Section : Oil and Filters

Oil cooler and auxiliary oil feed on a 1500 Spitfire

Posted By : James Lavery, 13-Feb-2003, 09:43pm

Having now finished overhauling the front and rear suspention, brakes and anything else that moves I am moving on to the engine and am thinking about fitting an oil cooler, extra feed pipe for the rocker shaft. Anyone got any opinions on either of these. Also I have been told that Ford valve stem seals can be fitted as anyone heard of this or am I being wound up.

Followups :

Oil cooler and auxiliary oil feed on a 1500 Spitfire

Posted By : Don Cook, 14-Feb-2003, 12:16pm

James

I'm interested in fitting valve guide seals to my GT6 so I've started a message thread on that board - keep a look out as I'm hoping for some expert advice. Incidentally expect higher oil consumption (unless you're fitting new guides and those seals!) if you fit the oil pipe to the rockers!
- Auxiliary oil feed
  
  Posted By : John Davies, 14-Feb-2003, 09:21pm
  
  James,
  
  In my view the reason for fitting the auxiliary oil feed to the cylinder head is because you can! The rocker bearings are under no strain for most of the cycle, when oil can easily feed from the rocker shaft, then BLIP! they do a quick nod and back again.
  
  The downside is that the new oil feed usually comes off the main oil gallery via the oil pressure sensor port, well before the feeds to the main bearings. The rocker shaft feed is relatively low resistance, so much oil goes that way, potentially starving the mains. I believe that this has happened to me, or rather to my engine in the past.
  
  It may be better if the rockers and shaft are brand new, but a discussion on http://www.triumphspitfire.com concluded that an orifice, a narrowing in the aux. oil feed, was needed to stop the mains being starved. No advice however on what size of of orifice, or where to get one.
  
  I would only use one if I was building an engine for really high revs, with high ratio roller rockers or stiffer valve springs, when a new rocker shaft would be essential anyway.
  
  Now, any other views?
  John
  - Auxiliary oil feed
    
    Posted By : Laurence Cochrane, 14-Feb-2003, 10:27pm
    
    John
    
    Have I you worried ?
    
    Only inputing to say I would agree.
    
    However your querie about an orifice and where to get one,
    We have an orifice in work, thats where the orifice workers sit.
    
    I think they meant restrictor.
    
    Laurence
    - Auxiliary oil feed
      
      Posted By : John Davies, 15-Feb-2003, 00:46am
      
      No worries, Laurence, just humility!
      
      And orifice, schmorifice, it works like a restrictor.
      
      In fact an orifice is wider than its' length, like the hole in a washer, while a restrictor is the opposite, like a length of pipe. You're right, an orifice works better in turbulence, when density determines flow. In a pipe, laminar flow varies as the fourth power of the narrowest diameter, so a restrictor a quarter as wide will reduce the flow to a sixteenth of what it was at the same pressure drop, ignoring length. But the conditions with an external oil feed are very different in bore, length and upstream pressure, so that calculation cannot easily determine the required internal diameter of the restrictor.
      Achieving a better oil supply for the rockers, without robbing the mains, would need careful measurement of flow before and afterwards. Possible, but tedious, and I am far from convinced that it is needed at all.
      The blanking bolt in the back of the head is there, not to allow this modification, but to blank off the horizontal drilling that connects the two vertical oilway drillings between camshaft and rocker shaft. Just like the socket headed bolts in the block that blank off the surface holes of the drillings from the main oilway to the main bearings.
      John
      - Auxiliary oil feed
        
        Posted By : Nigel Gibbins, 16-Feb-2003, 02:23am
        
        My solution (or my engine builders) was to drill out all the oil ways in the block. With these enlarged paths much more oil is flowed around the engine as a whole and ergo - the head. I have not yet had any problems, and I rev to 8,000.
        
        I have also been advised if you ARE going to fit a rocker feed pipe you should take the oil from the rear most Screw plug on the oil galley - Not from the pressure relief valve.
        
