Could be an oops here, my shop supplement says 10 BTDC static, 4
ATDC at idle . You guys are always talking 10 BTDC, so I figure
it's the same 10 (ie static) and set my 74 at 4 ATDC at idle .
Notice the manual shows 2 vac units on the distributor (for an
earlier car?). My antennas go up, so I set by ear and wind up at
10 BTDC at idle, nothing disconnected. Is this by chance the
timing spec for my stock 74?
Car idles and pulls better, the vac is now up to 16 (that low
compression on #4 is still doing its job), and best of all what I
thought was an untraceable exhaust leak noise, has disappeared. No
pinging yet (on mid grade gas).
Thanks for the lead on this one, Dick.
Mike L
60A,67E,59Bug,74TR6
----- Original Message -----
From: Sally or Dick Taylor <tr6taylor@webtv.net>
To: Michael Lupynec <mlupynec@globalserve.net>
Cc: 6pack <6pack@autox.team.net>
Sent: June 29, 2002 1:37 PM
Subject: Re: vacuum
> Mike---The vacuum reading on our motors depends on several
factors. A
> stock motor in good shape, idling at 800rpm, with the ignition
timing at
> 10 deg. BTDC should show up near 20 inches of vacuum.
> IF that's what you once had with all cylinders pulling their
fair share,
> then now having only 14 inches would be very low, with only one
cylinder
> down in compression.
> On the other hand, if you were running with a performance cam
that
> normally only pulls around 16 inches of vacuum, then 14 would be
about
> right for having one low cylinder.
> Ignition advance plays a big part in the vacuum signal, at idle.
It will
> show up low, if the timing is retarded.
>
> If your #4 is more than 30% lower than the others, suspect
broken rings
> or piston, to go with the oily plug.
>
> Dick
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