Lead replacement or redo valve seats?

[shed driver]

Soon, I'll be buying my first classic. It will be dating from the days of leaded fuel and five star petrol.

In an unrestored car, should I be using a lead replacement additive, having the valve seats redone, or just leave it alone?
The car is likely to be a Rover P5B - but I've got a few months to change my mind!

SD.

[john2443]

Probably best to use an additive, although at the time leaded was discontinued there was debate in classic mags that on low mileage the valve seats would last years without it and if the seats erode you can have them replaced with hardened ones in a few years instead of doing them now.

If you need to take the head off it's worth having them done at the same time but I wouldn't take it apart just for that.

[sparkythecat]

A Rover P5B has the V8 engine doesn't it?
As long as you don't thrash it at high revs, it won't take much harm on unleaded.
Another alternative is to fit heads from a later engine.

[Allan L]

Since the Rover V8 has aluminium alloy cylinder heads, the valve seat inserts are likely to be made of suitably robust material so that VSR would not occur. I'd also suggest that the prolonged use at high power and high RPM necessary to fall foul of VSR is pretty unlikely so don't spend money on fixing it!

[grumpy52]

Most people worry about the lack of lead in modern fuel and get all panicky about valve seats , it rarely causes a problem unless the vehicle is constantly driven at motorway speeds over longer periods.
What most ignore is many of the older cars were set up to run on higher octane fuel and not the 95 ron that is the most common in the UK .

[Old Merc]

Allan L said:

Since the Rover V8 has aluminium alloy cylinder heads, the valve seat inserts are likely to be made of suitably robust material so that VSR would not occur. I'd also suggest that the prolonged use at high power and high RPM necessary to fall foul of VSR is pretty unlikely so don't spend money on fixing it!

I agree, a few years ago I helped restore an early 60`s Peugeot. It had an alloy head with hard inserts. It must have done tens of thousands on modern unleaded fuel, the valves and the seats were like new.
I bet though it would have been different with a BMC A or B engine. I can remember my apprenticeship days, when fuel was all leaded, a decoke, new valves and seats was a regular job.

[lowdrag]

When California introduced lead-free petrol in - from memory, 1964 - Jaguar made no alterations to their XK engine. The cylinder head is alloy but had hardened valve seats. No problems were reported. I have been using 95 RON petrol with 5% ethanol in the E-type for many years and when the engine was rebuilt a few years back there was no erosion to the seats. However, with 10% in view I shall be buying this for added protection:-

https://www.duckhams.com/product/classic-fuel-trea...

[Riley Blue]

Old Merc said:

Allan L said:

Since the Rover V8 has aluminium alloy cylinder heads, the valve seat inserts are likely to be made of suitably robust material so that VSR would not occur. I'd also suggest that the prolonged use at high power and high RPM necessary to fall foul of VSR is pretty unlikely so don't spend money on fixing it!

I agree, a few years ago I helped restore an early 60`s Peugeot. It had an alloy head with hard inserts. It must have done tens of thousands on modern unleaded fuel, the valves and the seats were like new.
I bet though it would have been different with a BMC A or B engine. I can remember my apprenticeship days, when fuel was all leaded, a decoke, new valves and seats was a regular job.

It was only after the head gasket failed in my Riley One-Point-Five's B Series 65,000 mile engine a few years back that I considered hardened valve seats. Had there been no HGF I wouldn't have bothered. On examination, there wasn't a great deal of VSR though as the head was having some work done, hardened valve seats were fitted.

I think the risk was overstated in years past to sell unnecessary additives.