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MGB will not start

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Jwh4996 Joe Holland
Market drayton, Shropshire, UK   GBR
I have been gifted a 1970 MGB roadster by my granddad that has been stored well for roughly 15 years. I have changed all fluids, put in a new fuel tank, completely stripped the carbs and cleaned them, put in new fuel lines and fuel pump (aftermarket facet type) and I have also bought a new coil, HT leads, new plugs, and I have replaced the points and condenser (25D). I have an accuspark electronic ignition module but I have been told they are not best in terms of working out timing and getting The car running, so I have opted for points in the mean time. The points have been gapped correctly, there is a good spark on all cylinders, I have fuel running to the carbs and it is getting into the cylinders from the carbs (the plugs are getting wet), and I have also set the static timing correctly (as far as I am aware, as I am pretty new to this) and I have even tried the timing 180 degrees out. The car has sort of spluttered slightly at points, but it does not seem to even be attempting to fire, and it will definitely not run, it seems to be behaving as if there is no spark even though there clearly is!! There is a fair bit of pressure intermittently being thrown back out of the throat of the carbs too when cranking over. Starter fluid is also not doing anything at all. I really do feel like I am banging my head against a wall and any help would be greatly appreciated as I am at a complete loss! Could the carbs be set so badly it won't even nearly run? Could it still be timing?

Many thanks in advance

Joe

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dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
Welcome to the forum, Joe, and congrats on your "new" car... thumbs up

Almost certainly timing is your problem.

First, triple-check the firing order by way of the spark plug wires in the distributor cap. Cylinders are numbered 1-4, front to back. Wires in the cap should be 1-3-4-2 anti-clockwise. Make sure they are correct. Normally the number 1 spark plug wire goes into the distributor cap at about the 1 o'clock position.

If you can get the engine where it tries to fire, loosen the pinch bolt that clamps the distributor, and try rotating the distributor back and forth while a helper cranks the engine. There's a good chance you'll find a spot where it'll run. If not, try moving all the spark plug wires one tower counterclockwise and try again. If no joy, move 'em again and try again. One of these combinations should get the engine to run until you can set the ignition timing properly.

Try this procedure above. If no joy, let us know and we can walk you through setting the static ignition timing,which is more precise than the trial-and-error method above. But the method above should get you going...

Dick



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Jtmgb Avatar
Jtmgb Silver Member John T
Gainesville, Georgia, USA   USA
1968 MG MGB GT "CASH MONEY"
1972 MG MGB
1972 MG MGB GT "Dr. J"
1972 MG MGB GT "Ruby"    & more
Fuel spitting out of the carbs says that valves that should be closed are open at the wrong time. I would check the actual wiring at the cap pull the cap off and verify that the rotor and the timing marks on crank pulley are in correct position . Worst case is that the valve timing is off. Removing the timing cover and checking the cam and crank positions are not hard just a .....PITA..... I,ve heard all that fluff about accuspark ignition in just about every case , when there is a choice between mechanical and electronic . Well let's just say every auto manufacturer in the world has gone electronic.

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Jwh4996 Joe Holland
Market drayton, Shropshire, UK   GBR
Hi dick, thankyou for the welcome! I have set the static timing for 10 degrees before top dead centre on the compression stroke of cylinder #1 using a test lamp, checking for when the lamp just turns off/on. I have done it many many times over and over, I have moved the distributor slightly either way and still nothing has come of it! sad smiley the only thing I can see that is definitely odd, is that when the engine is at 10 degrees before TDC on cylinder #1, the distributor rotor arm is poInting at about 7 oclock, not 1 o'clock. To account for this I obviously swapped the HT leads round to match and ensured they were in the correct firing order. What do you think this means? My distributor shaft cannot be rotated through 180 degrees as the key at the bottom is offset slightly so it only enters into the engine in one single direction. Does this mean that my cam timing is off? I have attached a photo showing (roughly) the position of the rotor arm when the engine is 10 degrees before TDC on the compression stroke on cylinder #1.

Many thanks

Joe



Edited 1 time(s). Last edit at 2017-06-18 12:41 PM by Jwh4996.


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Bruce Cunha Avatar
placerville, California, USA   USA
1950 MG TD
1967 MG MGB GT
1979 Triumph 1500 ~ For Sale ! ~
1986 Honda Street
I am always leary of tearing things apart until you have done all the basics. You have fuel, you have spark, but do you have enough compression for it to fire? I did not see in the posting that you did a compression test. Vehicle being stored for 15 years would beg the question of why it was stored? Also, the valves can gum up and stick.

