TR6 TR6 Stromberg needles

[skikir]

My TR guru says that the early b1af needles are different than the late b1af needles and don't deliver fuel well in the higher RPMs. He told me to get pre '72 needles for my TR6. Any comments?

 

[Andy Blackley]

I never heard that before. The Haynes "Weber Carburetor Manual", which also includes SU and Stromberg data, only lists one B1AF needle. If the profile was changed they would have used another letter/number designation.
Heres a comparison with the B2Y used in the TR250 and 69 TR6:
Stromberg Biased Needle

/ubbthreads/images/graemlins/hammer.gif B1AF B2Y
1 .0951 0.0967
2 0.0942 0.0932
3 0.0923 0.0905
4 0.0897 0.088
5 0.0864 0.0848
6 0.0835 0.0816
7 0.0798 0.0779
8 0.0771 0.0755
9 0.0749 0.0735
10 0.0731 0.0715
11 0.0712 0.0695
12 0.0695 0.0677
13 0.0695 0.0677

The whole numbers under the hammer are stations, which refer to needle diameter measurements taken every 1/8th inch, starting with Station 1 at the shank. The smaller the diameter, the richer the needle at any given station.
In the above comparison the B2Y is leaner at idle, but then richer at every point in the range thereafter.

 

[skikir]

Thanks! That's what I thought too. My other engine, in my spare parts car which I am planing to rebuild runs out of breath above 4K. I runs OK but just runs out of poop even with .1" milled off the head. I always thought it was probably a function of the cam. The engine in my car now turns out to be a GT6 engine and revs strong all the way up and surprisingly makes good power.