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MG Midget and Sprite Technical - Rebuilt Engine Won't Start

Hello,

i have recently had my 1275 engine rebuilt and is now in the car.

i have installed a 123 ignition system and believe this is set up correctly. i have had a couple of coughs but are random and infrequent.

i am feeling at a loss now, and would like some advice to systematically work through the issue.

any takers?

many thanks in advance

pete
P J Gingell

A few basics Pete...

Definitely have fuel at the carbs? Check by disconnecting hose, putting it into a coke bottle and turning the engine over.

Oil pressure good when cranking over?

Do you have a spark at each plug? Remove each one, ground it against the block, turn the engine over and check for a spark.

Check the plug leads are on the correct way round. Then have a cup of tea and check again.

Check ignition timing. Check it isn't 180 degrees out.

Its probably something simple. Don't get disheartened!

Cheers,
Mal
M Le Chevalier

As Malcolm said, check that the timing isn't 180 degrees out.

Set no. 1 cylinder to TDC on compression stroke (both valves closed). See if the rotor arm is pointing to no. 1 plug lead.
Dave O'Neill 2

Make sure you got oil in the dashpots of the carbs...
I know it sounds ridiculous, but I actually couldn't get mine to start because they were empty.
Choke on helps too. Looks like Malc nailed the basics...Oh good luck with it! Nothing more rewarding than watching it run! :-)
Steven Devine

thanks guys, appreciate the help,

fuel is there,
definitely at TDC on compression (check, double checked and checked again several more times!)
correct firing order,
have only checked spark on no1, will check thee rest next thanks,
rotor arm does point to no1,
oil is dash pots.

with old distributor i tried advancing/retarding dissy, it mangaed to fire being advanced by a lot, but wouldn't rev above 500rpm

what next?

cheers again
P J Gingell

A fully rebuilt engine can be a bit tight and if the starter is taking most of the power from the battery, there may not be enough left to make a good enough spark. Also, the compression will be low until the rings bed in.
Do all the checks, then try towing it in second gear (ignition on) to bump start it. That way, all the power is going to the ignition and not the starter.

Bernie.
b higginson

Double, and treble check the firing order. Anticlockwise, as you look at the dizzy, 1342

If you have fitted an air filter, make sure that you have it the right way up and haven't obstructed the air flow holes in the carb flange. This will prevent the dashpot piston from lifting, so keeping revs low.
Guy Weller

yeap I'm with Guy again double check the firing order

by coincidence I was with a mate doing a couple of jobs on my midget in his garage (so much better than working outside in the wind or rain) one of the jobs was to fit the 123

he's a very experienced mechanic but when we fired the car up to check everything out after a while he said why is (can't remember now) glowing - turned out the HT leads were in the wrong order, he'd connected them

if I'd have connected them I'd have took three times as long as I'd have to recheck them as I don't trust myself - but they would have been in the right order

if you look in the Archives you'll see a thread I put up called 'Firing order' to confirm and illustrate the correct firing order but Guy has put it very succinctly
Nigel Atkins

When I tried to fire up my newly-built engine a while ago, I used up two whole battery charges. My theory was that the huge amount of assembly lube I'd used was gumming up the works. I imagined a gloopy tide washing up and down the bores on top of the pistons. Even thought about taking the head off to clean up a bit.



But it was the firing order.
Nick and Cherry Scoop

Have you checked carb initial settings and float settings.
mark 1500 Lights on at the end of the tunnel

Normally I would say spark plug firing order, but then you said this....


"""with old distributor i tried advancing/retarding dissy, it mangaed to fire being advanced by a lot, but wouldn't rev above 500rpm """

Obviously it ran just not very well....

id say make sure the spark plug firing order is correct, im sure it is, as you wouldnt make that mistake twice in a row haveing had the 123 in and not running, then out and and having the old dissy in running then replacing the dissy with the 123 in agian and not running

Im going out ona limb and just guessing its got to be the camshaft timing is set incorrectly...granted theres other possiablities...its just my 2 cents

Id go back to the old dissy for now being its a know good part and get the engine.running correctly with it, then convert to the 123....right now as it sits, there are to many veriables in place that will have to be worked thur

This thread just got interesting

Prop
Prop and the Blackhole Midget

If not cam shaft timing... are you sure your valve lash is adjusted correctly

Rule of 9

Prop
Prop and the Blackhole Midget

Okay... one last thought

Ive heard that if (#2 & #3 ) are reversed then the engine will run but not very well also

Im not sure why that wont work on your 123 but would on the old dissy

But its a simple easy check to scratch off the list

Prop
Prop and the Blackhole Midget

Worth checking the top dead centre mark on the crank pulley actually is. Mine wasn't, didn't run at all, just weird backfiring and trying to start the engine backwards..
Rob Armstrong

so 4 reverse and 1 forward gear Rob? Must have been entertaining to drive...
Dominic Excell

I think I mentioned this before on another thread, but the distributor, after long storage, often needs a really good blast of WD40 to fill hairline cracks that can carry the charge away to earth. Here's my non-starting-newly-built engine story from my old website; it's about a Subaru but the story is the same... http://www.nagara.co.uk/enginestart.htm

It's worth a try!
N.C. Nakorn

It never started, made 2 huge bangs set fire to the inside of one of the air filters briefly, after much surprise and some choice words we put it together again better...
Rob Armstrong

If it's a new dizzy cap make sure, if it is side entry, it isn't 90 degrees out. There are some like that coming through the supply chain. I got one from MOSS recently and took it back. It points the leads the wrong way and changes the firing order. 1342 becomes 3421 (or it could have been 2134, can't remember now) and you get spitting back through carb and bangs out the exhaust.

