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MG Midget and Sprite Technical - Curiosity beat me - dismantling my 1500 engine

Evening all,

Just noticed there is an A-series rebuild thread at the top of the listings so here I am starting one about a 1500 engine for balance. Cue jokes about boat anchors etc...

Anyway, curiosity got the better of me this evening and rather than mess around repairing more rusty bodywork I decided to whip out my spanners and see what I could see in my engine. Note, whilst I have done a fair bit of mechanic-ing I have never dismantled the bottom end of an engine before, hence lots of questions! Thanks for listening!

I have tried to get the head off numerous times and it is still stuck fast, so instead I took the sump off! First thing I noticed (see pic) was the bottom of no 1 con rod looks either machined or worn. Is this evidence of the rods being balanced or something worse?


Malcolm Le Chevalier

There is a matching indent in the sump... Has it been hitting the sump? I also notice that the bolts have nothing stamped on them (see pic one) whilst all other three sets of big end bolts have GSF amongst other things stamped on them.

Thoughts?


Malcolm Le Chevalier

Took off centre crank bearing. How does this look? (I will replace anyway whilst I can).

Malcolm Le Chevalier

Corresponding picture of crank. I noticed that the thread for the centre bearing cap was ‘missing’ the first two or so threads. You can sort of see in the picture where it is a different colour. Am I correct in my thinking that this is not original and done to ensure the stresses from the centre bearing are distributed deeper into the block?

Malcolm Le Chevalier

Finally, markings on the bearing. 0.010 U/S means the journal is ground 0.010 smaller than spec. in diameter right?

Thanks again everyone for listening and posting with what I imagine will be sage advice!

Cheers,
Malcolm


Malcolm Le Chevalier

Malcolm,
Centre main looks pretty good. Depending what the others are like you may well just getaway with new shells, same size. You might just wipe around the journal with some flour paper to re-polish it.
Recessed threads in the bolt hole are normal, I think. Doesn't the cap have corresponding collars that fit in there?
~1 big end shouldn't hit the sump like that. If you grasp the con rod, is there any up and down movement at all? -- = damaged shells or crank?
Guy

Or it may be more likely that the sump is deformed upwards if someone has used it as a jacking point. Certainly easier to fix if it is!!
Guy

get another sump if poss and see if that gives you the clearance that it should. . . .breakers yard or friendly thread poster. . .cant help, got an a type !
p bentley

#1 rod replaced after catastrophic failure, probably the crank as well. Rod has had additional grinding on the shank, somebody's "race prep". The marks on the rod are not the same event as those in the sump.
Yes on the threads, bearing markings.
Crank looks good.
Looks like you might have a recently rebuilt engine, albeit with mismatched rod.

FRM
FR Millmore

additional note, I think there were similar albeit smaller machining? markings on (I think it was) no. 3 big end.

and yes, all the rods also appeared to have ground or lightly polished shanks but I dont have a picture of these things.

No history on the engine, hence the stripping just in case. All I know is that it aint original as it has the ESS prefix on the engine number meaning 'warranty spare' or something similar.

Cheers FRM,

Malcolm
Malcolm Le Chevalier

not prefix, the oppostie (post fix?) ESS after the engine number I mean. Shouldn't try shaving and posting at the same time!

Malcolm
Malcolm Le Chevalier

Hi Malcolm, I have just finished putting mine back together again this past weekend. I would agree with the coments above - the bearing and crank look pretty good.

The rod end polishing can't be from hittng the sump - apart from anything else it would make an absolute din. I can't see any marks in the sump pic that would match up.. I am with FRM I would imagine that someones handy work from prior rebuild.

Whilst its apart check the crank endfloat and put it back would be my advice. It looks as though there is not much wrong...

To get the head off try turning the crank over with a breaker bar the compression may do the trick and pop the head seal....?
John Barber

Might have been a few recons/blowups since the ESS number too.

FRM
FR Millmore

Probably! But wouldn't there often be a con rod shaped hole in the block after blowing up?

It certainly hasn't done many miles in the past two decades. I have MOT certificates back to the mid 90s, it only did about 250 miles a year up until failing it's MOT in 2005 due to rot.

Malcolm
Malcolm Le Chevalier

"But wouldn't there often be a con rod shaped hole in the block after blowing up?"
Indeed, and it was quite common when there were lots of these cars running about. Couldn't tell you how many times I saw a trail of oil on the road with a dead Spitfire at the end. But believe it or not, some few people shut it off when it starts to clatter.