        Any theories on that fellas?
        NiG
      - Auxiliary oil feed
        
        Posted By : Laurence Cochrane, 16-Feb-2003, 06:28pm
        
        I tried to cut you some slack in the hope that you would start to think before comiting to print.
        But Oh no! you open your mouth then put your foot in it metaphoricly speaking.
        Or I should say "put a restrictor into an orifice.
        An orifice is a opening in a surface irespective of the relationship between it's diameter and depth.
        
        An opening, especially to a cavity or passage of the body; a mouth or vent.
        [Middle English, from Old French, from Late Latin rificium : Latin s, r-, mouth; see s- in Indo-European Roots + Latin -ficium, a making, doing (from facere, to make. See dh- in Indo-European Roots).]
        
        A restrictor is any DELIBERATE ( As oposed to a restriction which can be unintentional ) obstruction in the pathway of normally a fluid, with the intention of reducing flow rate increasing / decreasing pressure. or in the case of a venturi increasing velocity. Obviously dependant on perspective.
        
        To keep or confine within limits.
        [Latin restringere, restrict- : re-, re- + stringere, to draw tight; see streig- in Indo-European Roots.]
        
        Please try to keep your errors to a minimum the intention is to try and help.
        
        Laurence
        
        Auxiliary oil feed
        
        Posted By : John Davies, 16-Feb-2003, 11:13pm
        
        Laurence,
        Let's NOT fight!
        
        Of course you are correct about the origin of the words. But words acquire additional meaning when used for specialised purposes.
        In a flow system, an orifice - defined as I suggested - alters flow in a different way to a restrictor. Orifice flow depends on density, rather than viscosity and will, at a lower flow rate than a restriction, change flow from laminar to turbulent. In turbulent flow, the flow rate will depend on the fifth rather than the fourth power of the radius.
        
        There are too many variables! I CAN'T help anyone to choose an appropriate size of restrictor for their external oil feed - I wish I could, and wanted to explain why I couldn't. It needs to be measured. This oil feed is one of the perennial questions. Anyone who can measure what the feed does to oil flows should get the Triumph Nobel!
        
        John
        
        PS Laurence, I really don't want to fight; I want to help anyone who wants advice, to be corrected and learn when I am wrong, to argue and debate. But like anyone else, I prefer not to be criticised as a fool or a braggart when I make a mistake.
        J.
        
        PPS Please have the last word.
        
        Auxiliary oil feed
        
        Posted By : Laurence Cochrane, 17-Feb-2003, 10:16pm
        
        John
        
        Okay granted I was a bit hard on you there.
        
        I have no specific argument with you. You will find on my first input on this thread I actually agreed with you.
        
        As I stated "Obviously dependant on perspective".
        
        However this is too old a dog to be TAUGHT new tricks!!!
        
        Laurence
        
        The last word is PAX!
        
        Auxiliary oil feed
        
        Posted By : Alastair Campbell, 19-Feb-2003, 04:00pm
        
        For goodness sake Laurence, don't bring dogs into the debate. Your own two aren't exactly the brightest of canines. One runs about with plastic burger or squeaky fish and the other eats Dolomite numberplate light wires. Perhaps Norman could settle the argument. Do you think they have Internet access at the Baghdad Hilton?
        
        Auxiliary oil feed
        
        Posted By : James Lavery, 20-Feb-2003, 01:41am
        
        Hi John, Hi Laurence,
        
        Well,I did'nt expect a request for advice to cause such a heated exchange. Deciphering your messages I take it that the simple answer is not to fit this extra feed pipe. To Don, thanks I'll watch out for it on the message board.
        
        Thanks to you all.
- Oil cooler and auxiliary oil feed on a 1500 Spitfire
  
  Posted By : Don Cook, 24-Feb-2003, 12:56pm
  
  SPOOKY!
  
  Given the sunny weather I took my GT6 out for a blast and found, after parking up outside a pub, that I had a pool of oil under the car. The feed pipe to the rockers burst some seal or other so I took the flipping thing off. I shall now monitor my oil consumption!!