Timing problems

[C10Slim]

So I started a post in the 60-66 section that started our as a gear question, but resulted in us narrowing it down to a timing issue. Basically I have lack of low end power and stumbling off idle.
http://67-72chevytrucks.com/vboard/s...d.php?t=485641

The details:

• New Blueprint 383 making 430HP and 460TQ
• Engine included Edelbrock 1407 (750CFM) carb, performer intake and MSD HEI.
• Engine was setup,dynoed and shipped with these items on it.
• I had to pull the MSD out to prime the motor. Put it back in and THOUGHT I had timmed it right.
• I tried not to mess with the carb too much but did have to take it off to intall my TV cable setup.
• New monster trans 700r4 with 2500 stall. All indications show the TV is setup correctly. Used the TV made easy kit and a guage.
• Confirmed the rear has 3.73 gear.

All this considered I think it should be pretty dang peppy, but it's not. Hard to start and keep running until warm. Even after warm driving around it just doesn't have the power I would expect. I think my daughters go kart would pull away from me. It stumbles when you gas it off idle and then it picks up, but still not 400+ HP worth. So I thought I must have a really low gear or something. We have since determined that is not the case.

So, this led us to timing issue. Today I plugged off the vac ports and started her up. It would barely run the rpms were so low like 300-400rpm. I put my hand on the linkage and brought it up to about 800-850 which should be a good street idle. Well I had 4* ATDC. Yes you heard me, 4* AFTER TDC. I don't know what happened there. So just for chuckles I hooked the vac line back up and checked timing again. At idle I get 12* advance and at 3500 I get 36* advance which is just about right per the engine builder. The only thing I cn think of is maybe when we initially timed it, I had the vac advance on and thought "oh it's damn near perfect."

Anyway, now my question is... If I go back and reset the initial timing with out vac to 12* is that going to push the total timing way out of spec when I hook vac back up?? Meaning I am going to have to push initial timing from -4 to 12 so is that going to add 16* to the total timing making it 52!?!?

Thanks in advance for you help!