & 4 towards the oil pump.
The thin flange block is actually better in one way because there is solid casting between and below the walls of #2 and #3, on a thick flange block there is a break-through which weakens it slightly. See pics on page 19 of Daniel's excellent book.
David Smith

Hey onno,

I maybe wrong, But I think you have to Off set the bores at 40 or less before going to the big bore,

ONNO, Im not an expert like I strive to be on the 1275, But give this some thought, your going to have alot of heating problems (to much), your going to lose alot of meat in the clyinders, and this engine is going to wear fast....probable need rebuilt every 50,ooo-75,000 miles, if this was a track engine that would be one thing, plus your talking about a complete new head that is completely punked out to take advantage of this engine the machine work will be high dollars, and no doulbt the type 9 tranny will need re-gearing to handle the power, off the hook brakes, wheels. and suspension system

Have you considard the "ford X-cross flow engine" they look just like the BMC engine, but the guts are super strong and can run susstained revs of 9xxx rpm, and a mass amount of after market parts....I think in stock form the turn out 98hp....200hp is not out of the question


At this point you might consider having the block re-sleved back to 60 over, or get a freash new block, that way you can stay with alot of what you already got.

ONNO, I know exactly where your at and understand why your making some of the decisions your making, we are waling side be side in this adventure, the differance Is my engine build is on indefinate hold trying to save money for a house, so I envy you But I have had great friends both here and about that have helped me avoid some dumb decision making.

prop

Agian look at ALL your options

.
Prop***The End in 2012

Onno,

This citate comes from minispares:
" he 1380 bore is 73.5mm. This is .120" oversize and should be offset bored "
Now, here their talking about .120, should this be divided by 2 to state the oversize? because 3mm = .120"
Or is a .60 oversize stated for the radius and not the diameter?

oohhw, got all confused now.

Alex"will be measuring tomorrow morning"Matla
Alex G Matla

prop go wash your mouth 5 speed and ford engine's bad boy ;)

No no engine swaps for me
i did mis under stood the offsetting of the bores i thought you would get the wall thinkness diagonaly.
and did not think about fwd/back because the rod does not hinge this way.

and i am not going to 060 i am at 060 an need to overbore (to 73.5 so a 1380)

according to Vizard you need to start ofseting at 73.5 so no need earlyer.
I do not have Daniels book YET but it is to late to get it before i have to make decisions

if i get 75000 miles out of the engine i will be satisfied because at that time (about 6/7 years) my super A-series will be about ready (verry nice plans so far)

a nice stage 3 head might be on the way already so that won't be a problem

buying an other blok has several down sides.
- costs money
- most likely will need maching two
- not a nice ballaced as it is now (or more costs)

so might order those big pistons
Onno Könemann

Peter May mailed if it is now at 060 (the bore is 72.3) than 73.5 is the next over size

witch is the first non std size if you do not count the minispares 73mm pistons witch i do not like because they give a relativly low compression.
Onno Könemann

Onno,

Our 1380 is based on the 'thin' flange block and has caused no problems related to the boring for 40,000+ miles.

The previous owner (up to 10,000 miles) had a piston burn out, but this was more likely due to wrong mixture/ignition than the overbore.

To run it in, use a good quality basic 20W/50 oil, nothing like semi or full synthetic, or the rings will never bed in and the oil consumption will be horrible! Mine was doing 150/200 per litre, until I had the bores re-honed and new rings - now 1,000+ per litre. The PO proudly told me that he had always run it on full synthetic from the day the engine was built - mistake! Change to a synthetic based oil if you prefer it after 1,000 miles.

I would get the whole bottom end balanced and fit a centre main bearing cap strap. Ours sees 7,000rpm regularly and doesn't seem to object at all.

It's a great spec to start form.

