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MGB 1982 MG B 1.8L. Timing?

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SuperDuty

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Actually my wife's car inherited from her dad, I think the odometer has rolled over at least twice. Motor was pretty dirty so I sprayed on engine cleaner and washes it down with just the hose to find a coolant leak. Bad hose, so I replaced both. Now it runs super rough and sounds like it's missing. This makes no sense. I let it sit for a week, started it up, let it warm up and took it for a hard test drive, no improvement so I threw a timing light on it and it's retarded past the marks. It looks like there is a bolt holding a collar at the base of the distributor that I can loosen and set it to TDC I hesitate to do this since it was running fine before. All I did was wash it. 1. Can anyone confirm this bolt crammed up against the block is the one I loosen? 2. Car had a full tune up including cap, rotor, plugs and wires. 3. Is there something I'm missing? I've timed American cars and have the wrench but the English cars are new ro me
 

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Hi Super Duty. You posted this is the Forum Happenings forum. I'm going to move you post to the MG forum (I'm guessing this is an MGB?). I'll leave a redirect in the Forum Happenings forum for a while. If you're reading this now, you are in the MG forum.
Cheers,
Basil
 
Is the timing mark on the balancer correct? If the rubber seperated, you will never get the correct timing. Try this. With chalk or white out, mark the outer and inner rings. Drive a bit and see if the marks are still in the same place.
 
In answer to your question; yes, by loosening the referenced pinch bolt shown in the photograph, you will be able to rotate the distributor to adjust the ignition timing.



i
 
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Gong back to the first post - Did the "rough engine" problem start just after you washed down the engine, and before you had the tune-up? If so, there's likely moisture still inside the distributor, spark plug caps, coil, etc.
 
Whenever I've washed down an engine, I always cover all the electronics with plastic bags and run the engine while doing the wash. If it begins to sputter, I know it's time to stop the wash.
 
Basil said:
Hi Super Duty. You posted this is the Forum Happenings forum. I'm going to move you post to the MG forum (I'm guessing this is an MGB?). I'll leave a redirect in the Forum Happenings forum for a while. If you're reading this now, you are in the MG forum.
Cheers,
Basil
Click to expand...
Thank you
 
NutmegCT said:
Gong back to the first post - Did the "rough engine" problem start just after you washed down the engine, and before you had the tune-up? If so, there's likely moisture still inside the distributor, spark plug caps, coil, etc.
Click to expand...
Correct and thank you I'll look deeper into that but weeks later it hasn't dried out?
 
maynard said:
Is the timing mark on the balancer correct? If the rubber seperated, you will never get the correct timing. Try this. With chalk or white out, mark the outer and inner rings. Drive a bit and see if the marks are still in the same place.
Click to expand...
I need to do a little homework and figure out what the balancer even is honestly. Searching the internet now
 
The balancer is bonded to the crankshaft pulley; it has the timing marks that you align with the pointer on the engine block.
 
Its real easy on these cars to check the alignment of the timing mark - just pop the #1 plug out and use a long thin instrument of some sort to feel the piston moving as you manually rotate the engine (with the battery disconnected if you want to be sure it doesn't accidentally fire off). A lot of people use a screwdriver, I like to use a coffee stir stick or a wooden chopstick so there is no risk of scratching a cylinder wall. When the piston is all the way at the top, see if the timing mark is close to the 0 degree line. If not, use a paint marker or something to indicate 0 degrees and plan on getting a new harmonic balancer at some point.
 
I changed mine (it had not slipped, but the rubber was clearly starting to get dry and cracked) - it takes a really big socket and a long wrench or impact and possibly a puller tool depending on how long/rusty its been on there. The nut torques to something like 80 ft pounds on reinstall and there is a locking tab/plate that should be replaced when you do it. And don't lose the little half-moon keyway thing that holds it in alignment. If you are doing it with the motor in the car, it gets a little more involved (probably plan on pulling the radiator out and unbolting the front motor mounts, you will likely have to lift up slightly on the engine from underneath to get clearance from the steering rack). My engine was out and on a stand, took all of 15 minutes in that state.

Before even going to that point, I'd verify the TCD position and get the timing sorted first. No point in going through all that for nothing. You can easily check the timing by painting your own mark at the real TDC if it has slipped, and deal with it later. And it is likely to be fine - the slippage happens occasionally but it isn't a super-common problem. It still sounds like something just got wet - I'd pull the cap and rotor, dry everything out real good (especially the points and condensor) and then start troubleshooting from there. These engines are crazy-simple, a lot easier to troubleshoot than anything with a computer...
 
YakkoWarner said:
Its real easy on these cars to check the alignment of the timing mark - just pop the #1 plug out and use a long thin instrument of some sort to feel the piston moving as you manually rotate the engine (with the battery disconnected if you want to be sure it doesn't accidentally fire off). A lot of people use a screwdriver, I like to use a coffee stir stick or a wooden chopstick so there is no risk of scratching a cylinder wall. When the piston is all the way at the top, see if the timing mark is close to the 0 degree line. If not, use a paint marker or something to indicate 0 degrees and plan on getting a new harmonic balancer at some point.
Click to expand...
One must remember that the piston comes up to TDC twice for every revolution of the crankshaft and distributor. Make sure TDC is on the top of the compression/power stroke in lieu of the exhaust stroke. You can do this by witnessing the position of the #1&2 rocker arms which should both be loose in lieu of under tension when the piston reaches the top of the cylinder, and also by looking at the position of the distributor rotor. In a correctly timed engine, TDC of the compression/power stroke occurs when the rotor is pointed somewhere near the 1 o'clock position.
 
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Scargo said:
One must remember that the piston comes up to TDC twice for every revolution of the crankshaft and distributor. Make sure TDC is on the top of the compression/power stroke in lieu of the exhaust stroke. You can do this by witnessing the position of the #1&2 rocker arms which should both be loose in lieu of under tension when the piston reaches the top of the cylinder, and also by looking at the position of the distributor rotor. In a correctly timed engine, TDC of the compression/power stroke occurs when the rotor is pointed somewhere near the 1 o'clock position.
Click to expand...

This is certainly true for the distributor and camshaft, which turn at 1/2 the speed of the crankshaft. The pistons however, do in fact move up and down at the same speed as the crankshaft, so for purposes of verifying the timing marks it won't matter which stroke the piston is on.
 
Ah, right you are. I was assuming he was going straight to ignition timing, and lost my train of thought relative to the crank issue. Brain-fade on my part. Thanks for setting me straight.
 
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