FRM
FR Millmore

Malcolm,
you should know by now what curiosity did!
On the upside the engine looks like it has been worked on by someone who's read some of the right books.
Mains thread undercut by a couple of threads does get the stresses deeper in to the block and isn't standard. The rods need to be weighed to find out if the "machining" has been done to balance them. Crank bearing surfaces look okay but measure anyway and they are .010 undersize. Check your new bearings line up correctly with the oil way and "adjust carefully" if not. With a bit of luck the oil way to the centre main will have been increased in diameter to 5/16".
I could go on and on.... better to read all about the 1500 engine here;
http://www.totallytriumph.net/spitfire/engine_building.shtml
BTW getting the head off... try the usual two nut trick. If that fails rig up a starter motor, crank it and use the compression to lift it (assuming it still has some!). If that's a no go, take the crank and pistons out from the bottom and give it a whack with a big heavy "persuader" and some wood down the bores. after soaking the studs with a good pen oil of a long time...

You know where to reach me if you need a pointer or two.

Best of
MGmike
M McAndrew

Mike-
"Mains thread undercut by a couple of threads does get the stresses deeper in to the block and isn't standard."
I will stand corrected if you know this as fact, but it is very common on most engines, Maybe another late BL cost saver?
Are you certain pistons will come out the bottom? Most modern engines will not, but they might come far enough to have some rings ppop out of the bore - most difficult to get them back so the pistons can go back up!

FRM
FR Millmore

FRM
I know it as fact on the 74 block I pulled apart last winter. Can't comment on later blocks but I'd be very surprised if BL added an extra machining step in the process which would increase cost. But there again nothing BL did in the 70's should surprise ;O)
I'm not 100% sure the pistons will come out the bottom and Malcolm should check before doing so. There is a possibility the pistons will catch on the block webs which could prevent them coming out. Unlike most engines the main caps are "located" using machined surfaces in the block and I presume, line bored. Other (more modern A and B series lol) engines use tube dowels through which the bolt pass for location.
I'm not advocating putting the pistons back from the bottom! That would be almost impossible as there is little room to get the ring compressor in close to the bore. As Malcolm intends to take the head off (which is stuck on the studs) the pistons should go back in from the top as normal.

MGmike

M McAndrew

I wish it was stuck on the studs! That is what is what is so annoying. I have removed all the head studs, and even battering it with a big (soft faced) hammer the head will not budge!

Didnt get out to the garage last night, but looking at my pictures again it looks like the crank has had some machining done to it as well? (on the flappy bits whatever they are called? pic. 4, bottom left corner)

edit: what is the two nut trick? I did try turning it over by hand ages ago to pop it but nothing happened!

Cheers,
Malcolm
Malcolm Le Chevalier

Malcolm - if you're SERIOUS about this engine rebuild, and the car running way way better than the midget lot will ever know - then, there's alot of work that you can do the crank - including having it cross-drilled and then you need to get it balanced. Of course, there's alot of people on here who have 1500s but don't really want them to run properly, but, if you do - then, there's LOADS you can do to it. The link that Mike put up is only the begining and only a guide to what can be done, and how it affects it.

There's as much information out there about modifying the 1500 engine as there is about the A-series - you just have to get off the Midget boards, and look to the Triumph guys - Kas Kastner also has written several books. You also have to improve the oil flow to many other areas - there are a couple of "kits" that will do that, but you also need to do it to the 1st bearing.


It's up to you really - do it cheaply and fix it up how BL managed to ruin it - or do it properly and have mega-fun!
rachmacb

read that article numerous times, and debs article:

http://www.british-cars.org/mg-midget-sprite-technical-bbs/the-bad-historyof-the-1500-crankshaft-2010011622103913152.htm

Thanks for the inspirational pep talk Rach! :-)

I was stripping it because of a. boredom, b. curiosity/learning, c. I had no idea what condition it was in as never had it running.

I just want something that will run well and not blow up at the drop of a hat! If I can get the car back together and working well it will be an achievement and having never driven (or ridden) in a Midget before just having something that works will be amazing!

All this work that has (possibly) been done already is just a bonus. The engine appears to be the only decent bit of the car, everything else is/was shot!

Cheers,
Malcolm
Malcolm Le Chevalier

LOL you're welcome - and you do have my e-mail address from the speedo link if you want any other links stuff - people to talk to - etc etc.

Sadly, with the horses, I never get up to see my parents, so can't offer to let you drive mine - but, if you're ever down this way, then you'd be more than welcome.

I was very lucky - when I got my car, for sure, the bodywork was (IS) dire - but, she was working for a few years - so I was able to know what I was going for - then I got a few pleasant surprises when I took some of the engine to pieces! I was then able to use her in a few competitions, and she went out of her way to prove herself - so I at least I know what I'm missing whilst the body was broken ;)
rachmacb

In my garage, posting on my phone...