Richard
Richard Wale

Hey onno,

I just looked up vizard and gave a fast and dirty read

If its at 60 over now, then you can off-set over bore to 120, """BUT""" there are seveal issues, Agian I just read it fast and dirty, so dont quote me....you may need to stroke the crank, because the rods will hit the piston skirts and walls, you will need special dampers on the crankshaft hub and the flywheel, you will have big issues with CR so need deep dished pistons, the head needs to be completely re-done for this type of engine a longman head would be ideal because of there angled valves (Cha-ching), all so the machine work needs to be done by a 1275 experianced shop with the special jig for re-boring the clyinders because there is a common problem with tool wander and breaking into oil gallaries

But there is great news, mini mania has short block 1380s ready to go, for $2695, probably the way to go for this kind of set up takes all the unkown out of the picture....(at least in theory thats the case...LOL)

http://www.minimania.com/web/Item/1380%2FSHORTBLOCK/InvDetail.cfm

If you go for this, I want detailed pics, pricing and info, because this will be radical,,,not to mention un-godly expensive...my guess $8500 to $9000 (the head alone is going to run $3000)


Prop

.
Prop***The End in 2012

Hey Onno....

you wrote >>>>>>and i am not going to 060 i am at 060 an need to overbore (to 73.5 so a 1380) <<<<<<<

What i mean is you can get over sized clyinders $50 I think??? and have them machined and inserted back into the engine....you can go back to standard stock size if you like, I think they make them up to .60 over, so that way you can just re-use all your existing parts and have the engine at .60 over agian


look at number 25, this is a cude example Im betting peter may will have something better like I was discribing...but still this isnt a bad idea esp. at only $30 a clyinder...or was that $40.

http://mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36481

Prop
Prop***The End in 2012

The link to mini mania dost work...and I just realised the short block is for a mini cooper,

BUT

They do have a High performance 1380 for the MG midget, good for a 112 HP complete just drop in and drive, comes with everything for $6000 Not a bad price at all, for a complete high performance 1380 engine, you can add on a roller rocker and boost to 120 hp...mmm About $500-$700 extra, Id ask to get it at cost and save a couple hundred dollars

Also

They have the compelte 1380 kit, the head, pistons, cam hif6 carb, lifters, ect. everything except the block to do a high performance 1380 for only $4000, still not bad but by the time you spend $700 - $1000 dollars at the machine shop to bore out a 1380, your not that far off from an already High performance built engine ready to drop in hook up, add gas oil water, and drive

Just type in 1380 in the search box on the left side of the screen and press search and it will list about 15 items including everyting I mentioned. the UK sister site to this business is mini spares

Anyway....ought to be cool

Prop
Prop***The End in 2012

My two cents.
Over boring to 73.5 is going to cost a lot more than sleeving the cylinders.
If your pistons are in good condition you may be able to re-ring them. If not you can choose any bore size depending on the cost of the pistons. some sizes are cheaper than others.
Sleeving cylinders is a common job for engine rebuilders so most any shop can do this for you. You won't have to worry about everything working together. Save your money for the next engine.
J Bubela

Fact: You do NOT need to offset bore when going to 1380.

The reason people offset bore at 1380- is so they have a chance of reboring.

Read yer Vizard!
Deborah Evans

GEZ...why Re-bore to 74mm or 74.5mm, thats just nasty, time for a diffrant engine set-up....But Im thinking deborah is probably right just re-read some of vizard, and he seems to elude to this in a indirct way.


Deborah,

I hate to ask this, but I have an overwhelming curiosity....Is the name Deborah, a guys name in the UK?, I sorta found out that "Sandy" is a common guys name over in the UK also, but not real common here in the USA. No offence intended, and I mean nothing by it.... If your a guy, hey thats cool, I know 2 guys named ruby, So ....Its Just if your a woman, WOW, your really cool, not many women are as knowledgeable about the 1275 as you.


Prop
Prop***The End in 2012

Onno,
get it offset bored, Avonbar did mine, better start saving up though as Omega pistons are a bit expensive.

Prop,
i'm just wondering what type of special male friends you have with girls names?
Brad (Sprite IV 1380)

LOL....Well now that I think about it, there are several...LOL.

