Help. My engine runs 'lumpy'

VW Passat Estate 1800CL 1985
I took the head off and had it skimmed, adjusted the valve clearences with new shims and reassembled the engine. It starts but runs so 'lumpy' it shakes
the driver when ticking over. It isnt misfiring and it isnt slow to rev up. It's the same lumpiness you feel when the ignition timing is way too far advanced or when, as with old manual choke cars, the choke is left closed for too long. I've checked the valve timing as per the manual using the marks on the camshaft gear, fan belt pully and engine block. They all align correctely. I havent touched the carb except to remove and replace it and havent disturbed the ignition timing. Anyone have any ideas?
Many thanks Roger
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RD

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ukdodger via CarKB.com wrote:

Did you R&R the distributor? If so, did it go back in at 180 degrees off? I have seen that happen on other makes of car.
Stuart H. Jetta V Diesel '91 JDM Eunos Roadster
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Thanks Stuart but no I didnt touch the distributor.
Cheers Roger
Stuart H. wrote:

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RD

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Maybe forgot a vac. hose?
SFC

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Thanks SFC. But I didnt disturb the vac hoses. I was careful not to because the last time I did and it took me weeks to figure out which one was in the wrong place!!!
Roger
SFC wrote:

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well disturb the ign. timing, or at least check it. ;-)
check the carb to make sure the fuel does not overflow into the throat. Fuel might overflow in pulses.
check the vacuum too and post results. did you check the compression on the cylinders after the engine was reassembled?

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Thanks Dave. No I didnt check the compression. Also I forgot to add that I ground the valves in too. Hence the new shims required for the clearences. If it is a fault with the compression why would that result in this lumpiness. Cheers for your help.
Roger
dave AKA vwdoc1 wrote:

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Lumpiness could be caused by a cylinder not "pulling its weight" and the balance is off. So 1, 4, 2 might be pulling strong and #3 is weak. Like if you sprained your right ankle and you tried to run.
When an engine running problem occurs, it can sometimes help to determine the health of the engine before checking everything else. I have seen at least 1 watercooled engines with 1 weak or bad cylinder. Hard as heck trying to get it to pass the emissions test. 8^)

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Thanks Dave I'll check that out.
Roger
dave AKA vwdoc1 wrote:

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