So many more pictures and questions when I get home! Hope you are all ready! :-D

Malcolm
Malcolm Le Chevalier

Malcolm,
two nut trick is to put two nuts on each stud, tighten them together and use the lower one to screw the stud out. But if you've got them all out it won't work ;o)
If they're all out and its only the gasket holding it, its back to plan A the BIG persuader! A soft mallet is all well and good but you'll need to give it some to shift it.

Rach, if I was a sensitive man I could get very upset at you inferring I know nowt about these engine thingies ;o) LOL

BTW Malcolm, If you can't get down to see Rach, let me know if you are ever in Edinburgh and I'll commandeer the Midget from it's owner for a blast. You can then take the big brother (B) for a blast as a comparison... Wait long enough and you never know the V8 might be on the road... Now that will be a blast....

MGmike
M McAndrew

Head came off with a good pounding with my rubber basher. Nice stress reliever!

Quickly cleaned up some of the crud with a scouring pad. Looks a bit rusted...

Malcolm

Malcolm Le Chevalier

Bores look a bit rusty too, but hopefully will clean up ok?!

Malcolm Le Chevalier

back to the bottom end, loads of bits have been machined off the crank. Does this look typical for a balanced crank? I thought it looked a bit drastic!

3 of the rods have machining marks of differing size. Guessing they have been balanced to the lightest one (the one with no marks, obviously!).

Checked end float, not sure if I did it correctly... I can feel the crank move with a small 'clonk' fore and aft. Pushed back I squeezed about 40 thou feeler guage between crank and last bearing cap. Pulled the crank forward and measured again, 46 thou.

MGMike, do you realise I am a 24 year old yooth and only passed my test last July! ha ha! :-)

Cheers
Malcolm

Malcolm Le Chevalier

The bore tops look a little worse than you would like malcolm. I assume this has stood for while like mine had. The bores may need a glaze bust at least to prevent ring problems at the tp of the stroke ..

I am not sure about the crank machining - could be balance.

Like you my rebuild is more to just get a reliable engine not a power increase as such..


The other comment relates to cost - all the gaskets/seal and bits you end up re-newing when you pull it apart cn add up to some serious money. If you are on a budget and need to spend money on suspension/body and brakes - then you may want to think twice about a total strip .. However maybe its too late now...

John Barber

Malcolm,
24! you ain't getting your hands on the V8 then!! Might still let you have a shot in the B but only under strict supervision :o)
Now you've come this far you might as well make sure it's right as you rebuild. The crank looks a bit strange with bits hacked off it but perhaps others have seen something like it before.
The head looks like it may have been worked on also but I would need to see a better picture of one of the chambers after it's cleaned up, which it will do with either a grit blast or plenty of elbow grease. Clean the carbon off one of the piston crowns to see if there are any markings to indicate oversize pistons. Clean off the ring of carbon around the top of the bore with fine(ish) grit paper before pushing the pistons out. Check for a wear ridge in the bores.
The crank end float needs checking again! Did you see any thrust washers? End float (from memory) should be 3-5 thou and whist you might feel it you shouldn't be able to hear it!

Keep the updates coming.

MGmike
M McAndrew

Its a bit of an assumption I know, but I would take a gamble that with all that work on the bottom end whoever did it knew what they were doing. Other than light polishing of the journals I would put it back together as is, just with new shells and thrust washers. You could do a check with some plastigauge to be sure.

Looks like it had blown the head gasket - water in bores and hence rusting. Not ideal, but should clean up well enough with a bore hone.

I would guess that with the bottom end work it may well also have raised compression (although this should be just gentle on the 1500). And very likely a non standard cam as well. It seems unlikely that someone would do that bottom end work and not bother with these other items as well.

Get it back together and you could have a nice fast road engine at a very reasonable cost!

Guy
Guy

LOL Mike - THAT would be very over sensitive indeed - as you know I respect you enough to "babysit" Bluebell!!!!

Guy's points about the cam and top end are also very valid and you do seem to have got a good engine there Malcolm - so you need to do it properly - the crank just needs a bit of extra oil - and one good option for cams if it's not done is the Spitfire 1300. But, one thing I would advise is to get one that has a wide profile - not just all whizzy top end - the big advantage you have with the 1500 is the torque - don't lose it trying to over-rev it - unless you are going to do ALL the work necessary to allow that in the engine! There's little point in doing that in many ways!

