Unless your valve gear is extremely light weight, you
should probably be running at least 105 lbs of
pressure on the seat with the valve closed. A G3 cam
is a pretty aggressive grind that is designed to run
up close to 6800 rpm. 95 psi on the seat is not enough.
Greg Solow
The Engine Room
Sports Car Specialists
Santa Cruz, CA 95060
831 429-1800
------- Original Message -------
>From : timmmurphh--- via
Fot[mailto:fot at autox.team.net]
Sent : 2/15/2017 9:20:12 AM
To : fot at autox.team.net
Cc :
Subject : RE: Re: [Fot] valve spring pressure on TR4
race engine
Thanks for all of your responses. We are going to
add 0.030 shim to give 1.625 in spring height with
valve on seat for a spring pressure of 95 lbs. At
valve full open with .342 max cam lift and 1.5 rocker
arm ratio with a 0.016 valve clearance setting
(Kastner G3 cam) we should get about 244 lbs. of
spring pressure with the maximum valve lift of 0.497.
At least that is what I calculated. As a note, I did
get some valve float at about 6200 to 6300 RPM at
Elkhart Lake last Fall with the 85 Lbs. of seat
pressure when I went over our max RPM of 6000 trying
to get past a Volvo. Tim Murphy From:
timmmurphh at gmail.com [mailto:timmmurphh at gmail.com]
Sent: Tuesday, February 14, 2017 1:56 PM
To: fot at autox.team.net
Subject: valve spring pressure on TR4 race engine 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 Murphy1961 TR4 #317 BRG
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