I know the 2 rubys I said all ready, 2 Dana's, a lynn, a morris, a michelle (okay so he is french...aka mike), several kellys, a lanny (but I think thats an old nick) and my sisters name is Jerrie


Apperantly, Im way to friendly when it comes to strangers....lol


prop
Prop***The End in 2012

Blue oyster bar?
Brad (Sprite IV 1380)

As in "Boy Goerge"

prop

Prop***The End in 2012

prop don't make it into a bigger deal than it is ;)
i am now looking at 1500euro's (overboring pistons and other work) max cost so your prices are way out of my range.

got a quote from Peter May 261 pounds without shipping and tax
sounds resonable think i will order them than
Onno Könemann

Onno, look up 'hypatec' pistons. They are certainly available here, and incredibly cheap. They will come flush to the top of a standard block. I run mine with hastings rings. http://www.minisport.com.au/ Mine cost me $210 for pistons, pins and rings (£95 at todays money).
Shawn

I must admit I always thought it was...

Offset bore desirable...but only absolutely necessary for the final 74mm bore. You couldn't offset from 73.5 to 74mm so you had to do it earlier if you wanted to.

At the moment a new block bored to 73.5mm is probably cheaper than a new set of 74mm pistons so its not the biggest concern ?
Dean Smith ('73 RWA)

dean you are totaly right according to vizzard.
How ever all the extra wall thickness between 2&3 is welcome

does anny one know if i have to shim or machine the piston /rod connection?
or is there enough play in it?
Onno Könemann

pistons ordered by the way
Onno Könemann

Prop,

I was female last time I looked!

My knowledge about the A Series motor comes from having built a racing Midget for a friend during the winter of 06/07 who then campaigned it over the last two race seasons. The pr.engines EMail address is for "Priestess Race Engines" - I build engines for people (and set up race cars), primarily specialising in the 'classics' for racing, ie A Series, Triumph 4-pot and 6-pot and so on. My real specialty is the Coventry Climax FW series such as those fitted to the Hillman Imp and its derivatives (a development of the FWM powerboat engine, but all deriving from the FWP firepump motor). I am currently building a Ginetta G15 for myself. If you are interested a record can be found at:

http://www.ginettaheritage.co.uk/phpbb/viewtopic.php?f=3&t=326

The 1380 in our race car was offset bored. However, after a long discussion with Simon Morton at Morspeed, this was done purely on the basis that, should the block ever need further reboring, this could not be done on a parallel bore. While offset boring on a 1380 does give increased wall thickness between numbers 2 and 3 cylinders (which is a good thing since it's usually here that the head gasket fails), it does put stress on the crank - indeed in Climax motors this is often the root cause of the failures that can occur. To make the A Series 'bomb proof' we use steel maincaps on all bearings, 4-bolt centre main and a Paul Ivey crank.



Earlier comments about CR on a 1380 are correct. We run Omega pistons with a 6cc dish giving (with the head work) a CR of 11.75 : 1. Not a problem on a race motor running 99 RON fuel (with a healthy splash of Millers CVL) and a 310 duration cam, but this wouldn't work on a road motor.

Here's a 'photo of the Midget - I'm the one wearing the cap


Deborah Evans

I always wanted to marry Sabine Schmidt, now I'm not so sure anymore!!!

Just imagine, no more bitching over that engine on the kitchen table or that casing in the oven...
Eddy Veuger

Eddy - these "strange" women are out there - my better half seriously believes the kitchen would be better as a garage....and would put HER frog in it.
d brenchley

Eddy

It's OK to marry Sabine ... just don't let her drive your Midget.

A
Anthony Cutler

to put one thing straight i never said 73,5 must be offset bored i said it was wise ;)

and about those woman mine keeps trying to steel the midget in stead of her (wel mine two actualy) classic mini!

might have to find her a nicer classic to keep the midget safe!
Onno Könemann

DEBorah,

OMG !!!! ARE YOU FREAKIN KIDDING ME!!! Im Totally in love, without a doulbt, you are the girl for me! Man, Wow! you really thur me for a loop, I came across one of your responses last week, and have been dumbfounded everscense, and didnt know what to think....Well NOW I do, your the cooliest girl I know, I cant belive the puppy dog crush Im going to have on you, gez. Amazing, truly Amazing.

