Glen,
I can't help with needle size, since I simply bought the whole rebuild kit
from TRF, which came with the correct needles. But if you're replacing the
needles due to a rich mixture, you ought to also replace the jets, which can
wear out too. The hole becomes oversize. An indication of a too-rich
mixture can be that you can't adjust the idling speed down as slow as the
books say. I couldn't adjust mine below 1000 rpm, no matter what I did.
The problem can also be caused by worn shafts and bushings, allowing air to
get in. I sent mine out to Apple Hydraulics for machining, and new bushings
and shafts put in.
Sumner Weisman
62 TR3B
Date: Wed, 03 Mar 1999 08:12:26 -0800
From: Glen Murdoch <glen.murdoch@gat.com>
Subject: SU Needle Jets
After about 5 years I have finally started up a '62 TR4. After doing the
initial tuning I find the engine to be running rich (as determined by the
smell of unburned hydrocarbons, spark plug condition, and exhaust rhythm.
The mixing nut has been fully adjusted up. So I'm thinking the next step
is to change to a leaner needle.
Which brings me to my question do I want to go with (SL)s or (RH)s (moss
catalog designation). Currently I have (SM)s installed. My first thought
was to use the (SL)s but they appear to be shorter than the (SM)s which
would allow more fuel into the mixture.
The carbs are in good shape grose jets have been installed and the float
bowl level checks out. Timing has been set at 4%BTDC per the manual, a
compression test indicates 150 on all cylinders.
Any thoughts or comments.
Thanks in advance
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