I agree with Brian's figures. He has been reliably racing his TR powered Morgan
for years. David Newman (Newman Cams England) was saying 110 on the seat and I
think 225 at full lift was sufficient (I'll look at my notes this weekend re
other cams and pressure at full lift).We saw a lot of engines with way too much
valve spring pressures causing wear and robbing horse power.Weight of valve
train components, valve size, collet retainer material, ect all play a factor
and checking for coil bind is critical. Sealed Power make a range of valve
spring shims thicknesses that will increase you spring pressure, I have part
numbers and thicknesses but am unable to get back home right now with mudslides
and road closures here in Santa Cruz. Greg Solow (Santa Cruz CA) and Dema Elgin
(Santa Rosa CA) have years of experience with various cams and valve spring set
ups for TR3/4 engines.Pat MannionSanta Cruz CA
---------- Original Message ----------
From: davehogye via Fot <fot at autox.team.net>
To: Jason Ostrowski <jason at multivintage.com>
Cc: Friends of Triumph <fot at autox.team.net>
Subject: Re: [Fot] valve spring pressure on TR4 race engine
Date: Wed, 15 Feb 2017 05:05:46 +0000 (UTC)
Yes! Let's hear some wisdom on this subject from Santa Cruz. Greg, please
guide us with your knowledge.
DH From: "Jason Ostrowski via Fot" <fot at autox.team.net>
To: "Peter Vucinic" <pvucinic at netspace.net.au>
Cc: "FOT" <fot at autox.team.net>
Sent: Tuesday, February 14, 2017 7:52:41 PM
Subject: Re: [Fot] valve spring pressure on TR4 race engine
This post has been swirling around in my head all day... Since We have always
run 65 lbs closed pressure for the GT6 motors with several different cam lift
scenarios... My initial thought and answer for Tim's inquiry would have been
that 85 lbs seems just fine. I almost posted 85lbs seems just fine as if I
really know what I'm talking about. And as I thought about it; the variables of
stroke, size, height, wet liners, etc. may have all types of influence on the
settings. With all that in mind I figured that I didn't have any reason assume
that what we do with the GT6 would be at all applicable to the original
inquiry. But I really wondered why his machinist would think that 85lbs is
"light". Then the trusted voice of my mad German speed demon pipes in and says
that it should be higher by an off the chart amount of poundage!Since he runs
so well with a certain amount of reliability and obvious speed; it remains of
interest to me (with now less understanding than prior to the original post)
to fundamentally backtrack the inquiry of spring pressure theory. It seems that
a huge # would yield a stronger bounce that would have certain benefits. It
also seems that a stronger bounce would meet certain limits of stress on
components and result in dangerous scenarios. Thus, there must be a line to
cross, a minimum and a maximum. Dear Confucius, what say ye to the boundaries
of such...and please, oh great one, present the essential expose. The formulaic
dynamic as to the characteristic makeup of proper spring pressures is???I
always look to the west for such guidance, perhaps some wisdom exists in Santa
Cruz?Jason OstrowskiFriendly Ghost Racing1969 Triumph GT6+ Racecars
Sent from my iPhone
On Feb 14, 2017, at 7:32 PM, Peter Vucinic via Fot <fot at autox.team.net>
wrote:
I would be EXTREMELY careful with too high a spring pressure. Been there, done
that! If you go by all the STD calculations, theories and what you
‘should have’ texts. It will tell you need HIGH springs pressures.
Destroyed a couple of cams that way! I just went back to springs with about the
seat pressures you are looking at. Haven’t had an issue with cams/cam
lobes since.
"You can Make a Small Fortune From Motor Racing. As long as You Started With A
Lage Fortune!"
Kind Regards
Peter Vucinic
TR4 - TR7 V8 - Spitfire MkII
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From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of timmmurphh--- via
Fot
Sent: Wednesday, 15 February 2017 6:56 AM
To: fot at autox.team.net
Subject: [Fot] 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 Murphy
1961 TR4 #317 BRG
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