Section : Engine

Engine identification

Posted By : Colin Wake, 30-Dec-2005, 02:56pm

• Engine identification

  Posted By : Mark Baldock, 30-Dec-2005, 03:08pm

  Hi Colin
  
  Yes, as far as I know the prefix MM is either a 2.5S or a 2.5TC.
  
  Regards
  
  Mark

• Engine identification

  Posted By : Chris Taylor, 30-Dec-2005, 05:39pm

  Canley Classics web site has a list of all engine prefixes. Looking at that it seems that MM is the 2.5 TC (ie 99bhp rather than the later 106bhp 2.5S). Can't recall whether there is a different cam or it's just a matter of bigger carbs on the S.

  • Engine identification

    Posted By : Colin Wake, 30-Dec-2005, 08:23pm

    Mmmmmmmm
    
    More investigation needed.
    
    Will try to get and have a look after New Year.
    
    Cheers!
    
    Colin

    • Engine identification

      Posted By : David Rumens, 20-Jan-2006, 05:15pm

      I agree with Chris the prefix MM is the 2.5 TC or S saloon. This engine was designed to meet the tight emission reg of the late 1970's as a result the BHP is quite low for the capacity. It is a straight forward matter to increase the BHP by changing the cam and the needles/springs in the carbs. Skimming the head to raise the CR from 8.5:1 to 9:1 will also help, though a CR of 8.5:1 does help when using 95 octane fuel.
      
      

      • Engine identification

        Posted By : Colin Wake, 20-Jan-2006, 08:24pm

        So what sort of BHP could I hope for with a skim and a new cam??
        
        

        • Engine identification

          Posted By : David Rumens, 21-Jan-2006, 04:16pm

          Use the Mk2 Vitesse/GT6 cam. The standard cam fitted to the MM engine with a timing of 10/50/10/50 it is more suited to the 1950's! The needles either use BAE and Green Springs. or for less power but more MPG use BDM needles. The BHP is 125 to 130 and torque around 150 ft/lb. Any more and the diff goes bang! In a Gitfire this will give 120 + MPH and zero to 60 between 7 and 8 secs.
          

          • Engine identification

            Posted By : David Rumens, 21-Jan-2006, 04:40pm

            Colin, Forgot - You also need a Mk11 Dizzy to match the cam. If you do use one then either disconnect the vacumn unit or replace it for one with half the advance. This is because on half throttle the vacumn unit advances the timing to far for 98 octane fuel. Lots of pinking!
            
            One of the vacumn units functions is to improve the MPG, it achieves this by advancing the timing when you have a light load on the engine i.e. cruising conditions, half throttle. This give a better burn of the fuel, but there are limits to the amount of advance that can be used as it is limited by the fuel octane rating used and tune of the engine. No 101 octane hence problems. You can retard the ignition timing but you will lose power and torque in the process.