Symptoms of worn valve seats/usage of lead replacement

[Quack]

I imagine this topic has probably been covered many times but i couldn't for the life of me find any direct answers on the forum.

I currently use Redex lead replacement with every tank, however i see again and again online that it's just not worth the cost.

I'd like to find out how worn my valve seats are already to decide if its worth me continuing to use lead replacement or not, so I was wondering what the symptoms are. I saw that excessive oil consumption is one, which i certainly do have, so wanted to investigate a bit further.

I do drive on the motorway a bit, i'd say i maybe do about 3 to 4 hours of 55-60mph driving twice a month, if that makes a difference to my choice.

[Josef]

Checking if the valve lash is closing up is the direct measure. Without taking the head off that is! Valve seat recession is when the valves wear into the seats on the head. So if that happens then the top of the valve will get closer to the rocker arm. If you check your valve clearances periodically you’ll see if they are getting tighter, if they are then you may well have VSR. 

[johny]

The theory is that without lead protection of the valve seats they can get damaged over time and the two possible symptoms are loss of sealing (tested with a compression tester) and continually decreasing tappet clearance (requires regular readjustment of tappet settings). I cant see how oil consumption can be affected.

Unfortunately the problem seems to be quite erratic with some engines never suffering it while a few others do. Driving style and lead memory (where the use of leaded fuel years ago has left protection on the valve seats) probably have an effect but really you cant say beforehand if its going to happen or not. The definitive solution of course is to have hardened valves seats installed but this is an expensive job so most people say only do it if youre taking the cylinder head off anyway to repair a known issue....

 

[johny]

For long high speed runs I use Millers VSP which is lead substitute and octane booster which means I can use the cheapest petrol rather than Super (so recovering most of the cost) without having to retard the timing and still have the potential benefit of valve seat protection (Im pretty certain my MK1 Vitesse has previously suffered some damage)...

 

[NonMember]

I've driven many miles in Triumphs, mostly without any head work done, and without additives. I have encountered VSR precisely once - when the Toledo had been mercilessly thrashed Round Britain in 48 hours, three up, with a dodgy float valve that meant it spent most of that running severely lean. The tappet clearances had closed up to the point that there was no compression once cold.

As johny says, oil consumption is NOT a result of unleaded petrol use.

For your use, I'd forget about doing any head work and I wouldn't bother with additives.

[Quack]

That’s good enough for me, thanks 😂

[johny]

Do see if you get any pinking with the standard ignition timing though. With the car fully up to temperature and driving a flat road you should be able to floor the accelerator in 4th gear and any pinking (a rattling tinkling sound from the engine) should stop by the time you reach 2000rpm. If not you can back off the timing (=some loss of power) or use a higher octane fuel/octane booster additive👍

[Pete Lewis]

just filled up at sainsbury's  and 95 E10  is only a few pennies cheaper that 97E5

in the total cost of  a good few litres the improved performance and MPG of the E5 is no contest 

there is not a wild difference in cost but a good difference in bang for you bucks 

dump the cost of addatives use E5 and drive it till a valve problem starts to exhibit

in all the years of tssc triumph forums there has never been a posting of VSR as far as i recall

and generally  you only have hardened seats on the exhaust valves 

lead memory has proven to last for years 

Pete

 

[Quack]

I always use e5 premium but was also using lead additive. I drove about 4 hours over the weekend with no lead additive and all seems well so think I will ditch it

[Pete Lewis]

yes just use on high days and holidays  might use it up 

Pete

[Chris A]

I treat my 13/60 to an additive as often as I have a glass of whisk(e)y. Maybe that's why the car uses so much 🙄

Seriously though, I do use additive as I suspect the car has had valve work but not inserts so prefer to play safe.

[daverclasper]

5 hours ago, johny said:

(Im pretty certain my MK1 Vitesse has previously suffered some damage)...

Some seat recession?, Was it permanent damage, as such?. just out of interest

[johny]

I believe what happened was the wear of my carb spindles allowed air in, particularly at higher revs, so it ran weak on some long high speed runs. When I next came to check the tappet clearances some were very small and had changed much more than normal. Fortunately I was still able to set them to the correct gaps and have since changed the spindles so I dont expect further problems but the valve seats must have recessed substantially☹️  

[daverclasper]

Ahh. Maybe this could relate to the post in the" fuel" section about running weaker at higher  rpm, in some circumstances?.

[johny]

Definitely but also the Mk 1 six cylinder does seem to have more of a reputation for VSR...

[Pete Lewis]

spindle wear will allow fake mixture settings at idle and this will be on the rich side to mask the ingress of air so 

really wont affect mixture with the throttles opened ,and if set a tad rich at idle will be rich over the whole range  its   unlikely to go weak 

 

 my carefully modify 1600 was quite a flier and driven hard (not raced) for 15 years never missed a beat 

and never any valve problems and no  addatives  just E5

 

[Badwolf]

On the subject of lead memory. My engine was balanced and other stuff in the mid 80s and the valves ground in. Now the 'piece of string' question. Very roughly, how many miles on leaded petrol would I have had to do to obtain lead memory? I suppose the same could be asked if using lead replacement additive. I got a bottle of Castrol valve additive stuff ages ago before I learned about all this and treat the petrol every forth or so fill up just to use it up but generally use E5. The engine did about 25k before leaded went off the market.

[Pete Lewis]

the trouble with memory is .....Ive forgotten 

Pete

[NonMember]

2 hours ago, Badwolf said:

The engine did about 25k before leaded went off the market.

Probably more than enough. I doubt anyone's actually done the testing to get definitive figures but I'd expect it to be only a few k

[Nick Jones]

I belong to the "do nothing until a problem emerges" school of thought on this.  

On engines that have done plenty of miles on leaded and not been touched since (minimal or no valve seat grinding and certainly no re-cutting), you will get 10s of thousands of miles before recession sets in - if it ever does.  And then only if you do high speed mileages.  My original Vitesse engine did at least 25k fairly hard miles on unleaded (on top of an unknown but large mileage on leaded fuel) and never showed any sign of recession.  Head was changed for other reasons in the end.

However, if you do have to do work on the valve seats, especially the exhaust ones, you will remove some, or all of the lead memory and it's a good time to get inserts fitted.  A few years ago, we did a minimum budget engine build for my sons 1300 Mk IV based on an FD engine.  The head was medium rough and the exhaust valve seats were pretty pitted.  As he wasn't planning on keeping the engine very long I just tidied up the ports and ground the valves in best I could.  They really should have been re-cut as a minimum.

Fast forward about 3 years and the car has done around 10k miles - not very much of the that being high speed, open road mileage.  But life changes and suddenly it's commuter transport being driven hard on fast A roads every day and pretty soon it's taken ill.  #1 & #4 exhaust valves have no clearance left at all and 2 & 3 are tight.  Reset clearances and all is well again - for a whole 200 miles, when the problem recurs.  Rinse and repeat...... several times.  The car is needed every day  and there's no budget for head work.  Additive to the rescue.  Recession stops...... unless you forget the additive!  Something similar happened with my GT6 except I haven't got to the recession stage yet - only about 2.5k miles.  I do put additive in that if I'm going on a long fast run.  Otherwise I don't bother.

The cure is the same as the prevention in the end anyway.

Nick