Dave Barrans writes:
Any relation to Dan Barrans?
>Our current problem is this: it sound and runs fine at idle, however under
>a load it has very little power and backfires on deceleration.
>Timing set a 4 degrees.
>After we rebuilt & timed the engine the power was fine. It passed all the
>Washington State emissions criteria except for "CO2 at idle". Since we had
>not adjusted the carbs, we took it to a "British Specialty" shop. They
>changed the timing and adjusted the carbs. When they were finished, the car
>had "no power and ran rough". Upon review we discovered they had set the
>timing incorrectly. We reset it to 4 degrees. STILL NO POWER!!!
I don't trust dynamic timing on old LBC's. They have too many vacuum
leaks. I timed my '6 (which ran ok at RPM, but tried to stall when stepping
on the throttle) by just advancing it until it was happy. What is it set to
now? I dunno, and don't care - it runs fine, and doesn't ping.
One thing to check for - split diaphragms in the carbs. You can test
the advance & retard by sucking on the vacuum pipes. (Note that they may
be full of gas vapor - I used a plastic bag to avoid a mouthful of fumes.)
>One more, is the timing supposed to be ATDC or BTDC? I set it after the
>rebuild to BTDC and it ran fine, but it looks like the Bentley book calls to
>ATDC. ATDC seems strange to me.
>Best Regards,
It's ATDC. The timing on the 6's is good for emissions, bad for power.
But that assumes that a) idle is correct speed, b) vacuum retard is working
correctly. If the retard is bad/failed, you'll end up way too retarded at
speed if you set it to 4 ADTC at idle.
--
Randell Jesup, Scala US R&D, Ex-Commodore-Amiga Engineer class of '94
Randell.Jesup@scala.com
#include <std/disclaimer>
Exon food: <offensive words censored by order of the Senate>
|