Morris Minor Owners Club

Hi all,

When I fitted my recon 12G940, which came with double valve springs, I removed the inner spring and then fitted the head. It has suddenly occurred to me that this may have been a stupid idea...

Can anyone explain what is or what may be the consequences? Is it possible to remove the caps without removing the head? I guess not as I have to de-torque head to remove rockers.

Any advice/experience welcome.

Thanks,

Edd

I believe the outer 'half' of a set of double springs is less strong than a standard single spring. However, you won't be the first person who has done this. Presumably you didn't fit the double springs because you were worried about the additional wear on the rocker assembly? I know that quite 'strong' advice has been given on here in the past by a certain person against using double springs...

To be honest, if your car is running OK, I wouldn't worry. I would imagine that the most likely consequence would be valve bounce if you rev the engine hard enough (due to the weaker springs), but I doubt you've experienced that, as if you had, you would know about it!

It has suddenly occurred to me that this may have been a stupid idea...

Not 'may'; it 'was'. One might wonder why they supplied double valve springs in the first place?

I daresay one could replace them without removing the head. See a previous thread re removing valve springs, or fitting valve stem seals, or something else. Probably easier to do the job properly after removing the head, especially for an amateur.

These things happen.
There is absolutely no problem with having single springs on a 940 head.
The majority of 940 heads were only fitted with single springs.
The single 997cc Cooper valve spring Pt No: AEA311 (88lb @ 0.973") became the standardised single spring for 850 Minis and single carb 1100cc 'A' Series heads and allowed a rev limit of 6500rpm before valve bounce/crash.
The additional inner spring Pt No: AEA401 (30lb @ 0.0847") and used as a pair were used on the 998cc Cooper and twin carb 1100cc engines.
The single valve springs fitted to the 1300cc and 1300ccGT engines Pt No: 12G1015 (124lb @ 1.065") but have a greater free length of 1.953".
The inner spring of a double valve spring set was fitted to help damp valve bounce/crash at high revs and so enable the rev limit to be increased before valve bounce/crash occurred.
It is quite easy to fit springs of a poundage that exceeds that which is required and which will overload the valve train.
I consider that you can safely assume that the single outer spring fitted will allow engine revs to reach 6500rpm.
Therefore personally I would not rush to fit the additional inner valve spring but see how the engine runs - you can always fit the inner spring at a later date.
If you do fit the inner valve spring you must make sure that the inner spring bottom locators are in place (these stop spring float), the top caps are the right ones i.e. have a flat step to accommodate the top of the inner spring and the springs do not get coil bound when the engine is turned over.
Phil

Many thanks chaps!

You are correct that I had it imprinted in my head to not use double springs! It was only after reading another discussion I realised that double springs may not be the single spring plus an extra.

The engine runs fine, still running-in so only up to 3000rpm lately. I will keep an eye/ear on it and report back if necessary.

Edd

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