Paul,
Peter Burgess, in "How to Power Tune MGB Engines", says that the
single springs in the 18V engine are suitable for cams of up to 400 thou
lift and allow 6200 rpm before valve float. Double springs allow 430
thou lift and 6400 rpm. The standard camshaft and several of the mild
aftermarket camshafts lift about 350 thou. For street use, the 6200 rpm
limit is not a problem.
There is some power consumed in compressing valve springs and they put
pressure on the camshaft, which is an argument for the softest springs
that will shut the valves adequately.
There must be 150,000 or more 18V engines running with single springs,
so they work OK, but as your head may not be one of the heads originally
fitted to 18V engine, the head could have had double springs from new.
Barney Gaylord's site has a page showing various heads used on the MGB
engines and the marks to identify them. I don't see why a single spring
would not work on any of the heads, but you would want to check Barney's
chart and have the machine shop check over the head and the springs.
Bob
On Thu, 3 May 2007 07:39:35 -0400 Paul Osborne <paul@ece.rochester.edu>
writes:
> Hello, Looking for input on the advantages/better choice of single
> or double valve springs on a 18v head.
> I am rebuilding a head and it has double valve springs , but I have
> a new set of singles from and other project that I did not use. I see
> know reasons that I should not use them. Comments please . thanks
>
> paul
> --
> Paul Osborne
> University of Rochester
> Engineering & Technical Services
> Department of Electrical and Computer Engineering
> 201 Hopeman Bldg River Campus
> Rochester, New York 14627
> 585-275-5226
> paul@ece.rochester.edu
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