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MG MGA - Engine starting problems

I had the engine running great on the chisie. i then disassembled some of it to put the body on. Now It's back together and will not start. It is trying to catch but starts to backfire. I have checked the static timing 10 times. #1 piston all the way up, rotor pointing at #1 wire, perfect gap in points, and set 7 degrees BTDC. Removed and cleaned plugs. they show carbon build up and are very wet. but they are sparking when checked. To me it sounds like the timing is off but I checked over and over. Aggggg completed frustrated Help!
Bill R

air filters upside down?
Tom

You may have got the firing order wrong on reassembly.

Steve
Steve Gyles

Is the petrol (gasoline?) stale? Modern fuels "go off" very quickly!
Barry Bahnisch

The fuel is the same as when it ran great and I checked the flow of gas up to the carbs.

I am sure of the firing order because my wires have the little number rings on them. Although, I must say that is what it sounds like while trying to start!

The filters I will check again but I remember making a note of that when I installed.
Bill R

Bill

Re firing order, did you remove the distributor after you initially had it running? It is possible to install the distributor with its shaft 180 out. Worth checking that with the No.1 piston on its firing stroke that the rotor arm is pointing at the cap terminal with your No.1 marked HT lead.

Firing order 1-3-4-2 working anti-clockwise round the cap from you No.1 lead.

Steve
Steve Gyles

Steve I Did not move the distributer other than to loosen the clamp for the timing. I am pretty confident that it is correct because the Vacume advance is were it should be and my rotor is pointing at 1 o'clock towards the #1 wire
I did remove the Carberators for the install so I may pull them off again and see if somthing is hanging up one of them. The symtoms are that it is just barely trying to start and then start backfiring with a "Mist" blowing out of the air filters. But it just will not start!
Bill R

Bill,
Is this engine a fresh rebuild? If it is, one possibility is that after running the engine in on the chassis, heating it up and letting it cool down, you've got a tight valve guide causing a valve to hang up. This sometimes happens on rebuilt heads. Just a thought.

Good luck,
GTF
G. Foster

Thanks G., I ran home and checked that and it was fine.
I also removed the air filters and eliminated the possibility of being upside down.
Checked the timing again to see if maybe I was not on the compression stroke. Bothe valves were properly loose at TDC with rotor pointed at #1 plug line.
I also removed the plugs and checked the plugs and they are all firing a nice spark.
I then poured a little gas down each cylinder and replace the plugs and tried to start. Nothing!
Per Barney's site I checked the compression in each cylinder and came up with a good 165 lb on all 4.
For Kicks I even relocated the plug wires to were it would be at 180 degrees out. Did'nt work!

All testing still results in it trying to start but sputtering and back firing

I am completely flustered! Don't know what else I can do as far as testing.
Bill R

The backfiring really seems to point towards ignition problems rather than fuel supply. You might try checking the distributor cap and rotor for cracks and if the active (coil) side of the points are not electrically shorting to ground or arcing - although the fact that you are getting a spark at the plugs eliminates a dead short to ground.

Steve
Steve Brandt

1. Pull the choke RIGHT out
then try
2, Replace the condensor
if that doesnt work
3. Try connecting the ignition wires 180 degrees out
dominic clancy

If you have spark then it should be either cap or rotor or even both. Are you sure that both carburettors are bolted up tight and the throttle is opening. There is not much else. I would also replace the plugs as they can be too fouled to run. change them first.
Sandy
Sandy Sanders

Like Sandy said, I would try replacing the plugs. Just because they look fine and will spark when out of the engine doesn't mean they will fire correctly under compression in the engine. I had a problem where it would not start in the spring after sitting all winter. I tried everything. The plugs looked good and would spark when cranked outside the engine. I finally replaced them and it fired right up.

Jeff Schultz

Bill,
You might also try cranking it over in the dark. Check the distributor and plug connections to see if any arcing is occurring. As Dominic suggests, the condensor is also a suspect.

This has got to be something simple...

GTF
G T Foster

Just a stupid thought re timing. Assuming you have the standard MGA timing cover with the timing marks under the pulley. With the confusion of now having to hold you head almost upside down to see the timing marks now the body is on, have you by any chance timed the engine to the wrong end of the pointers? i.e. The left pointer, when viewed from the front is TDC. Could you have timed it against the right hand pointer?

I know the TDC pointer is longer than the others, but anything is possible.

Steve
Steve Gyles

FIXED IT!
I am almost too embarrassed to tell you all. But, you all deserve a good laugh even if it's at my expense for all your help!
Cheers to Steve, you nailed it!

Remember me mentioning those silly little yellow number rings that you put on the plug wires! Well, when I first installed them I sequenced them in order from front to back. 1234. When I reinstalled the cap and wires, I sequenced them, per those number rings, in the firing order 1342.
So the #1 plug was right and all the rest were wrong! Go ahead and laugh! I am still shaken my head and laughing at myself!
However on the bright side I got to take it on its first maiden voyage with my daughter who's been helping me!
See pic below



WMR Bill

Bill

We have all done something similar. Glad you sorted it quickly.

You have just maintained my average of getting one right a year.

Car looking good. How long til you finish?

Steve
Steve Gyles

Thanks again Steve! As well as everybody else. I hope to have my Re-chromed front bumper and windshield frame back in a few weeks. Meanwhile I will continue working out the bugs! (Turn signal not working) and completing the rails and interior.


WMR Bill

This thread was discussed between 12/07/2007 and 13/07/2007

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