2000sc Rougher than ever

I have played around with my sc for sometime. It has always sounded noisy and rough. For that reason I am reluctant to put the car on the road having concerns re. Its reliability. Recently however I decided to get stuck in and try and sort it out.
I always knew that my valve clearances were not correct and have had a number of tries at grinding the shims.I can now say that they are spot on (within tolerance anyway) This was done yesterday, and this morning I gave it a try. Yes you guessed it, as bad as ever if not worse. At first it would not run and sounded as if it was trying to run on one cylinder only. I managed to get it to run by moving the distributor ( electronic) but horrible to listen to and loads of vibration. I believe my valve timing is fine. What have I done or not done correctly. With the air filter removed it is possible to see petrol blowing back through the carb(not misfire). Would this indicate a sticking valve or incorrect ignition timing. Suggestions gratefully received
 
Did you recheck all the valve clearances after shimming them and refitting the cam?
I ask because the symptoms sound the same as the ones I got recently after having a "senior moment" and missing out a shim from an exhaust valve.
 
No I didn't but will pop into the garage and check that now.
I forgot to mention that prior to tackling the tappets job yesterday I carried out a compression test and all four cylinders were showing around 165psi
 
Hi, The final pressure looks good but it's half the story. How did it get there 2 or 3 'jumps' or a fair size one then a load of smaller one of say 10 or 15 pounds? Which could mean valves for example. Was it done wet or dry? Was the throttle held open?

Colin
 
The compression tests were carried out with my wife turning the key while I checked the gauge. Each cylinder was checked with one turn of around six seconds at a guess.All the plugs were removed but in all honesty I forgot to tell her to put the accelerator on the floor.
 
Willy. Re the valve clearances. I feel so daft after bragging that the tappets were spot on and all within tolerance, in fact they are nothing of the sort After taking the measurements and calculating the size of shim required yesterday, well you know the score the clearances are all to pot in fact two exhaust valves have no clearance whatsoever. I used one of those cheap (£4 at the car boot sale) digital micrometres which I have now chucked and ordered a decent one from Amazon....a bad workman blames his tools etc. but it is just so easy to blame someone or something for your own stupidity.
 
Oh dear, so you're going to have to do it all again. I do sympathise.
On mine, it wasn't zero clearance on the exhaust valve that caused fuel to blow out of the carb, it was just the opposite - so much clearance that the exhaust valve wasn't opening at all. All the compression then had to escape via the inlet valve the next time it opened. But that had taken an extreme act of stupidity to achieve!
 
Make sure the engine's stone cold when you check the valve clearances. I getting an accurate (consistent) reading with feeler gauges was tricky. I suspect a dial gauge and lifting each tappet in turn might be easier.
 
Will recheck the clearances this morning after the car has been in the garage overnight so should be cold. Am inclined to think you are correct regarding the dial gauge would be easier, will have a think about that bearing in mind that the imperial micrometre is due for delivery tomorrow.
Just a thought, I have always used galvanised 12mm. washers (10per bolt) for distance pieces when removing the camshaft bolts. Could that be a factor regarding my calculations for the most part always being wrong.
 
Whenever I have played around with the timing chain tensioner I put cloths in the chain housing. When I have played around with the valve clearances I put cloths in the chain housing. This morning I started to remove the centre camshaft bearing, the hardened washer slipped off the bolt, bounced on the cylinder head and straight into the timing chain housing...... no cloths. I couldn't see it in there and played around with a magnet on a piece of string for half an hour, shoving the magnet further down with a thin wooden stick, no good. Hopefully the washer will be in the sump...... Doesn't it make you want to spit.
 
Chances are very good it made it to the sump. I've made that mistake a few times, and every time the object has gone right through to the sump.

The only place it could lodge to cause damage would be to end up between one of the chainwheels and its timing chain. If you roll the engine over a couple or three revs by hand, both forwards and backwards, you'll find out quickly if it's caught somewhere. Good luck!

Yours
Vern
 
Found the washer in the sump.
Will leave the sump off until cam job done just in case. With a bit of luck should start messing with the shims tomorrow.
 
I have played around with my sc for sometime. It has always sounded noisy and rough. For that reason I am reluctant to put the car on the road having concerns re. Its reliability. Recently however I decided to get stuck in and try and sort it out.
I always knew that my valve clearances were not correct and have had a number of tries at grinding the shims.I can now say that they are spot on (within tolerance anyway) This was done yesterday, and this morning I gave it a try. Yes you guessed it, as bad as ever if not worse. At first it would not run and sounded as if it was trying to run on one cylinder only. I managed to get it to run by moving the distributor ( electronic) but horrible to listen to and loads of vibration. I believe my valve timing is fine. What have I done or not done correctly. With the air filter removed it is possible to see petrol blowing back through the carb(not misfire). Would this indicate a sticking valve or incorrect ignition timing. Suggestions gratefully received

Hi there,
I had a similar problem after rebuilding my Daimler/Jag 2.5 ltr v8, would not start and run, made dreadful noises . finally checked the distributor leads firing order, I had it 180 deg out.
I read the manual and found that in reading the manual , instructions were for looking forward from driving position, I had taken it to read as looking at the engine and thus installed the leas accordingly. silly old me, senior moment.
After installing the leads correctly it burst into life and ran sweetly for several years, before parting with it.
with your problem it could be something totally remote from my experience but its just my 2 bobs worth, and I felt that I had to pass on this information regardless of how silly it may sound. :cool:
good luck
Peter
 
A simple compression test will eveal it the issue is a valve sticking open. If you pull all the plugs and get someone to turn the engine over just puttiing your finger over the plug hole will tell you if the valves are sealing. If you get NO blowback (or nearly none)the air is coming in and out somewhere else, most likely a valve face. given there is no backfire I'd suspect its a inlet valve. But give Peter's check a go first as it is not uncommon and check that when the timing mark is lined up the rotor button is pointing at either number one pole or the one directly opposite then match that to the valve timing of number one cylinder. If its firing on Number one then that cylinder's valves should be on the back of the cam lobes
 
A simple compression test will eveal it the issue is a valve sticking open. If you pull all the plugs and get someone to turn the engine over just puttiing your finger over the plug hole will tell you if the valves are sealing. If you get NO blowback (or nearly none)the air is coming in and out somewhere else, most likely a valve face. given there is no backfire I'd suspect its a inlet valve. But give Peter's check a go first as it is not uncommon and check that when the timing mark is lined up the rotor button is pointing at either number one pole or the one directly opposite then match that to the valve timing of number one cylinder. If its firing on Number one then that cylinder's valves should be on the back of the cam lobes

Hi, See posts 3 - 5.

Colin
 
Thanks fellas
The plug leads are ok and the firing sequence with the rotor arm pointing to the correct cylinder seem fine.
I am trying to start a baseline and work from there to establish something that I know to be absolutely correct. That baseline is the valve clearances. I now have my tools, decent micrometre and a dial indicator so no excuses.
 
Peter
That Daimler Jag 2.5 V8 must have been terrific. I currently drive a 2002 rusty old S type4.2 V8 which is simply wonderful to drive but the bodywork and electronics are a nightmare, no engine problems though.......... maybe I shouldn't have said that.
 
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