REPLACE VALVE SPRINGS OR NOT??

lrjohn · Jul 8, 2025

I would appreciate your thoughts – I am rebuilding the cylinder heads on a 3.5 v8, carb version, from a Discovery 1 which has 75,000 miles on the clock which I believe to be genuine. I am going to re-grind the valves which all look good and no play in the valve guides. Question - is it necessary to replace the valve springs? Springs themselves look fine and tappets are good with minimal wear, very minor rub marks where they have sat on the cams.

Whilst asking, the official Land Rover workshop manual says nothing about replacing the head bolts so I assume they are ok to reuse?

All comments are much appreciated!

biketeacherdave · Jul 8, 2025

Springs should be fine, replace the bolts with new.

marjon · Jul 8, 2025

Sure the springs can be measured, specs in the manual?
But at that mileage I wouldn’t expect them to be an issue.

J

lrjohn · Jul 8, 2025

Th

biketeacherdave said:
Springs should be fine, replace the bolts with new.

Thanks for the advice!

Henry_b · Jul 8, 2025

no need.

Head bolts should be re placed.

lrjohn · Jul 9, 2025

marjon said:
Sure the springs can be measured, specs in the manual?
But at that mileage I wouldn’t expect them to be an issue.

J

Thanks for your advice, measuring the springs makes sense – I will find the specification

Stanleysteamer · Jul 9, 2025

At that mileage springs will not be a problem, the known weak point of these engines is the camshaft, so you might want to check that out and the oil supply to it.
When you measure the springs they will be bound to be slightly compressed compared to new but unless you are getting valve bounce I really wouldn't bother with changing them.
Do make sure the valve seals are changed though, if there are any on that engine. (Although I have one I have never had to do any work on it yet!)

lrjohn · Jul 9, 2025

Stanleysteamer said:
At that mileage springs will not be a problem, the known weak point of these engines is the camshaft, so you might want to check that out and the oil supply to it.
When you measure the springs they will be bound to be slightly compressed compared to new but unless you are getting valve bounce I really wouldn't bother with changing them.
Do make sure the valve seals are changed though, if there are any on that engine. (Although I have one I have never had to do any work on it yet!)

Thank you, much appreciated. I did find the spec for the valve dimensions, 1.9 inches unloaded, and they are all at that length so that is excellent. Good recommendation on the camshaft, I will take a look. I did buy valve stem oil seals, only required on the inlet valves. They are slightly odd in that they are simply a rubber washer in effect so will be floating as opposed to a seal that fits like a cap over the valve guide, the old ones were rock hard and cant have been very effective

REPLACE VALVE SPRINGS OR NOT??

lrjohn

Active Member

biketeacherdave

Well-Known Member

marjon

Well-Known Member

lrjohn

Active Member

Henry_b

Think outside, no box required.

lrjohn

Active Member

Stanleysteamer

Well-Known Member

lrjohn

Active Member

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