Looks like this didn't make it to the list the first time, so trying
again -
I guess I should explain that my motor is modified with P&P head with
modified guides and valves, GP2 cam, 9.3:1 compression, K&Ns, etc. I
went to the SUs as they are easier to tune for modified engines (vs ZS
carbs). I have so far not found an easy way to pick a needle that suits
modifications other than trial and error. The O2 sensor really helps in
tuning, but it really only helps to give you an idea of your mixture but
not what station of the needle needs to be modified and by how much.
The needle programs that are out there really help, but trial and error
with different new needles can get pretty expensive. Burlen has needles
available, but at about $30/pr + shipping, that's a lot of time and
money (and I'm a cheap, impatient guy! lol!). I guess I'm also a bit
anal as I want to get the mixture right, not just close. My float issue
may be causing some of my problems, so I need to get that straightened
out also -
I spent a good deal of time modifying needles for an HIF4 conversion on
my Spitfire. The motor has been modified also with P&P head and other
mods, and the fuel mixture was way off. It ran rich down low but very
lean at speed and acceleration. It was interesting to watch the O2
meter go from rich to off-the-scale lean when it hit ~3200 rpm. The car
just stopped accelerating and sort of hung there and then would slowly
accelerate again. Spent a good bit of time on the needles, and when
they were right, the car ran very well. Even mixture on acceleration
stayed on the rich side. It really opened my eyes to what a properly
tuned car could do, and I know I can achieve that with the TR6.
Besides, I don't want to become one of the rice rocket tuners that bolt
go-faster goodies on and go, without having any idea of what they are
really doing <Nomex on > :). Something about building/modifying
things yourself and seeing it work makes all the difference. Maybe it's
the engineer in me . . . lol
Dale
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