Well, I started putting the engine back together in the weekend. For those
who followed the earlier posts regarding reprofiling the camshaft &
headwork, here's an update:
I eventually decided to go for the TR5 / early TR6 PI "S2" grind as this
seemed to meet my requirements for a "fast street cam". A local cam shop had
the specs already, completed the job (including cam followers) in 24 hours,
and appear to have done it well. Cost was $NZ200 ($US140). I costed out
getting an exchange cam from TriumphTune in the UK as someone suggested, but
the return airmail from NZ would have cost more than the cam!
The head has been ground out around the inlet valves, stainless steel valve
seats and bronzed guides fitted, & inlet/exhaust ports de-slagged. A head
plane has boosted compression up to around 10:1 which the cam people tell me
is the minimum necessary to take advantage of the more eccentric cam profile.
Reassembly is going OK, but I'd appreciate the group's input on a couple of
questions:
1. The distributor drive shaft has two cog wheels on it - one which drives
off the camshaft, the other drives the distributor. Both of these are a
little loose on the shaft - it appears they are only held in place by a pin
driven through the shaft axis and with time and wear this pin now allows a
bit of rotation around the shaft. My concern is that this movement must have
an impact on the timing, and also must eventually result in the pin being
sheared off.
Anyone had any experience of this? Should I replace the entire shaft or fix
it? Unless any other ideas come forward I will probably drill out the pins
and substitute them with something appropriately hard.
2. Here's a question for PI experts - I have been told that the fuel
metering unit needs to be "tuned" to match the new cam profile. Any
suggestions on how to do this, or do I need to send it away to a
professional? How important is it to get this done - ie will the engine
start and run OK without it being modified?
Cheers,
Don Guthrie (New Zealand)
don.guthrie@xtra.co.nz
'74 TR6 PI
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