Valve recession - How much of a problem for the 1500 engine

[Richard the old one]

We have all read about valve recession but in real life I am interested to find out how many people have actually suffered from this problem in their engine.

If you have, what sort of use has you car had and what mileage was covered using lead free petrol.

[Carledo]

I did over 40,000 miles in my mkII GT6 (which took it to 130k) Yes it's a 6 pot, but the head design is almost identical to that of the 1500. All the mileage I did (including several trackdays as well as everyday thrashing) was on ordinary unleaded fuel and the engine was original and unmodified. I did not even bother with octane booster or lead replacement additives. I did not deliberately set out to test what would happen, I just decided that when it failed, I would get the head converted - it never did! When the body got bad again after 5 years as a daily, during which time it got left in a snowbank twice, I broke the car and sold off most of the bits including the engine and as far as I know, it's still running now! As far as I am concerned, lead memory is a reality!
Back in the 80s, when leaded fuel started disappearing from forecourts, Practical Classics did a field test on an Austin 1800 which only managed a couple of thousand miles before valve seat recession killed it. the only snag with this was, that they decoked the engine and ground the valves in to make sure the engine was in good order for the test and thereby destroyed it themselves by grinding away the lead memory!

I'm waiting to see what happens with "project satin black", Ken's old Toledo. Ken rebuilt the head but didn't convert for unleaded and then sold it to me. It's too soon to say yet though, as its only done about 200 miles under its own power since I bought it!

Steve

[Richard the old one]

Many thanks Carledo for your response. I have been adding reddex lead replacement to my cars just as insurance measure but I think based on your experience I will just add some when I am going on a motorway run. When on the motorway I generally like to travel at between 60 and 65 so with overdrive the engine is only turning over at just over 3000 revs.

My daily use dolomite has now just clocked up 300,000 miles. I did rebuild the engine at about 120,000 and it could do with some TLC again as it does burn some oil but it is still running fine and I have no problems getting it through the MoT in respect to emissions.

I was disappointed that you were the only person to respond.

[Triumph1300]

KAC, 1300 FWD has done around 60 k miles without unleaded, no additives, timing backed off a fraction to stop pinking, no problems yet, including track days, towing, and lots of abuse, including "cruising" at sustained 5000 rpm

[MIG Wielder]

Can't speak for the Triumph head but I decoked the cast head on the MGB 10 years ago and that was about 50,000 miles ago. It used to get a tankful of high octane leaded fuel from Castle Coombe / Cornwall / Wargrave / Yorkshire every 3 months in those days, depending where we were, but nothing in the last 7-8 years. No additives and I've usually used high octane Shell or B.P. fuel . No sign of valve recession. Remind me of this post in 5 years time.
Tony.

[Jon Tilson]

I have the same basic engine in a Spit 1500 that Ive had for well over 30 years...
head never off at 130k miles - still goes pretty well and no excessive oil use.

Just use Esso Shell or BP 95 unleaded

Jonners

[tinweevil]

These were taken 06 Oct 2007 (yikes) when the head was off to replace exhaust no 3. That's the replacement at the top and is quite badly recesssed, below is exhaust no 1 which as you can see is tunnelling it's out of the engine.

The head went back on and covered another 6000 miles until the engine came out at the end of Jan, I'd sourced an O/D box from Tony in Blackpool. That came with an engine and due to the above plus pretty poor oil consumption the 'new' one went in. Still, in those 6000 miles it returned 35.36mpg on the Horley <-> Bracknell commute.

That head had done 29k in 22 months for me. When it went on it was of unknown age, had sat loose for who knows how long and got zero love & care before it went on beyond the basic level of decoke you can see I've repeated in the above.

IME no1 is always the worst, the replacement head always needed more adjustment same as this one did. Biggest surprise for me in this respect was that when I fitted Britpart ignition the valve recession reduced hugely. Before I was backing the adjusters appreciably every 3000 miles, after I was leaving it longer, probably 6000, and backing off much less each time.

95 unleaded and no additives.