Twin Valve Springs

[Lowbarn]

Is it normal to have two valve springs on each valve?


   

[Nick Lettington]

Only if you want to rev the nuts off it...

Unlikely to be used in isolation... where did the engine come from? It may have other go faster mods.

[Lowbarn]

Don't know much about the cars history. Previous owner did a lot of work but nothing on the engine. I don’t think he had much luck tracing the owner previous to him either.

Pistons are marked 04 so presume it’s been rebored. 

Home would I find out if the cam is hot?

[Adrian Payne]

Judging from the one cam lobe we can see in your other post, I would guess a standard cam. Flanks are straight and the radius is fairly large.
There is an article on cams here. https://www.austinsevenfriends.co.uk/Bru...files.html
Adrian.

[Lowbarn]

Thanks for that Adrian, I’ll measure up in the morning.
Have you seen an imperial dial vernier?
Not sure if that would be easier than converting everything to metric.
Richard

[Bob Culver]

Need only be sufficently strong to place bounce revs somewhat above used revs. On standard geared standard non sports models over 40 mph in 3rd (or 2nd)....... Stroger springs just add friction and wear.
For decades I ran a Jowett Javelin. These wear non replaceable cam bearings which with a flat enine is significant. Also wear valve seats, partly due the cam wear. I eventuaully ran mine with inner spring removed. Valve bounce was 65 mph but it was driven great distances at 60. Seat wear reduced.

[Lowbarn]

Checked the camshaft it is a standard cam. The head is low compression updraft.

[Tony Griffiths]

The only advantage of double valve springs on a standard engine is if one should break (most unlikely in normal) use the other will get you home. Otherwise, they just put greater stress on the valve train.

[Lowbarn]

Sounds like I would be advised to return the valve train to standard specification.
I’m not interested in performance from this Austin, more about reliability.

Plan is to put the engine back together with the revised bush restraint then see if the knocks gone.
Then consider engine rebuild when the performance / oil usage gets excessive.

I’m learning a lot about these engines in the process. So far I’m impressed with the simplicity and ease of access. I’ll be really impressed if I get it going again!!

[Alan]

The inner spring adds little in the way of loading. It’s really there to damp the outer spring to prevent valve bounce. Unless you have a particularly high lift cam or a desire to rev above 5000 you can leave then out.