Postby Hasbeen » 19 Oct 2007 00:08
Holt, I have had both US, & UK spec 7s. My UK spec car has good air
filters, & richer needles, in its SU carbs, but is otherwise stock.
The difference is chalk & cheese, with the UK car at least 20% up to
25% more powerful.
The difference is over 2 seconds in a standing quarter mile, but its
in the driving that it realy shows. I have a long, moderately steep
hill out of my local town. My UK spec 7, will accelerate from 80Km
to 100Km [48 to 60 MPH] up this hill. The US spec 7 slowed from
100Km to 94Km up this same hill, on full throttle.
I also get better fuel economy from the US spec car. Probably
because I'm not on full throttle all the time.
The local Triumph guru mentioned in passing the other day, that it
was pretty easy to get 130 BHP out of the 7 engine, [cam, head job
etc] but only if you shaved the daylights out of the head. He
reckoned you needed at least 10.25 to 1 compression ratio to get
that improvement.
He also mentioned that he could find no advantage with the SU carbs
against the Zenith, US spec carbs, other than the ease of
maintenance of the SUs.
My memory of all my 10+ to 1 compression ratio cars in the 60s,
[when we had 100 octane petrol to suit them] is of cranky cars,
overheating in traffic, & being a bit of a bugger in general, but
my 9.25 to 1 TR7 is great.
Hasbeen
PS. Check that the UK & US cams are not different. You could be
dissapointed with any improvement if the US cam is milder.
That Triumph guru uses Mitsubishi Magna pistons, with the valve
recesses machined in them, in competition 7 engines.
Hasbeen