LOL and tell Mike he's being a wimp for not letting you drive his V8 - I was allowed not only to drive one - but also to autotest one last year :P And you're probably less dangerous than me ;)
rachmacb

Thanks guys, I am going to do a full strip anyway just for curiosity sake! The block and head are pretty grubby inside and out so it will allow me to get them deep cleaned then I will just rebuild as is with new seals and gaskets etc.

At least it will have saved me a couple of 100s if not more for a full rebuild kit + machining work.

I really should get on and do some more welding...

Malcolm
Malcolm Le Chevalier

Malcolm - just check that the con-rods are ok - they can go a bit "egg shaped".

Enjoy the welding!
rachmacb

more updates! took no. 1 piston out this evening. Piture of rod and piston... is the speed hole factory or a bit of added lightness?

Malcolm Le Chevalier

con rod nicely polished...

Malcolm Le Chevalier

big end bearings are + 10 thou just like crank mains. Look OK I think? but will replace for the sake of £15.

Malcolm Le Chevalier

and the big find... some fat + 40 thou pistons :-D next job is to find out what camshaft my engine has.

Two things strike me as odd. 1. this engine was in a disastourously poor shell with knackered suspension and brakes! 2. it still only had the crap cast exhaust manifold. surely a tubular one would be a good upgrade?!

Cheers all, im a happy bunny. Finally found a good bit of my car! Just gonna strip, clean and rebuild with new bearings and bolts. Will spend the savings on said exhaust and oil cooler!

Cheers,
Malcolm

p.s. hope all my pistons are + 40, not just this one! ha ha, suspicious due to no 1 rod bolts being different to other three!

Malcolm Le Chevalier

Nice!

Is the engine number correct for the car?
Maybe the previous owner bought an engine as a replacement and didn't know what he had got hold of. Just put it into his tired old car and fitted it up to the existing manifold.
Guy

"p.s. hope all my pistons are + 40, not just this one! ha ha, suspicious due to no 1 rod bolts being different to other three!"

Don't laugh. Guy I knew c1966 had a pretty new Volvo 122S, which blew up with a clatter. Took it to the dealer who fixed it under warranty. After numerous trips back complaining of very poor idle, he brought it to us. We could not get it to smooth out and the carb settings were all goofy, Comp check showed very high in 3&4, normal in 1&2. Took it apart to find they had bored it in the car - two holes only - and fitted two +.060 pistons! Much gnashing of teeth and talk of lawyers later, we rebuilt it correctly and the dealer ate the bill.

FRM
FR Millmore

Hate to break the bubble - but, Ivor Searle do produce engines which are sold as recon ones that have +40 as standard - nice engines though ;) <grin>!!!!
rachmacb

reckon I will be able to get the crank nut off with a 46 mm slogging spanner?

was in a rush in the tool shop at lunchtime and just grabbed the first thing that was 46 mm and spanner shaped. Now wondering if it will go on the nut and if I will be able to whack it hard enough to get it loose...

Malcolm
Malcolm Le Chevalier

as ever, typed question then trawled the internet to try and find the answer myself! looked at a few pics, the nut sticks out enough that i should be able to get it on. Just need a big enough hammer! more stress relieving! :-)

Malcolm
Malcolm Le Chevalier

Malcolm:

You might want to consider a big lever rather than a big hammer, that nut is on pretty tight. When I did mine it took the socket and bar with pipe extension in the pic, along with a lot of my 180 lbs. to break it loose. Likewise returning it, you will want a lot of torque. Don't forget a stout block of wood between crank and block to keep it from rotating.

Richard

Richard Reeves

I had to use an impact socket and air power impact wrench to get mine undone..

John Barber

Just in the garage now. Wedged crank, couple of not even heavy handed blows with a heavy rubber mallet on my new slogging spanner and it was loose. Too easy, don't know what the fuss was about :-)

All pistons are plus 40. About to take timing cover off. If BL were so keen on rationalisation why are all the cover fasteners different?!

Malcolm
Malcolm Le Chevalier

Beware when doing up the bottom 2 (or is it 3) on a 1500 engine. They screw into the "bridge" piece over the front main, which is alloy. Easy to overtighten and strip. Not sure that they don't also use a coarse thread as well. They also need to be the right length. If replaced with over long ones they will punch through the blind end of the threaded hole and provide a good oil leakage route from the sump. So there is a reason for BL's non-standardisation in this case!
Guy

Any idea what this camshaft is? This is the only marking on it (see pic) "41AV". Other than an unreadable (what I guess is a) casting number.

Cheers all, hope you are enjoying the story!

Malcolm

Malcolm Le Chevalier

This thread was discussed between 30/04/2012 and 05/05/2012

MG Midget and Sprite Technical index

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