Exhaust valves.

[j_radcliffe]

Looking at my 1966 parts catalogue (2000 SC) it shows 2 part numbers for exhaust valves, one for 4 speed models and the other for automatics.
Does anyone know what the difference is? I suspect that they started running the stellite valves first in the automatics, as they tend to run warmer, and used up the older (and softer) valves in the 4 speed models. If anyone has a later parts catalogue perhaps they could have a look for me.

I have a good stock of 2000 TC Nimonic exhaust valves. The part number for the seats and the valve guides are the same on both the 2000 TC, and SC. The springs are different, and I believe that SC valves are meant to rotate as they close. Is there any reason that I could not use a TC exhaust valve in an SC head? I think it would work fine, and the TC valves being very hard would be better suited to the lead free petrol which we use today.


James.

 

[darth sidious]

.......... and the TC valves being very hard would be better suited to the lead free petrol which we use today.


James.

Yet I get the impression that it's the 2000TC heads, valves etc that seem to suffer the most with present-day unleaded petrol...

 

[Keith Coman]

Data points:

1. I have run a TC for nearly 10 years on SC exhaust valves.

2. A recent cylinderhead rebuild [occasioned by a dropped valve seat] revealed these valves to be in pristine condition. [The original TC inlets were also fine although they have a gazillion more miles on them and may well be original Class of '69ers.]

3. NZ offers 95 octane ULP of sometimes uneven quality.

4. A squirt of upper cylinder lubricant [Morays - which is probably much the same as Redex] is added to the petrol after every refill. [Revs are kept to conservative levels plus the legal maximum road speed in NZ is a mere 60 mph.]

 

[darth sidious]

Data points:

1. I have run a TC for nearly 10 years on SC exhaust valves.

2. A recent cylinderhead rebuild [occasioned by a dropped valve seat] revealed these valves to be in pristine condition. [The original TC inlets were also fine although they have a gazillion more miles on them and may well be original Class of '69ers.]

3. NZ offers 95 octane ULP of sometimes uneven quality.

4. A squirt of upper cylinder lubricant [Morays - which is probably much the same as Redex] is added to the petrol after every refill. [Revs are kept to conservative levels plus the legal maximum road speed in NZ is a mere 60 mph.]

Then that's really good!

I wonder if the fact you had SC valves made some difference? (Remember I said TC heads and valves etc seem to suffer more from modern-day petrol)

 

[j_radcliffe]

That is interesting. I run Morey's as well, and have done since I had valve issues when Lead Replacement Petrol came in in Australia. I stopped using that fuel and just run 95 or 98 as that is all that is available now. I think that they tried to make LRP as bad as possible so people would not buy it and then the refineries could stop making it.

I figure that Morey's and Flashlube are both recommended for LPG usage, and since LPG is tough on the valves then the stuff should work well for running without lead in the fuel. I run Flashlube on my US based Rover. I cannot get Morey's there. I think I will keep doing what I have been doing. Both motors are running well. I think that the other way to keep your exhaust valves in good shape is to avoid overrun. When LRP came in I started to have overrun issues and then had 2 burnt valves not long after that. The other time I have overrun issues is in the summer time. To avoid this I keep the cooling system in good shape, and keep the idle speed no higher than I need it to be.

Perhaps we need to set up a head with 2 SC exhaust valves, 2 TC valves, run it for a while, and periodically examine with a boroscope. That way the valve condition can be monitored without pulling apart a motor that may be running well.

James.

 

[chrisyork]

Hi James

It's early in the morning here and I misread your post above as wishing to examine the valves using a horoscope

I fear that your suggestion would be no more use than that though - the sample size is not statistically significant and you would be unable to unscramble whther you were looking at chance, a valve causation, tappet clearance issues, unequal mixture distribution etc etc

I do think that you are concentrating too hard on the valve material in this thread and not giving sufficient prominance to all the other factors in the engine that could lead to valve damage. I'll list a few of them here. We can go on to discuss their likelihood and possible mitigation strategies, but I fear that the bottom line is that this engine is simply prone to valve failure. Provided that this is attended to promptly once symptoms are apparent, serious engine damage rarely occours as a result, so I think that that is the closest we are going to get without substantial re-engineering of significant chunks of the engine.

A few contributory causes:

# timing chain stretch and whip causing inaccurate valve events

# timing chain stretch and whip causing inaccurate ignition timing

# 2000TC in particular is over carburettored, so slow running mixture control is very difficult to set and maintain

# SC head has spectacularely poor inlet tract design - bound to lead to poor mixture distribution

# heron head combustion chamber design is poor by modern standards - potential for hot spots in the combustion chamber

# engine block is arguably over-lightened by side "window" design (evidenced by very poor main and big end bearing life), so engine flex may well disturb valve clearances at high rpm


Chris

 

[j_radcliffe]

Hi James

It's early in the morning here and I misread your post above as wishing to examine the valves using a horoscope

I fear that your suggestion would be no more use than that though - the sample size is not statistically significant and you would be unable to unscramble whther you were looking at chance, a valve causation, tappet clearance issues, unequal mixture distribution etc etc

I do think that you are concentrating too hard on the valve material in this thread and not giving sufficient prominance to all the other factors in the engine that could lead to valve damage. I'll list a few of them here. We can go on to discuss their likelihood and possible mitigation strategies, but I fear that the bottom line is that this engine is simply prone to valve failure. Provided that this is attended to promptly once symptoms are apparent, serious engine damage rarely occours as a result, so I think that that is the closest we are going to get without substantial re-engineering of significant chunks of the engine.

A few contributory causes:

# timing chain stretch and whip causing inaccurate valve events

# timing chain stretch and whip causing inaccurate ignition timing

# 2000TC in particular is over carburettored, so slow running mixture control is very difficult to set and maintain

# SC head has spectacularely poor inlet tract design - bound to lead to poor mixture distribution

# heron head combustion chamber design is poor by modern standards - potential for hot spots in the combustion chamber

# engine block is arguably over-lightened by side "window" design (evidenced by very poor main and big end bearing life), so engine flex may well disturb valve clearances at high rpm


Chris

Its funny that you mention sample size and statistics, and saw my old Biometry lecturer driving around yesterday in his 1972 red combi van, which he has probably had since new. Although his lectures were a general cure for insomnia I did still wave to him! Trev is not a bad bloke, and I like his style in cars. I agree you are making a valid point.

I will discuss with fellow Rover 2000 owners their experience exhaust valve at NatRove in Stanthorpe, Queensland, and report back if I hear anything that adds to this.

As for inspecting with horoscopes I should try to proof read a bit better especially when posting early in the morning after little sleep due to jet lag from just having flown from NY to Australia. Boroscopes on the other hand have come down in price enough that owning one would be an option these days and I will probably buy one of these days as a new option for diagnosis. A horoscope on the other hand could be used to predict when the Rover might have problems next!

James.