1098cc Engine Compression

[blue_cortina]

Hi Everyone
Sine my son bought his Moggie we have been recommissioning it to go back on the road. It's ended up in a state where it rally doesn't want to start. As far as I know Moggies are very easy to start, (?). I thought as a basic check I'd doa compression test - so admittedly its not with the engine hot, or the throttle wide open - so not how you are really meant to do it - but if it isn't starting that is difficult. I'm getting 135,135,130,140. I've tried to look at the engine number but the plate is missing and can't find anything in the old paperwork with the car. What's you opinion on the numbers?

[oliver90owner]

It won’t be the compression that is preventing it starting if those are psi values. Compression results are notoriously inaccurate in absolute terms, but those figures are all quite close, which is good. Guessing you have good valve clearances?

[SEROWMANMICHAEL]

Follow the old saying COMPRESSION/IGNITION/CARBURATION

[oliver90owner]

OK, further comment.

Is there a spark? If so, what colour?

Are the plugs wet? If not, likely no fuel.

Is the fuel pump ticking at ignition turn-on then only occasionally?

Is the fuel fresh? All of it?

[Monty-4]

Decent numbers I think. I got around 160psi on a tuned engine with slightly raised compression.

[simmitc]

Compressions sounds OK. Go back to basics in the ignition.
Points cap 15 thou.
Plug caqp 25 thou
Remove all plugs, thumb over No. 1 hole (front of engine) and turn on handle until you feel compression building.
Look at timing marks and continue turning engine until about 4 degrees BTDC,
Adjust distributor until points just opening.
Note to where the rotor arm is pointing, and ensure that the correct HT lead is going to No. 1 cylinder.
Fit remaining HT leads 1-3-4-2, working anti-clockwise around the distributor cap.

With that done, now check for sparks direct from the coil and at each plug. If no spark then identify why, but if all OK then either the engine will start or we move on to look at fuel.

[blue_cortina]

Thanks everyone for your replies - sorry I've been slow to respond. So, it sounds like the compression isn't terrible then. So, I tried it a few days ago and eventually it started and ran for a while. But I've had no luck since. It's really not happy to fire up, occasional cough but just won't catch.

Ignition - distributor was stripped a year or so ago and cleaned up. New (DrDistributor) Rotor arm, points, condenser, LT lead. New spark plug leads and plugs. Plugs set to 25 thou and Points to 15 thou. I believe the leads are in the right order and that the distributor angle is roughly right - see attached photo.

Timing - Set to 5deg (IIRC) before TDC statically.

Carburettor - stripped and cleaned, new service kit parts fitted (except float valve) - all new gaskets. Jet set 2 turns down as base setting. Needle nicely centred and piston falls easily. Carb oil topped up to level with 3-in-1. New petrol pipes and filtered fitted around pump. Pump ticks at first when ignition turned on after a few days as you'd expect. Petrol in float chamber.

Petrol I admit is now 6 months old - though I also had these issues 6 months ago when it was new, And have been waiting for the weather to improve and deal with other events in my life.

When car doesn't start I pulled a plug and believed I could smell petrol.

I believe that Moggies in general are really easy to start cars so I'm baffled as to what is going wrong. Never been this stuck trying to get a car to start.

I've you've got this far then thank you for your patience in reading this! Any help would be gratefully received as I've basically ran out of ideas and would dearly like to have a chance of driving the car I've spent the last two years trying to get road safe.

[philthehill]

Does the rotor arm point to No: 1 segment in the distributer cap when No: 1 piston is at TDC on the compression stroke.
The plug leads are fitted as per the firing order of 1, 3, 4, 2.

[simmitc]

As well as Phil's point, remove all plugs, one at a time, connect to their correct HT lead, wedge the plug to get a good earth, and crank the engine. Check that each plug does have a good spark.

Separately, disconnect the fuel pipe from the top of the carb and place in a container suitable for petrol. Do not attempt to start the car, but switch on the ignition and conform that the fuel pump clicks continuously and that petrol is being pumped. Switch off, reconnect pipe, and return petrol to the tank.

Report back.

[blue_cortina]

Weather has brightened up after a rainy morning here so went out and checked position of rotor arm when number 1 cylinder is on compression. I believe it is, here is my process. Take out No.1 spark plug. Hold thumb over hole whilst moving the engine with starting handle. Ensure that pressure is felt at the point at which timing mark on pulley is getting to timing mark on engine. If pressure is felt then both valves must be closed and If you see any bubbling around thumb then its in the right direction. I've attached three photos - timing mark alignment, rotor arm position and rocker position (not sure if that one helps).