Is this your carrer or a hobby, how did you learn your craft, what in life inspired you to go this path, how long have you been doing this, Are you self employeed or work for a shop, whats your favorite classic sports car....good grief, the questions I have are endless....LOL

well Im back to work...thanks for putting a skip in my heel for the afternoon

Prop...What a great day this is!!!...Prop
Prop***The End in 2012

Hey Onno,

Now that I have caught my breath lol., I think those are some great prices your getting the work done for, I do have to admit, mini mania is a bit proud of there prices, you said your getting a stage 3 head....which one is it and what are you going to have done to it, Id seriously have a look at the longman head, because of its angled valves, my understanding it breathes really well, to be honest Id give mark T, a shout, and see if he can find a westgate (8 port) or aldon 7 port head for you, not only would that give some nice horses, but the cool factor would be off the chart. what size valves are you going to use, Im guessing the HS2 su carbs are going to be way to small to make the most use of the engines potential, are you going to upgrade to the hif 6 or 44, or will you go to the HS4s, or some radical webber monster

this is going to be a really cool engine.

prop
Prop***The End in 2012

Prop my engine spec was pretty cool to begin with and will just be a continuation of that spec

original
-1275 bored to +60
-balanced and lightend crank/rods (std En16 but strong enough)
-oselli ported bigvalve head (now cracked dead)
-731 cam (vizard hates it i like it)
-weber 45 carb on long inlet
-tubilar exhaust manifold an repakable stainles damper (magik midget)


Now the engine will just be tweaked with
- boring to 73.5 (1380!!)
-center mainstrap fitting
-New head with big valves an fast ports (no big names but big flow numbers)

with the old spec the PO had it on a RR and it produced a healthy 84BHP
So i will be happy with something along those lines.

But in the next 5 years i will be building the ultimate (imo) A-series engine.
The way the works should have built some.

Onno Könemann

Deborah

Not trying to cast guilt but is that legal??
((((with a healthy splash of Millers CVL)))))
Don't have a blue book to hand at the mo :-))

Yep Onno, I was trying to be polite with my initial reply but you are now fully aware of offset boring.

My last normally aspirated engine was an offset bored 1400cc with a 286 and 11/1 CR. It was a brilliant engine and I only took it out of my car to fit the turbo. The turbo is a better engine because it makes great power at only 5.5 whereas the full potential of the 1400/ 286 did not come to maximum untill 7 thousand plus. When I get my turbo up to those revs it will be a very powerful beast. :-))

Hope you get yourself a great engine.
Robert (Bob) Midget Turbo

Rob,

CVL is perfectly legal, both from an FIA standpoint and an MSA one.

In fact there is a statement from both bodies to that intent.

AFAIK this is because CVL is seen as a valve lubricant/protector for older engines.

The fact it boosts octane by 3 points is a bonus. :)
Deborah Evans

Robert

i was aware of it all the time because i wrote the first post with vizard on my lap
i just did not make it realy clear ;P

btw i always use ron 98 fuel so high compression figures are what i am aiming at
Onno Könemann

Prop,

Thank you for your comments. I'm a wee bit overwhelmed!

Rather than hijack this thread further, Email me and I will try to answer your Q's.
Deborah Evans

Ohh Sabine...
Prop and to think that you are right in the middle of your engine rebuild. Now what are you going to do.
If you doink around much longer, its going to be the middle of summer before you get it back on the road.
So which head and what parts.
Man just get it together with what you have and build a second engine in your spare time. The fun is in the driving even if it is only slightly hot.

Allan
Allan Jacks

prop deborah
if we can facilitate the first bbs mariage here it is fine by me ;P
Onno Könemann

Hey Deborah,

Well what can I say, it all comes down to Context VS. Content.

As to the context, I certianly apologise for the tone and writtening style I used that led to the embarrasment you no doulbt experianced. That was both rude, and borish of me...