Do a compression test prior to anything else. The distributor can only go in one way, so it is as simple as assuring you are on TDC compression stroke and then put #1 wire to where the rotor is and wire around the cap from there.



Bruce E. Cunha

dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
Joe,

If you're certain that number 1 is in firing position on its compression stroke, then someone in the past has installed the distributor drive gear, down in the block, out of position. No matter. If number 1 is indeed in firing position, then just put number 1 spark plug wire in the distributor cap at the 7 o'clock position and put the rest in proper firing order, 1-3-4-2, and be sure they're anti-clockwise.

If you have a timing light, you might check the dynamic timing while a helper cranks the engine to confirm the timing. If the timing is indeed correct, or even close, the engine should run.

If the spark plugs are all wet, smell them to see if they're wet with fuel. You might try a fresh set of plugs, since these may be so fouled they won't sustain combustion. And do try having a helper crank the engine while you hold the carburetor pistons up to see if that helps. You could be experiencing a flooding condition from all the efforts to get it running...

Dick

In reply to # 3534852 by Jwh4996 Hi dick, thankyou for the welcome! I have set the static timing for 10 degrees before top dead centre on the compression stroke of cylinder #1 using a test lamp, checking for when the lamp just turns off/on. I have done it many many times over and over, I have moved the distributor slightly either way and still nothing has come of it! sad smiley the only thing I can see that is definitely odd, is that when the engine is at 10 degrees before TDC on cylinder #1, the distributor rotor arm is poInting at about 7 oclock, not 1 o'clock. To account for this I obviously swapped the HT leads round to match and ensured they were in the correct firing order. What do you think this means? My distributor shaft cannot be rotated through 180 degrees as the key at the bottom is offset slightly so it only enters into the engine in one single direction. Does this mean that my cam timing is off? I have attached a photo showing (roughly) the position of the rotor arm when the engine is 10 degrees before TDC on the compression stroke on cylinder #1.

Many thanks

Joe



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Jwh4996 Joe Holland
Market drayton, Shropshire, UK   GBR
I have done the above mentioned things, in terms of setting The number one lead at the 7 oclock position, and still no luck at all. If the distributor is loosened and turned anti-clockwise (quite a lot) the engine does seem to ignite some fuel, get a few intermittent pops and bangs coming from the exhaust, but still the engine is not catching and firing, it just isn't 'there'. When I rotated the distributor to the right (quite a lot) is began backfiring out of the carbs intermittently. Do you have any ideas from this information?

Many thanks

Joe

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RAY 67 TOURER Avatar
RAY 67 TOURER Ray Marloff
Fort Bragg, CA, USA   USA
1967 MG MGB "My Girl"
Try moving the ignition wires one terminal counterclockwise. Sounds like you're on the right track. RAY

Jwh4996 Joe Holland
Market drayton, Shropshire, UK   GBR
Hi Ray, I tried this earlier too, and still no luck. Again I had intermittent popping and banging when cranking the engine over, but no firing up of the engine. Do you think it could be the cam timing?

Joe

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dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
Are you really, really sure the plug wires are installed in the proper order, 1-3-4-2 anti-clockwise?

Dick



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

Jwh4996 Joe Holland
Market drayton, Shropshire, UK   GBR
I am 100% sure, I have quadruple checked

Thanks

Joe

Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
Pull the dashpots and measure the jet height. Start at .050.

Double check the float heights.

Wet plugs and raw fuel spitting out the carbs sounds wrong.



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bencii Ben Colpitts
Mansfield, Ohio, USA   USA
1966 MG MGB
Not sure if anyone has already mentioned this, but have you pulled the valve cover and checked for stuck valves? A compression test is the quickest way to see if this might be your problem. If you don't have a tester you might need to remove spark plugs to make turning engine by hand easier. Watch each valve to make sure it is closing.

Jwh4996 Joe Holland
Market drayton, Shropshire, UK   GBR
Hi guys I have solved the problem and got her fired up today! Compression was fairly low and it turns out some clever person in the past had adjusted the rocker clearances so low they were barely existent. I assume this was causing the valves to not close completely causing lower compression and therefore no firing up? Anyway, after adjusting the rocker clearances to the correct levels, the problem was solved and she is now alive. Now to fix all the other problems that have developed during its 25 years off the road!

Joe

RAY 67 TOURER Avatar
RAY 67 TOURER Ray Marloff
Fort Bragg, CA, USA   USA
1967 MG MGB "My Girl"
Well, at least the repair cost was minimal. RAY

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