Valve Springs

[Malcolm Parker]

I am currently putting together a new engine that will initially go in the Pytchley but could end up in the single seater.    The bottom end has a splash fed Hadley crank and rods.  The cam is an unknown quantity but came from Reg Nice.  It is a very nice piece of machining and is a standard cam that has had 0.050" ground off the base circles.  The block is the one that was on my Reliant cranked pressure fed engine.   It has Honda pistons and large inlet valves.   The cam followers are flattened to 3/4" radius and the valve springs, as far as I know are from an Austin Maxi.  I remember the engine being done by Andy Hastings and Walt Wheaton back in the late 1990's and they said that Maxi valve springs were as good as double valve springs.  To my mind the valve springs are very strong and I am wondering whether they will be suitable given that I am now using a high lift camshaft.   I am thinking about the effect on the block holding down studs and the valve heads.   Would I be better using standard valve springs?

[Charles P]

I've used Maxi in the past and yes, they're very strong. I wouldn't now.
The ambition should be to use the weakest springs that will do the job.
A few years ago I tested a bunch of springs for load across the lobe and base and came to the conclusion for my high lift cam doubles from Tony Betts gave the right loading for my use. They were actually no stronger than standard springs, but being wound from thinner wire didn't coil bind at full lift and should avoid unpleasant harmonics.
No problems to date

[Alan]

Back in the 70s and 80s I think we used Maxi valve springs because the then available Austin springs weren’t up to the job. I never use double springs now unless I’m building a race engine. Standard springs from any of our suppliers are good for up to 5000 revs or so, and the doubles I’ve been using see 8000 occasionally without noticeable valve bounce. Malcolm a .050 base circle regrind makes quite a nice cam. I used one for years until one day the crank broke and bent it.

[Ruairidh Dunford]

In the last 10 years I've had 3 engines come in with the rear foot missing off the back of the block.

All of them had these Maxi valve springs and a high lift camshaft fitted.

[Malcolm Parker]

Thank you all, I'm glad I raised the question!  My gut instinct told me that the springs seemed mighty stiff, I could hardly press the cam follower down against the spring pressure.   I will fit some standard springs.

If I see 8000rpm in the Pytchley it will probably be my final post!

[Reckless Rat]

Being tighter than a submarine's window I admit to having suffered cringes when you first outlaid your plans,
Malcolm. Personally ( and I know it's none of my business) I would remove the Hadley crank and mount it on a nice piece of olive wood and keep it on display in the living room. Replace it with a phoenix or even a known Austin crank until the day of reckoning, as described by our bearded wizard eventually arrives. Please don't Let us say " I knew that would happen".

But, if it's on your bucket list, just do it... fingers crossed.

[Malcolm Parker]

The engine in the Pytchley was the first engine I built back in 1982.   It has been in various cars (all specials) ever since and has seen some service.   It has an original crank.  Thinking back, it was a bit dodgy as the rear journal had been repaired by chromium plating following wear caused by the rear main spinning.   43 years on, it still goes like a bomb but it is becoming increasingly incontinent to the point where it is embarrassing.  This sounds very bad but is true, in 43 years I have never had the sump off.   
The Hadley crank and rods, together with the white metalling, are quite an investment.    I suppose I could have had a life where the money went on booze, gambling and women!
My wife wouldn't approve of a crank on display on the mantlepiece.    A horse or sheep, yes.

---

Back on thread the Maxi springs have been removed and I have fitted a set of old double valve springs that I had in stock.   They don't feel much different to the Maxi springs but I am happy to be using proper Austin 7 parts.     Changing the springs was a good chance to clean up the valves, all of which are in excellent condition.   Managed to replace all the fiddly collets without too much cursing.

[Tony Griffiths]

The engine in the Pytchley was the first engine I built back in 1982.   It has been in various cars (all specials) ever since and has seen some service.   It has an original crank.  Thinking back, it was a bit dodgy as the rear journal had been repaired by chromium plating following wear caused by the rear main spinning.   43 years on, it still goes like a bomb but it is becoming increasingly incontinent to the point where it is embarrassing.  This sounds very bad but is true, in 43 years I have never had the sump off.   
The Hadley crank and rods, together with the white metalling, are quite an investment.    I suppose I could have had a life where the money went on booze, gambling and women!
My wife wouldn't approve of a crank on display on the mantlepiece.    A horse or sheep, yes.

---

Back on thread the Maxi springs have been removed and I have fitted a set of old double valve springs that I had in stock.   They don't feel much different to the Maxi springs but I am happy to be using proper Austin 7 parts.     Changing the springs was a good chance to clean up the valves, all of which are in excellent condition.   Managed to replace all the fiddly collets without too much cursing.

As the ex-Manchester United and Northern Ireland footballer George Best once quipped: "I spent a lot of money on booze, birds and fast cars. The rest I just squandered."