BUT

As to the content, well thats another story, I cant apologies for that, So no "Im sorrys" will be forth comming. I really Do think girls that are intellegent and mechanically savey like you, Are just So cool. and completely grab my full attention.

I wasnt able to deciepher your email address.

Prop
Prop***The End in 2012

Prop,

I didn't think you were being either rude or boorish.

I just don't normally elicit nice reactions like yours - most forums I am on I get told I know nothing because of my gender.
Deborah Evans

Deborah
I'm sure Prop will agree you are more than welcome here. The more input the better as far as I'm concerned specially from someone like you that's in there doing it.
On another subject, Would you know roughly what the average club racing Midget would weigh. I should start a new thread really I suppose but I've asked now so- When I weighed mine it went 520 kg ready to race with an empty tank and I would love to know how that compares to others. Cheers Willy
WilliamRevit

Willy,

Over here the MGCC regulations for the cars state a minimum weight of:

Class A (full Modsportscars - trick suspension, engines moved back, no roof): 510Kg

Class B (Race Modified cars - based around stock suspension): 580Kg

Class C (Roadgoing cars): 625Kg (A Series) / 705Kg (Triumph Engined)

A list if the Tech Regs can be found at:

http://www.mgmidgetchallenge.co.uk/Forms/
Deborah Evans

Prop,
Allow me to point out that your last heart throb, Kate, rebuilt her Midget's engine on her kitchen table.

OTOH, Sabine... MMMMmmmmm!
David "don't tell Trish (she already knows)" Lieb
David Lieb

Onno,

The 731 is short on lift with standard rocker ratio, where as the 544 will give you 388 lift (vs 320 on the 731.. if memory serves). The 544 also have 20 deg more duration

I have a 544 in my 1380, which I run with standard inexpensive rockers. The only trick being I have run a bead of MIG weld along the top surface to join the two sides of the pressed metal together, where they can separate due to compressive loads. Cam is timed to the 544 spec.

The engine also ballanced and the result realy is some thing specail.

My cam was 2nd hand with the engine, but if I was buying a new cam I would go for some thing with 400 thou lift and maybe 285 exhaust and 270 intake.

James
J E G Eastwood 1

Hey David,

Im not opposed to living a BI-Continital life style....LOL.

6 months in navada with kate, and 6 months in the Uk with Deborah...LOL

Yepp life would really be a kick, if that happened...LOL

Prop
Prop***The End in 2012

not buying a new cam and i am using 1.5 roler rockers (forgot to mention that)

When i have saved up enough money the aditions wil be a beltdrive, RE13 sw10 or VP cam (have not decided yet leaning towards the RE13)
And possibly a 7-port head with mapable ecu injection and ignition (so we can try the new E85 fuel's)

i only have to decide on what compression to run.
i only use ron 98 or higher and according to vizards chart (cam and octane)i could run almost 1.12 compression?!??!
seems a bit high to me
i was thinking of at least 1.10 maby a little bit higher?

can anybody enlighten me?
Onno Könemann

Might have spoken too soon! Nothing to do with the overbore to 1380, but at Silverstone last Monday, going down the Hanger Straight, had a sudden loss of power at almost 7,000rpm in 3rd. No noise, so crawled back to the pits, and got recovered home.

Took the engine apart today and the No.4 exhaust valve head has buried itself in the piston crown!

Bore looks ok, but not sure about the head - it will need a new guide and unleaded seat at best.


Richard Wale

Dosnt look to bad richard, a little JB weld will fix that right up

Prop
Prop***The End in 2012

not enough cooling?
nr4 runs a bit hotter some times
Onno Könemann

Terrible Richard. I wonder if the valve head has fractured and fell off the valve stem causing that damage, no sure it could happen by valve bounce?
Robert (Bob) Midget Turbo

Hey robert

Take another look, That is the valve head welded into the piston. Its sitting on its side.

Prop
Prop***The End in 2012

Yes so what does that mean? That is what I saw the first time why do I need to take another look?
Robert (Bob) Midget Turbo

This thread was discussed between 17/03/2009 and 29/03/2009

MG Midget and Sprite Technical index

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