Another timing question

[68conv4sp]

Based on the recent timing discussion, I set the timing on my 68 289 (8.7:1 comp ratio, 91 octane) at 750 rpm, 15 Deg BTDC, which yields 37 Deg, all in at 2900 rpm. This is with the vac line disconnected. With it connected the result is: 800rpm, 17 BTDC, and about 55 Deg at 3000 rpm w/ no load. It drives fine w/ no pinging (glass packs make it hard to hear though). Sound right?

 

[danny clemens]

Did you plug the line after removing it? That can make a difference. I'd back it up until it started idling slower and then take it back up to the place it started idling the fastest and then check it.

 

[68conv4sp]

Yes they were plugged during initial advance set up.

 

[Jonstantine]

55 seems really high, but its been several years since i messed with timing

 

[10secgoal]

Hell if you can run it GOOD. It won't be 55 under a load.

 

[68conv4sp]

Hopefully it drops to about 39-40 Deg. under load w/ vac connected. My engine is a '68 w/ the 63cc lower compression heads (8.7:1) so I am pushing the timing a little. I also run a 160 deg. thermo and 91 octane, which should, in combination, allow for some aggressive advance.