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MG Midget and Sprite Technical - New engine won't fire up

I can't get my new 1380 engine to fire up. I have (double) checked the timing (both mecahnical and electrical) and I am getting sparks at all plugs in the correct order. The problem appears to be that the starter (standard and about 100 sprint miles old) does not have the grunt to turn the engine over fast enough. Without the plugs in it turns much faster but when it faces serious compression (the block/head has been machined for a CR of 12:1 and there are stronger valve springs), it gives all the signs of a duff battery. I replaced the battery and even with another in parallel it makes no difference to the speed of engine turnover.

Before I shell out oodles of money on a hi torque starter motor is there anything I can try to home in on the problem?

As always, all help greatly appreciated

John
John Turner (Midget & MGB)

Until someone comes along with the technical stuff I'll put the obvious that might be missed - battery connections, leads, wires and other conections elsewhere including earths
Nigel Atkins

I had similar problems with my first start. I think it's the high friction of all new parts. Be careful not to cook the starter. And with that CR a high torque starter might be a good idea anyway.
Alex G Matla

Many years ago I had a new Ford engine that would not turn over quickly enough to fire and run, although I knew all the systems were working correctly.
It was new engine tightness that was just too much for the starter.
The ignominious solution was to be towed until it started, and the engine was fine, after running in for a while to lose the initial tightness.
I wouldn't want to be towed now though, looks like you have a wreck of a car which is the complete opposite of the truth!
Apart from that, as Nigel says, double check the obvious electrical connections.
A more powerful starter might be the way to go if everything else checks out.
JB Anderson

What everyone else said + check the number of teeth on the starter pinion and see if you can get one with less teeth, for lower gearing and more torque for starting.
Daniel Thirteen-Twelve

I suppose you did check that the engine would turn over freely before installing it?

You should be able to turn the crank and pistons (with head off by hand) and with a socket and bar on the pulley with the head on.
Chris H (1970 Midget 1275)

After replacing a blown head gasket on a camping holiday in Scotland once on a 1500 it just wouldn't start. It had a raised compression engine and this was enough to take the edge off the starter "spin". Eventually I got a tow start and 30 yards down the road it fired up. After that it was fine.

I suspect the problem is with the SU carbs. The engine has to spin fast enough to get a good venturi effect going over the jet. With an engine that has been run before there will always be some residual petrol vapour in the cylinders, but with a new build you are starting from dry.

I have also persuaded reluctant starters by feeding gas from a butane blow lamp direct into the spark plug holes before trying the starter.
Guy

I am (as always it seems with Guy)

A bit of go go juice direct into the throat generally helps on very first start of a high performance engine.

I like the gas idea although I drip a few drops of fuel directly into the throat of the carb/s

A lot of the problem comes from the engine being very clean just seems to be too cold on the internal surfaces.
Robert (Bob) Midget Turbo

I rebuilt a Datsun 240Z with twin SU's and had a similar problem. Just not cranking faster enough to draw the fuel through.

For a little while I had to spray fuel in the carbies (only a few starts I think) and it started straight away. I put it in a spray bottle so I could control how much went in and it was misted. Same problem tight engine, no accelerator pump like a conventional carby and not enough speed to draw the fuel in.

Obviously be careful if you try this. After a bit of running it may be ok but with 12:1 it could still be a struggle.
Greg H

Thanks for the help

I will check the earths. The engine turned freely without the head during assembly. I have also tried squirting fuel from a vapouriser bottle into the bellmouths of the DCOE (the plugs are showing fuel getting into the cylinders). The idea of a tow is good (I had to do this with a Ford xFlow engine in a Cortina GT many years ago) but my problem is that the car needs to be running to get it out of my garage and garden and onto the road!

The batteries have been on charge again last night so will give it another go before going the Hi Torque route

Thanks again

John
John Turner (Midget & MGB)

Success!

With the help of a glamourous assistant (aka 'the wife') squirting fuel into the trumpets whilst I turned the key and pumped the throttle, the engine fired!

Ran it for a few minutes (oil pressure came up very quickly - always a relief) and then tried again a bit later after I had bolted a few more bits back on. It fired and ran but turnover was slow. Hopefully once the engine loosens up a bit it will be easier starting and I won't need to get a stronger starter motor.

John 'feeling rather smug' Turner!!!!!
John Turner (Midget & MGB)

DCOE?

The Weber has a fuel pump John, so I am surprised simply pumping the throttle during initial cranking ought to have started it? is the throttle pump working correctly?

Anyway it's going now so well done.
Robert (Bob) Midget Turbo

Bob,

Yes the accelerator pump is working - I have always had to pump to get it going - the cold start device is useless as most DCOE users know.

Even though it started, the engine turned over very slowly so it seems that the extra fuel was needed.

Hopefully in the future it will start just on the pump once things have loosened up even with the high compression - we shall see!

John
John Turner (Midget & MGB)

""the cold start device is useless as most DCOE users know.""
Do we? not heard that one before?

The 45 on my MGA is spot on without the cold start I am not sure the car wou;d start ver well during coldish weather so it certainly works fine I am pleased to say..

Robert (Bob) Midget Turbo

Shouldn't the "glamorous assistant" NOT have been doing the Dangerous Potentially Explosive Fuel part? :p
Richard Reeves

This thread was discussed between 08/03/2011 and 09/03/2011

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