I've always used the pointers that go into the top of the dashpots. I
find that, after getting the carbs synchronized with the throttles
partly open (by adjusting the clamps), I can usually get them
synchronized at idle by adjusting the idle speed screws. Any large
difference is due to 'sticktion' in the dashpots or needle centering.
I don't see that synchronization is all that critical anyway. Even at
redline, the last 1/4" of throttle travel doesn't seem to do anything,
and my idle doesn't seem noticeably rougher until the sync is WAY out.
Of course, that could just be my engine <g>
Randall
Henry Frye wrote:
>
> Hi gang,
>
> I have been happily tuning my TR3B carbs using the "rubber hose to the ear
> and listen to the pitch of the hiss" method, until now. I won a gift
> certificate from Terry's Jaguar Parts as door prize at the Connecticut
> Triumph Register car show last year. Since I didn't need any Jaguar parts I
> bought an Air Flow Meter. Same principle as a Unisyn, but there is a meter
> instead of the floating balls.
>
> Since the air cleaners came off today to get cleaned and oiled this was an
> excellent opportunity to try the air flow meter. The carbs were pretty
> close from last year. I loosened the coupler assembly, that accordion
> pleated joint that connects the two carbs. I then dialed the carbs into
> perfect unison, and tightened the coupler assembly.
>
> Then I opened the throttle a crack and got the RPM's up to about 2200 on
> the tach. I adjusted the Air Flow Meter for more air, and measured each
> carb again. As I suspected, the carbs are now out of sync. The meter read
> 10 on the rear carb, and 14 on the front carb.
>
> The accelerator linkage on a TR3 acts on the front of the front carb's
> throttle shaft. There are two of these coupler joints between the carbs.
> There is undoubtedly some slop in the couplers, and as a result, the carb
> butterflys are in sync at idle, but not once you crack the throttle open.
> The front carb is pulling more air.
>
> It appears I can't get perfect synchronization at both idle and at speed.
> Then, what is the optimum setting? Split the difference so both idle and at
> speed are somewhat sacrificed? Or sacrifice the idle and go for perfect
> synchronization at speed??? It would seem that being in sync at idle and
> being farther out of sync with the throttle open is not the best way to set
> it up. If this was a race car, I know that answer. ;-)
>
> I think the accelerator linkage attachment point moved from the front of
> the front carb to between the two carbs on the TR4 or thereabouts. This
> would certainly be a major improvement...
> - - - - - - - - - - - - - - - - - - - - - - - - - -
> Henry Frye - thefryes@iconn.net - Connecticut, USA
> Stag MkI Getting Sorted Out
> TR3B Driver
> TR250 X 3 The BIG Project - Will Be Worth the Wait
> Homepage http://members.iconn.net/thefryes/
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