If you can't find any external vacuum leaks, it could very well be due to an internal leak in one of the carbs, depending on exactly what carbs are fitted. For example, if they have throttle plate bypass valves, one could be sticking open and would give high idle and low vacuum. Some have the internal decell valve diaphragms, different flange spacers/gaskets etc.
Can you drop the idle if you back the idle screws out all the way?
Glen
--Previous Message--
: Thanks Glen,
:
: If I run the engine up to temperature
: one more time would you advise
: re-torquing with the engine hot or
: cold? Obviously if hot I will need to
: leave the cooling system
: "open" so there is no
: pressure on the water jacket. Your
: advice is most appreciated.
:
: The curious thing about the vacuum is
: that the OLD worn out cam did this with
: the the engine before rebuild. That
: old cam was supposed to be a
: performance item but my father-in-law
: did not know anything about the grind.
: I always blamed the previous low vacuum
: on that cam. Since the low vacuum is
: still present, I now suspect the carbs
: and/or manifold. I made sure the
: manifold surfaces were flat and I am
: using a new manifold gasket. Previous
: attempts (prior to rebuild) to find
: vacuum leaks revealed nothing. What
: else can cause such low vacuum
: readings?
:
: Doug L.
:
: --Previous Message--
: With that low vacuum, there is no way
: to
: tune it properly. Hope it's something
: simple like just a leak...
: Re re-torquing, that was normally done
: on the PDI (pre delivery inspection)
: when the car was sold new from the
: dealership. That step was often
: overlooked, for obvious reasons, and is
: partly to blame for some of the
: legendary head gasket
: "problems" that some of these
: cars had.
: With a composition gasket, I do it
: after the initial shop run period,
: 15-20 minutes, then again after
: ring-seating driving and a half-dozen
: heat cycles or so.
: Yeah on some engines it is a real PITA,
: but this is a VERY important step...
: Glen
:
:
:
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