Rob
Rob aka MG Moneypit

as I put it in the other thread I'll put it here too - for caps, condensers, rotor arms, (points), etc. got to the Distributor Doctor - http://www.distributordoctor.com/
Nigel Atkins

Well...did it ever run?
Steven Devine

Rob

Im trying to think back... is that th engine that was sold to someone here on the board and they just got it running a few weeks back


I cant remember what the issue was that got it running IIRC

Prop
Prop and the Blackhole Midget

Yes - I can fully empathize with checking any air holes in the mating faces of the carb(s) are not blocked by a gasket or air filter. I had very similar symptoms when fitting an after market air filer. Took me ages to find it. Pull the filter completely off and check.....otherwise check all carb hoses for leaks/fitment, check the mixture, and are all carb jets scrupulously clean? - crud gets in there easily especially after a rebuild.
Mark O

" --- with old distributor i tried advancing/retarding dissy, it mangaed to fire being advanced by a lot, but wouldn't rev above 500rpm --- "

Who built it? Are they sure they got the cam timing right? Dimples?
Lawrence Slater

Thanks lawerance... that was my orginal question also... camshaft timing? Now its just the 2 of us,

If your going to be spectacularly wrong, then bring a like mineded friend to enjoy the experiance

Prop
Prop and the Blackhole Midget

Rob. . you mention Dizzy cap being side entry, mines top entry. . is there a switch over on these ? not saying mines right, just curious
P Bentley

looks like July 1967
Nigel Atkins

P Bently. I thought they were all side entry? Top entry puts the leads very near the steering column and with a bit of rubbing could provide a handy path to earth for the spark.

The trouble I had starting my engine was it was fitted with an A+ crank pulley damper. The A+ has the timing mark between the alternator and waterpump with the indicators mounted to the timing chain cover visible from the top of the engine bay. The guy who rebuilt my engine timed it assuming it was a proper Midget pulley and put the distributor drive in the wrong place. Took a while to figure out but the BBS sorted me out.

Rob
Rob aka MG Moneypit

no, top entry and side entry depending on model year/month
Nigel Atkins

Well, thanks for all your responses.

i went out after reading suggestions, checked firing order; correct.

then took no1 plug off to check sparks again, nothing.

now it was sparking before and i did have it running (sort of, almost)

so i must have a wiring problem :(


been out just now with multi meter trying to see what the problem is.

now i think i have a short somewhere, please check my reasoning- i have set the meter to "buzz" and connected one end to the live (which connetcts to positve on dissy) wire and the other to earth and it sounds; this shouldn't be should it?

there is also no Volts showing when ignition is on.

i wonder if a dodgy bit of wiring somewhere would cause my problems?

any advice? i'm close to taking it to the garage, but want the satisfaction of fixing it myself. i've not done much with electrics in cars and am getting a little frustrated with the jumble of wires behind the dash!

P J Gingell

Put the 25d4 back on with points and condenser.

Rig a permanent live to the coil, and a lead from the coil to the points. You can't get simpler wiring than that.

Set the timing to static, and spin it over.

Report what happens

Lawrence Slater

What lawerance says

Positive side of battry to positive side of coil, and try and start it

If it starts the problem is in the ignition key area most likely

If it does start... it wont shut off with the key, ither kill it by smoothering the carbs or yanking the positive wire to the coil

Prop
Prop and the Blackhole Midget

If it was contacts and the body of the dizzy was reading live I would say you had the wire to the contacts on the wrong way. (you can turn it over through 180 degrees and it still physically fits but fouls the dizzy body and therefore shorts).

Just trying to be helpful.
Dave Squire

Knowing nothing about electrics, but when I switched to Accuspark electronics, the wiring was reversed.

Nick and Cherry Scoop

And the results were?
Steven Devine

Sad steven so sad.... electrical fire, melted his eye lashes off
Prop and the Blackhole Midget

Oh - sorry.

Brilliant - but I have been driving around with the old dizz, the right tools AND the instructions in the boot, just in case my electronic set-up has teething problems.

The lashes are stiil there, Prop. Sadly, the major hair loss is higher up.
Nick and Cherry Scoop

Haha... my hair line is on the rise as well

Prop
Prop and the Blackhole Midget

This thread was discussed between 07/06/2014 and 17/06/2014

MG Midget and Sprite Technical index

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