Sunday, April 26, 2009

Off with its head!

After a Parts Department sort out at my father's place in NZ, there's a pallet of parts due to arrive in Brisbane late next month. I uncovered a lot of bits opportunistically grabbed over the years, many cleaned, repainted and wrapped in newspaper before being put away and mostly forgotten. The pallet includes a Type 9 gearbox, new 23-spline clutch, Subaru diff, Triumph Tune 330lb/in springs (I 'd go for 450lb now but hey), NOS Monroe Herald rear shocks (which may fit the GT6, I'll wait and see), and shiny front wishbones and turrets.

One box contained 6 cylinder engine parts, as I originally planned to put a PI engine in my Herald coupe. I uncovered VP2 010" main and big end bearings, new valve guides, gaskets and a timing chain tensioner. I also dug up an 'F16' camshaft from Kelford Camtech in Christchurch. It's the same grind as in my 13/60, and certainly made a difference to a friend's 2000 Mk2:

Valve lift: intake 0.426, exhaust 0.422
Duration at 050: intake and exhaust 220

The TR5, by comparison, has 0.372 valve lift and 226 duration (http://www.hottr6.com/triumph/tr6cams.html), so less lift but slightly more duration. A longer duration cam may be worth trying at a later date, but for now I'll build it with what I've got.

I took the head off the GT6 motor today to see what lurked beneath. It's a low compression US-spec engine, and turns out to have flat pistons in a recessed block, and the head casting - 312388 - and machining numbers - 218255 - are the same as Mk2 PIs, 2500TCs, as well as the GT6 Mk2, which had domed pistons to raise the compression. The head numbers indicate a height of 3.400" compared with 3.300" for the flat-pistoned Vitesse Mk2, so it'll need at least 100 thou shaved to get the compression up.

The pistons can be moved around in the bores, so a rebore is on the cards. 60 thou forged maybe? Interestingly, the outer 4 are stamped 'A' and the inner two 'B'. The photo shows the recessed bores - it looks like the head gasket's still in place, but that's the step in the block!

1 Comments:

Blogger Gareth said...

took the step out of my block made it nice and flat and took the bores to 60 tho more so thats all ok.

7:31 am  

Post a Comment

<< Home