libertyc wrote:
> So, now I am almost positive it is carb related.
> Here's why I believe that is the case: I was able to heavily restrict
> (with my hands) the amount of air going into the carb intakes and get it
> to run much better. The rpms would raise from 800 to approx 2000, and
> miss would almost disappear.
Hmm... I may be missing something, but the only reasons I can think
of that the air pull would be drastically less in one carb than
the other, would be either the throttle butterfly valves are
open widely disparate amounts (throttle linkage mis-set), or one
of the carbs has a major vacuum leak.
Random possible ideas follow:
Have you tried balancing the airflow between the carbs? To do
so, you'll need to loosen the throttle linkage between the carbs.
(When you rebuilt them, was the linkage disconnected and then
balanced when reconnected?) For more info on balancing
the airflow, see http://www.vtr.org/maintain/carbs.html
Check both carbs for torn air valve diaphragms.
When the carbs were rebuilt, did you disassemble the temperature
compensators? Could these have been taken apart in a prior
rebuild? If these are radically mis-set, you will get a big
air leak. Instructions on setting these can be found at
http://www.vtr.org/maintain/temp-compensators.html
Do the air valves move *very* freely up and down within the
carbs? If you had inadvertantly swapped these in the rebuild,
one could be tight, and quite resistant to moving. Same goes
for inadvertantly swapping carb covers. Do both carbs have
damper oil in them? Are the damper rods straight? Do they
seem to work correctly? The above can questions can be
readily checked with the air cleaner off, and engine off.
Lift the air valve with a finger, and ensure that they resist
upwards flow, but drop back down quickly.
The above ideas are about all I have. I had a really
nasty problem to debug with misses under load when the
engine was partially warmed up. They turned out to be
the result of a broken throttle spindle coupling, which
had about 30 degrees of play when turned in one direction,
but not the other. The result of this was that the front
carb butterfly would open about 30 degrees more than the
rear carb butterfly. This would only cause a major problem
on my rich-mixture TR6 when the engine was under load,
partially warmed up. (It would be fine cold, or hot, but
miss occasionally after about 10 minutes of running when
pressed.)
--ken
'74 TR6 Daily Driver, registered, inspected, insured, and
ON THE ROAD AGAIN TODAY!
...looking forward to 31 consecutive "British Car Weeks"
til Thanksgiving!
--
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
|