panos

A short blast after i installed the 300+ ignition box, rejetted the carb and adjusted timing,only problem that i have is that i cant attach th vacuum advance because strange things happens like it shoots from the exhaust at part throttle so i left it out for now,base timing is 12btdc and total 30btdc at 3000rpm.

http://www.youtube.com/watch?v=VhvY757AhCs

citcapp

Very cool, do you have the vacuum advance connected to ported vacuum at the carb or to manifold vacuum. Should be to ported vacuum at the carb

panos

I had it on manifold vacuum,i can try ported but im a little afraid that is gonna ping,this motor doesnt seem to like too much advance

citcapp

Try the ported and let us know what happens, may have to change the spring rates in the distributor

71 Cutlass

interesting video on ported vs manifold vacuum. Old timer says always use manifold vacuum not ported b/c that's the way all muscle cars were always done until "Emssion engines" requirements were placed on engines.

http://www.youtube.com/watch?v=Gj2ut...BD20013E579A63

Start at 40 second mark.

Lady72nRob71

Mine is 'improperly' set on manifold vac but she runs too good to move anything....

71 Cutlass

Or, "properly" set up as the guy in the video believes.

panos

That is a big debate that is going on for years,im for manifold but thats just me,maybe it depends on the motor? who knows,but just a question as we all know when you set your initial you have to unplug the vacuum right? if the right way is ported vacuum why should you do that? there is no vacuum at idle on the ported side and it doesnt change a thing since the throttle blades are closed

Lady72nRob71

Right!
I created a debate on this point several years ago.
Most of the "old timer" mechanics said to use manifold vac. I knew their collective experience must say something.
I think there are a little less emissions when used on ported vac (or something like that).

panos

Here is an intresting article

https://classicoldsmobile.com/forums...tml#post247099

71 Cutlass

I've posted that article here before as well. Just another confirmation that cars have used full manifold vacuum, until the gov. wanted less emissions polluting the air (1973 or so) so ported vacuum was mandated by the gov. Ported vacuum is about polluting the air less, not the performance of a vehicle.

cutlassefi

I disagree. If your distributor is curved correctly then the vacuum advance is solely to optimize the spark timing for light load cruise for the most part.
Even on my EFI at normal operating temp the spark map reflects an increase in timing at cruise only. However there are benefits by being able to add spark for cold running as well as removing it at various loads and rpms here and there.

ziff396

Mine hates ported vacume. I have to really crank up the idle for it to run, and still is to rough. Plug into manifold vacume and it runs great. Aftermarket cams etc. change alot of things. I'm set up @17 degrees initial and 37 all in @ 3k. Edelbrock heads. Lunati Vodoo 60803. From what I have heard and have found, Edelbrocks like a lot of timing. Actually @20 degrees initial it starts at almost the bump of the key, however, I am not that brave to leave it that far ahead. No ping to date. JMO. EFI, I respect your experience. Just had to add mine with my engine.

71 Cutlass

I'll stick with what works best...and with the old timers who lived "back in the day."