valve seat recession or poorly set up gaps???

Pilkie

Pilkie

Active Member
Hi all.

As Connor is still not to my mind performing as I think he should,I have done a recheck of all the bits ive tinkered with to wake him from his 17yr slumber.
The only thing I can think of that is causing the lack of power is the valve gaps are all a little tight.
Ive done a compression check and theres no obvious probs there.
The figures for the techno minded,and those who know the 4 pot 2L motors foibles are.
1,,inl .006 exh .009
2,,inl .007 exh .010
3,,inl .008 exh .011
4,,inl .007 exh .012
Cold they should be;
inlet .008-010
exh .013-.015
Is this everso slightly valves on the tight side enough to affect its top end grunt,as bottom end performance up to 60 is very smooth and about right?
And with all the messing about,re-setting up ive been doing it seems to be returning about 30mpg!
Now this is either down to the fabled valve seat recession caused by using unleaded back in the late 80's early 90's or badly set up some time in its past.
Fortunately tomorrow Nick D will be having a test drive and can let me know what he thinks of it.
In the mean time any of your thoughts,experiences are welcome.

Dave,,
 
I wouldn't have thought the gaps being tight in themselves would cause a problem , and if your compressions are OK the valve seats can't be that bad
Ma\ybe you're just expecting too much from the old girl ?
 
A cylinder leakage test will show if they are being kept open :)

Told you you'd find it slow :wink:
 
With valve seat recession the valves can still be seated perfect and the compression can be ok,but as the gap is too small the valves open and close to quick!!
1.. its not sucking enough fuel/air in to make a proper bang at the topend thus affecting acceleration and top end performance.
2.. the exh gasses cant escape quick enough causing engine choking like sticking your hand over the exhaust pipe!!
If just 1 or 2 were a bit tight it may not make much difference,but when all of them are tight it affects the pistons suck,bang,blow!
 
I'd be shocked if the 2 thou away from recomended tollerance would cause that on the inlet. The exhausts are worse in fairness.
If a leakage test showed all good I'd just do the tappets to start with. But that's me. Compression tests never give you the whole story IMO :)
 
If they dont open wide enough and for long enough you dont get enough mix for a big enough bang.
In my experience with easily "screw" adjusted tappets,its a very fine line between ok and not ok,and even a thou can affect things!
Too big a gap and they dont open quick and long enough,too small and its open and shut too fast!
Just like ign timing,, just 1 degree can make all the difference!!
Anyway will see what tomorrow brings at the show.
 
Hi, it is not just the final pressure you are looking at. If it was valve problems the
gauge would jump to 80/100 pounds say in two big jumps and then go to 180 in a
series of 10 pounds steps. So you need to read the gauge as it is doing it to get
the full picture.

As GrimV8 says it will feel slow, the performance figures may be similar to the V8
but the delivery is different. I know I found my 2200 TC harder work than all my
V8s. Colin
 
I would know if there is a valve leaking or even a piston ring problem,as ive done 2 or 3 tests and a wet and dry test,and watched the readings as they go up,and all is well there!!!
I dont expect it to perform anywhere near how my V8 does.
The power delivery seems fine up to a point,and that point is less than I would expect it to be.
There may not be a problem,and that is how they are,but my gut and 35 yrs mechanical experience tell me there is something amiss!
Just got to explore all avenues!!
 
colnerov said:
As GrimV8 says it will feel slow, the performance figures may be similar to the V8
but the delivery is different. I know I found my 2200 TC harder work than all my
V8s. Colin
Click to expand...
2200TCs are a rocket ship compared to a 2000 Auto :D
Even the guys that worked at seagrave road reckoned the 2000 lump just didn't suit the auto set up. The ones I worked on when they were current were slow :|
 
SC does stand for "SlowCoach" after all!

Once all the engine settings are correct they can still be very slow, but one of the main factors for that on the auto is the kickdown cable setting. They are often set up with the pressures on the low side, and that makes them really sluggish. Unfortunately you have to be careful not to go too far when bumping them up, as too high pressures increase the load on the flexplate.
 
The gearbox had a full overhaul about 2k miles before it was laid up 17 yrs ago.
However,it could of been set up wrong, but it is working brilliantly smooth and does all gears,and kickdown as it should.
I had thought at one point that it was due to the brakes binding,and that didnt help,but they are all free running now.
 
I would adjust the clearances before you burn an exhaust valve. I have an Excel spreadsheet to help calculate the shims you need.PM me if you are interested.

I own both a 2000 automatic and a 2000 TC. Driving onto a busy freeway in a 2000 automatic you put your foot down flat to the floor as hard you as you can and hope that the thing accelerates fast enough to merge into traffic. I also avoid freeway entrances on an uphill grade in this car. Thankfully that car is in a state with only one freeway, and 2 express ways!

My 2000 TC on the otherhand has plenty of get up and go for merging onto a freeway. It gets up to highway speed quite quickly, and keeps up with modern cars very well.

As for drive plates I have broken 2 of them. Keep one in your boot and you will never break another driveplate again. I had custom headers added to my 2000 automatic and this has helped a bit. However when you do break a driveplate you can experience the Rover being the nicest car you can ever wait for a tow truck in! People have commented on how nice my Rover is as it was pulled up onto a tilt tray truck.

James.
 
Thanks for the spreadsheet offer James,but a simple pen and paper,and a little basic maths! :wink:
And its done quicker than waiting for my PC to warm up and loading the info! :)
I am getting a nice sounding,smooth 2200TC engine soon as a back up,so if I do keep the car I will have the option of upgrading for extra power,or,if I decide to sell it once the V8 has had its repaint and refurb,I can offer the engine to the new owner if they want it!
 
I don't think you'd get good compressions with valve seat recession as it's transferring bits of molten valve seat to the valve
No doubt Harvey will confirm
 
If the valves/seats were in meltdown mode, I suspect it wouldnt run!
Just checking my info and 4 star was still widely available in 1993,so I doubt therefore the problem is caused by u/l fuel,so must be either general even wear and tear,or set up wrong at some point.
At least I can easily replace the shims without removing the head,and if that doesnt work I will do a complete decoke and relap the valves.
 
chrisyork said:
I take it the run up to Rugeley didn't improve Connor then, Dave?

Nope! It didnt get above 70 even downhill,nor coming back either! :(
Click to expand...
DaveHerns said:
What was Nick Dunning's opinion on it's performance ?
Click to expand...

Unfortunately Nick was busy, so he didnt get a chance to have a spin.
 
Is the distributer working correctly? I assume the engine runs smoothely with no missfires, so I would be looking at either not enough fuel getting in caused by a weak fuel pump, or the vacuum advance not advancing properly. Both of these could be caused by a prolonged period of innactivity as yours has had. Both should be easy to check by susbsituting parts with known good parts.
 
You must log in or register to reply here.
Back
Top