Opinions on a possible engine replacement

[rich weyand]

Another thing I'm confused about in the GM setup instructions for their performance engines:

Set initial spark timing at 10º before top dead center (BTDC) at 650 rpm with the vacuum advance line to the
distributor disconnected and plugged. This setting will produce 32º of total advance at wide-open throttle (WOT).
The HEI vacuum advance canister should remain disconnected. This engine is designed to operate using
only the internal centrifugal advance to achieve the correct timing curve.


Why would you disconnect and plug the vacuum advance? Thought this allowed the timing to advance more when cruising for better gas mileage.

That is utter nonsense. Once you set the timing, hook the vacuum advance back up, to manifold vacuum, not ported vacuum. Ported vacuum started being used in 1968 to accommodate AIR pumps. Manifold vacuum has been used since 1930 for engines without AIR pumps.

 

[68post]

Another thing I'm confused about in the GM setup instructions for their performance engines:

Set initial spark timing at 10º before top dead center (BTDC) at 650 rpm with the vacuum advance line to the
distributor disconnected and plugged. This setting will produce 32º of total advance at wide-open throttle (WOT).
The HEI vacuum advance canister should remain disconnected. This engine is designed to operate using
only the internal centrifugal advance to achieve the correct timing curve.


Why would you disconnect and plug the vacuum advance? Thought this allowed the timing to advance more when cruising for better gas mileage.

Probably a typo, no one seems to proof read the internet

 

[rich weyand]

Probably a typo, no one seems to proof read the internet

No, it's actually in the written packet you get with a new GM engine. And it's completely nonsense. BTDT.