Lotus Europa Forums > The Paddock

Cross-Flow (TS) valve-train life with performance cam?

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GavinT:
I suspect 6mm stems may be difficult to find in large head diameters. These small valve stems were a characteristic of more recently developed four valve heads which inherently use smaller valves - just multiples of them.

Richard48Y:
Cross-posting here for those who may not follow the regular "Garage" threads.

Gave up on the Beehive springs, they are possible but difficult and not as much gain as hoped.

Got my tricky Ford 7mm stem valves, guides, and Ford springs from Salv Sacco today.
Going to be a bit of work to install them but I am sure they will be worth it.

Nor certain how spring weight figures into valve-train calculations, but these weigh 48 g instead of 91 g.
Even if only half the weight is calculated as mass the savings are still significant.
Spring retainers in steel 14 g vs 32 g.
Aluminum would be 6 g, Titanium are 9.07 g and about $175.00.
7mm Intake 68 g vs 80 g.
7mm Exhaust 57 g vs 78 g

So I save at least 30 g - 39 g per valve not including the springs.
The Mini site claims each 10 g savings is good for an additional 350-400 RPM of revs.
I know my RPM is dictated by how long I want my crank to live, so no increase in RPM but hopefully significantly longer cam and valve-train life.

Head will be taken to HBR in Las Vegas at the end of this month for the valve work and very light porting.

GavinT:
Valves look neat - were you able to find 42mm inlets?
Weight savings on reciprocating gubbins is invariably welcome, I reckon.

Richard48Y:
Yes, Salv fixed me up.
"In for a penny, in for a pound", so I will probably bite the bullet and get Ti. retainers too.
Another 5 g off each valve.  8)
Depending on who you ask valve spring weight is figured as half or one-third.
So another 20 g taken off.

Certainly all overkill for a street engine and I know it will not raise my crank-life ordained redline.
But do believe I will get a fraction more flow and less strain on the valve-train.
Lighter should open and close with less inertia, that has to be a good thing.

Now to figure out how to remove the tubes around the spark plugs?

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