struggling for power

Starting with no clearances makes things more difficult. Starting with the biggest shim is not a good idea as that will guarantee no clearance. You have two ways to proceed, either measure all the shims that are fitted now then decrease the size of the shim by the maximum clearance. You may end up doing this several times before you get a reading.
Alternatively fit the smallest shim or shims that just stand proud of the valve spring top collar. This should guarantee a clearance (even though it may be massive) and so you should be able to do the re shimming in one go.

As for the valve seats they should last equally as long using unleaded as they did with 4star. They were always burning out valves and dropping seats when we had better fuel.
 
I meant starting with the large shims, alone. There is a large and small per valve.The smalls are in the neighborhood of .08
or so.
Using the dial method, I might get an approx starting point .

Dick West
 
You'll probably find that the larger of the two shims on their own will sit lower than the valve spring top collar, so the cam follower (tappet) won't be resting on the shim.
 
I'd still say that on the majority of engines you adjust the valve clearances because the gaps have increased due to wear on the cam / followers etc
If the gaps close up in service , something is wrong eg the valves are being eroded and sinking into their seats
 
As we're talking Rover, you have to remember that as the clearances are not in the schedule to be checked on a service, they may (and do) go for 80k miles and more without ever being checked. Over that milage it's not unreasonable to expect that the valve seat wear could close up the clearance by say 5thou, which on an inlet would leave a clearance of 3thou which would compromise performance, but it doesn't mean the head needs to come off. And if you're fitting a s/h head, how do you know that one is any better than the one you've already got?
 
But if you've got issues with closed up clearances and been running the engine for a period of time, you can be fairly sure you'll have some form of damage to the valve seat, maybe burning, maybe a heavy layer of carbon, making it a good idea to remove the head and grind the valves in anyway. Although you might as well try re-shimming the tappets first to see if it sorts the problem.
 
As long as you've got some clearance so the valve isn't being held open there should be no damage to the seat, carbon build up should be no worse than normal. If we were talking about a pushrod Ford would we be saying "its got a tight valve clearance, pull the head off!" I doubt it, You would adjust the clearances. The Rover is a bit more involved but still simple enough to do if you know what you're doing.
 
Is there a more difficult engine to adjust the valves on?
The jag was a piece of cake, compared to this, even though it also uses shims.
Dick West
 
I think a lot of it is what you get used to, both the P6 and Jag are ohc with bucket tappets with the shims underneath so they both should be as easy as one another, but I'd do the Rover every time because that's what I've spent most of my time doing. As for cars that are more difficult, initially I always found the SD1 2300/2600 a problem, the shims under the rockers were ok because you could slide those in, but the ones under the camshaft needed the carrier to be removed and every time you re-fitted it, it settled down on the dowels in a different place, so altering the readings. After doing a few you could work round it but they were still a pain!
Personally I like the Rover V8 the best. :D
 
Got a new idea on setting these shims from scratch:

When the Spacers are installed, and all the "buckets" and shims removed, the cam will freely rotate without hitting anything.

Therefore to get an initial setting on any valve, leave out all the other buckets, rotate the cam so the low part is on the valve you are adjusting, and have a go at it.

This can be done for all eight, and should be pretty close when adding back the cam bearing caps and retorquing.

Gonna try it anyway.

Dick West
 
I can't say I've ever tried that, and so wouldn't be sure that the camshaft will rotate without hitting the tops of the other valves. When you undo the head bolts that carrier always seems to be forced up a long way. I await the outcome with interest.
 
Just been reading the procedure in the Haynes manual...
To cut a very long story short, you measure the current gaps, remove the cam and tappets, then remove the shims, measure them and then obtain the correct shims to make the gap correct, then replace it all. Sounds dead easy.. NOT !
Anybody for a hydraulic tappet conversion ? :D
 
The thing is it REALLY is that easy, if you can use a micrometer and add and subtract that's all there is to it. As I said before it does become more difficult if you have no clearances to start with, but only because you have to go through the procedure several times.
 
The new procedure DOES work. Now the only problem I have is probably the same for any individual owner: Who happens to own a complete set of shims? They will be hard to find on this side of the pond. I have scavenged shims from my other two parts engines, but can see I might have to do some grinding, as I don't have enough of the right combinations.

Dick West
 
sounds like you're making progress. Shims are a problem as it tends to be the same ones need more often than others. I had a massive tin full of them, but still ended up not having the ones I needed.
I'm sure what you would need can still be found this side of the pond and even in the unlikely event you needed two shims for every valve it wouldn't cost a fortune to get them shipped over to you. Just depends how much of a hurry you're in.
I have to say if I ever do another set starting with zero clearance, I'm going to try your method.
 
Did someone change the language while I was gone cos you all might as well be talking dutch!

What Russ says sounds pretty spot on,nothing on the hills,no go in 3rd or 4th and unless its downhill 60mph at a push.

Was all set to play with the carb but messing about with valves and stuff sounds really scary.Realisticly is it something a novice like myself should touch or should I be looking to take it somewhere?

I'm in Telford,Shropshire,can anybody recommend anyone in the region?
 
Before jumping to conclusions, a good place to start is with a compression check. Good results on this will save you worrying about rings and valves.
Then go on to ignition and carbs.

Dick West
 
Quick update,took the car to my usual mechanic and at first look,he had a drive to,he thinks its only running on three cylinders.He's going to do a compression check this week and we'll take it from there.Will let you know how i get on.
 
HELP

Just had the compression test done and this is what my man had to say:

no. 3,4+5 clearances are less than 0.25mm and he thinks this has burnt the valves.

1st run no.1 165psi,no.2 155psi,no.3 145psi,no.4 150psi
2nd run 165psi 160psi 145psi 150psi

What the hell do i do now?He thinks i should just get rid of the car but theres no way i'm doing that!He thinks it would cost to much to replace the head and i'm not flash with the cash at the mo.

Can anyone suggest anything?

Thanks
 
Fitting new valves seats shouldn't cost that much, ring up some engineering shops and get an idea of price - those, plus new valves and you can run on unleaded without worry

Thats assuming 4 cylinders have alloy heads with seat inserts ?


Or alternatively keep your eye open for a spare head, Ian must have some for sale and use an additive from then on

Cost of a decoke set can't be more that £15
 
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