[Fot] valve spring pressure on TR4 race engine

Wed Feb 15 13:31:41 MST 2017

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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