< This e-mail address is being protected from spam bots, you need JavaScript enabled to view it writes No I disagree.  The Mk1 GT6 and Vitesse used 18-58-58-18, but the Mk2 used 25-65-65-25.  According to my Triumph data the change happened in 1971, but my old 1970 Vitesse had the 25-65 cam. (Identified by looking at the rings on the cam and checking them against Triumph data). That might make sense. The source I was using is rather sketchy on Mk1 / Mk2 differences. Also the 2500PI is a Mk2 engine (even in MK1 cars) in so far as it has the full width head, so it would be logical for it to have the MK2 cam. What the Mk3 GT6 used is anyone's guess. Early ones were, I believe, as per Mk2. But from KE10000 on they changed it. Mine's a late one I've just had a look at the data.  The 25-65 cam is number 308778. (I've still got a Mk2 cam somewhere, so I'll go and see if this number is etched on it) Chris Morriss Also at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

In article < This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , Robert Pearce < This e-mail address is being protected from spam bots, you need JavaScript enabled to view it writes In article <97+ This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , Chris Morriss < This e-mail address is being protected from spam bots, you need JavaScript enabled to view it writes I've just had a look at the data.  The 25-65 cam is number 308778. (I've still got a Mk2 cam somewhere, so I'll go and see if this number is etched on it) The Vitesse 2L Mk2 parts catalogue gives the camshaft part no as 308778. It was my understanding that with the switch to the Mk 2 the camshaft timing changed from 18-58-58-18 and became the same as the 2.5pi. However the TR5 and TR6 used a hairier profile  35-65-65-35 (until the drop to 125bhp), hence the higher power figure as opposed to the saloon. The Triumph 2000/2500 register has a very detailed site on specifications and tuning at http://www.kvaleberg.com/t2000.html Charles Jackson

I though some 2500s used the Vitesse / GT6 cam of 25-65-65-25, or was that only in the TR6? Chris Morriss Original 150HP cams were 35-65-65-35 later ones were 25-65-65-25, and IIRC the latest ones went back to the early 6-cyl cap profile of 18-58-58-18. The factory specified symetric timning, but you can usually get slightly better performance by advancing the cam 5 (crank) degrees, especially on the hotter profiles. Anthony.

I've just had a look at the data.  The 25-65 cam is number 308778. (I've still got a Mk2 cam somewhere, so I'll go and see if this number is etched on it) Chris Morriss So far as I am aware only three different camshaft profiles have been used by Triumph on their production sixes. These vary in lift, duration, and lobe-centre angle and are distinguished by the number and size of grooves machined into the circumference of the front sprocket fixing. MKI cars had the mildest camshaft with 18-58-58-18 timing and no identification groove. MKII carburettored engines had a cam with 25-65-65-25 timing, recognisable by one wide marking groove.   A lot of fuss is often made about the so-called 150 HP Cam found in TR5 and early TR6 cars. This had 35-65-65-35 timing with slightly more lift and required a different metering unit to work properly; due to the narrow centre-lobe angle and long duration it doesn't always work well on carburettors. It can be spotted by its two marking grooves; from 1972 or so it was replaced by the earlier non-PI cam. In reality the TR5 cam might be worth 5-10HP on injection, when the rest of the engine is in a good state of tune, but certainly not enough to account for the difference between the 150HP quoted for early PI cars and the later 125BHP specification. Anthony.

What the Mk3 GT6 used is anyone's guess. Early ones were, I believe, as per Mk2. But from KE10000 on they changed it. Mine's a late one I've just had a look at the data.  The 25-65 cam is number 308778. (I've still got a Mk2 cam somewhere, so I'll go and see if this number is etched on it) The Mk3 GT6 parts catalogue lists three camshaft part numbers :     308778     Up to KE10000 except US & Sweden     307621     Up to KE10000 US and Sweden     311399     After KE10000 all markets I also have 308778 listed for 2500PI Mk2 up to MG75000 and 311399 thereafter. Interestingly, 307621 is listed for the 2500TC & S. I can't find any Mk1 PI details at the moment.

So far as I am aware only three different camshaft profiles have been used by Triumph on their production sixes. I have at least four part numbers for the six cylinder camshaft, without even looking at TR5/6 parts. You may be right about the late Mk3 GT6 reverting to the Mk1 profile, but the USA / Sweden cam (also used on 2500 carb) seems to be different, as does the Mk1 2000 saloon.