[Fot] valve spring pressure on TR4 race engine

[Larry Young]

Those are pretty close to the stock springs. Most likely your engine guy 
is used to big American V8's with heavy valve trains.

I got very interested in cams and valve train dynamics when I started 
racing 15 years ago. I tried to figure this stuff out using engineering 
principals (always a dangerous idea). I read all the books and a ton of 
SAE technical articles and have also done calculations with valve train 
dynamic models. When the lash is first taken up at speed, it causes an 
impact event, akin to smacking a tuning fork with a hammer. I don't 
believe this situation is accurately modeled. So, the seat pressure is 
basically determined experimentally. The ramp design and valve lash have 
to be very important because it determines how hard you smack the tuning 
fork and can effect things like valves bouncing off the seat at closing. 
All too often I have found that cams from the usual suspects seem to 
disregard the idea of ramp design - see the bottom of 
http://tildentechnologies.com/Cams/Tip_Lash.html.

  - Larry

On 2/14/2017 1:55 PM, timmmurphh--- via Fot wrote:
>
> I have 85 lbs. pressure on the intake valve with the valve closed and 
> it sits at a height of 1.655 inches.  At .400 lift, I have 190 lbs. of 
> pressure.  We only run to 6000 RPM with the gearing we have and the 
> engine we have.  The valve springs are double springs and the machine 
> shop says they are all about the same, very consistent.  What 
> pressures would be recommended?  The machine shop thinks these 
> pressures are light for a 6000 RPM engine.  Any advice will be 
> appreciated.  Thanks.
>
> Tim Murphy
>
> 1961 TR4  #317 BRG
>
>
>
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