After I'd put it all back together, I put the battery on a boost and got engine to turn over quickly and it coughed a couple of times but wouldn't catch and go.

Think I'll try and get some fresh fuel in the week just in-case, although it ran the other days on this fuel once it would actually catch and go.

[Bill_qaz]

Is the air intake and exhaust unrestricted ?
Is the choke working?
Have you tried a sniff of easy start or brake cleaner in the air intake

[blue_cortina]

As well as Phil's point, remove all plugs, one at a time, connect to their correct HT lead, wedge the plug to get a good earth, and crank the engine. Check that each plug does have a good spark.

Separately, disconnect the fuel pipe from the top of the carb and place in a container suitable for petrol. Do not attempt to start the car, but switch on the ignition and conform that the fuel pump clicks continuously and that petrol is being pumped. Switch off, reconnect pipe, and return petrol to the tank.

Report back.

So I've been back out there and disconnected the fuel pipe going to float chamber and put the end in a suitable catcher. Applied power to the pump and plenty of fuel came through.

I removed each plug in turn and with it pressed against a suitable earth turned over the engine and observed sparks. 1 and 2 were very good, 3 & 4 less so and I think the plugs were a bit oily. Cleaned them up and tried again and reasonable spark. Reassembled everything and turned engine again. I did cough and splutter a few times and it did try and run for a couple of seconds. It sounded lumpy/rough and basically not right, revved it a little to see if it would clear but just died. Tried again and similar and got what sounded like a little back fire - unburnt fuel? Gut feeling is plugs are oiling up and preventing a decent spark on all cylinders - but that's where I started with this thread and that might still be jumping to conclusions.

[blue_cortina]

Is the air intake and exhaust unrestricted ?
Is the choke working?
Have you tried a sniff of easy start or brake cleaner in the air intake

Air intake clear - I've tried it with and without the air filter tbh (even though that's new).

I believe the choke is working but will double check next time I'm out there, weather has turned so no more today. The cable certainly moves the appropriate part on the carb.

I have tried the brake cleaner approach in small amounts but made no difference, I too thought it might help give it a kick start onto working.

[les]

This is a long shot but a set of points I recently bought were faulty. The engine fired up initially but would not run, the cause was found to be the clearance between pivot point and the arm that is moved by the cam, being too tight, therefore the spring didn’t have the strength to return the arm, preventing the engine continually running, I bought the set of points from where you bought yours. However my experience may have been a one off. Maybe worth trying another set though !

[Bill_qaz]

Is the air intake and exhaust unrestricted ?
Is the choke working?
Have you tried a sniff of easy start or brake cleaner in the air intake

Air intake clear - I've tried it with and without the air filter tbh (even though that's new).

I believe the choke is working but will double check next time I'm out there, weather has turned so no more today. The cable certainly moves the appropriate part on the carb.

I have tried the brake cleaner approach in small amounts but made no difference, I too thought it might help give it a kick start onto working.

You didn't mentioned if you checked exhaust get someone to put hand over tail pipe while spinning engine.and see if you feel anything
You have checked the piston is free in the carburettor rises and falls ok
Usually even weak spark or low compression would at least cough on starter fluid.

[blue_cortina]

So, I finally got to work on the car again this weekend. I picked up a gallon of fresh fuel (sadly E10) and a new battery (075 from Halfords!). Tried to start - wouldn't start . I took all spark plugs out - rechecked the gaps and cleaned them - they seemed a little oily tbh. Turned engine over and it coughed and spluttered but caught and ran. It wasn't too happy but it was running. After letting it warm a little I started to blip the accelerator and it kinda backfired/misfired. It ran on fast tick-over until I got it somewhere near near up to temperature - the thermostat opening for the first time in a very long time. I turned it over and reset the the carb to base position.

I then did a compression test whilst it was still hot (with throttle open). After that I thought I'd try and start it again - but nothing - no go. I was puzzled as it had strarted so well. I stood there for a moment then laughed at myself - I'd not put the plug leads back on, I did that and it fired up.

Fresh with renewed success I pushed my luck - a quick drive round the block - interesting and scary but it did it. Longest drive in over two years.

Compression Test -
12/3/2023 (30/4/2023)
Cold Hot & Throttle Open
Cyl PSI PSI
1 135 128
2 135 138
3 130 130
4 140 134

[blue_cortina]

Quick update on this - Since the last post I've been trying to start the car every couple of days and I'm really pleased to say she started everytime without much effort.