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Ported or Non Ported to the Distributor?????

4X4HIGH said:
You should be running the vacuum advance on a ported vacuum source.
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He just has to say that because he is stuck in Cali and can't pass emissions if he does it the way it was originally meant to be. :D (Sorry Scott)

I always run full manifold vacuum. It won't give you too much advance at idle, it will give the engine what it wants! It just won't pass emissions at idle as easy. The only difference between the two is the ported is shutoff at idle becuase it's just above the throttle plates, other than that they are the same darn thing. So if you engine likes more advance at idle (most likely), run it that way. If you have to pass emissions testing, well, sorry to hear that.
 
Im not sure why its hard to understand...but,

engines need to advance timing with RPM, but not go above a certain point..
 
I was told at one point in time something along the lines of "the engine wont ping (detonate) at idle excewpt for while starting. So run the timing up as far as you want at idle as long as it wont ping elsewhere and it doesnt fight the starter". The moral of the sotry was, run as much advance at idle as you want. I have also heard caddy guys say they run non ported and run about 12* of static timing bringing there idle time up somewhere in the 20+* range. That seems to hold NEARLY universally true for most old school motors, from what i have read.
 
y5mgisi said:
I was told at one point in time something along the lines of "the engine wont ping (detonate) at idle excewpt for while starting. So run the timing up as far as you want at idle as long as it wont ping elsewhere and it doesnt fight the starter". The moral of the sotry was, run as much advance at idle as you want. I have also heard caddy guys say they run non ported and run about 12* of static timing bringing there idle time up somewhere in the 20+* range. That seems to hold NEARLY universally true for most old school motors, from what i have read.
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That's about where I run the 350 in my K5 and it runs great...I run about 12* + about 8* from the vacuum advance for 20* at idle
 
thats what i love about my job, no such thing as vac advance, it's ALL mechanical.. well, it was... in the end it's about "ALL IN"... i set all my timing above 3300.... the boats runs all day at 4 g's.. i could give a flock what it's doing at idle....
 
djtejas said:
That's about where I run the 350 in my K5 and it runs great...I run about 12* + about 8* from the vacuum advance for 20* at idle
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lol I ask to many ?'s but when you say 20 idle.... My sticker on my engine says 4* BTDC at 550 rpms.... I set it at 8 thought cuz 4 was too low running. But yah a little confusion i guess cuz i thought it went down at idle.
 
My 86' is running to ported vac advance but then again it is all stock and i have already havd had my smog check so maybe i'll run it to non ported and try it out. Then come emissions time hook it back up to being ported for testing.
 
y5mgisi said:
Nothing at all wrong with sticking to factory specs. But just know that some of them were motivated by emissions.
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I just wondered if i read it right because he said 20* at idle, but then doesnt the vacuum advance increase it more after idle???
 
Oh, sorry, the vac advacne does intrease timing at idle when connected to a full vac source, but will not if hooked to a ported vac source. Set it to 12* with the vac advance line off and plugged. Then when you reconnect the vacuum advance line it should automatically bring itself up to about 20*.
 
Deuling said:
lol I ask to many ?'s but when you say 20 idle.... My sticker on my engine says 4* BTDC at 550 rpms.... I set it at 8 thought cuz 4 was too low running. But yah a little confusion i guess cuz i thought it went down at idle.
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Mine is not stock...and yes, I meant 20* with the vacuum advance connected
 
y5mgisi said:
. Set it to 12* with the vac advance line off and plugged. Then when you reconnect the vacuum advance line it should automatically bring itself up to about 20*.
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You think that would be the best for a stock 305??? For mileage purposes at the moment, not power as much. (and stock as in im pretty sure its stock inside because of the "no balls" effect it has, and excluding the edelbrock carb and intake).
 
Well if you want to get technical, If you floor it, You will loose vacuum and therefor loose the vacuum advance. So it would drop untill the centrifugal advance kicked in and would take it back up to something like 22ish* You will only ever have (as an example) your 12* base timing, 8* vac, and like 12* of centrifugal. For a total around 32* at "high" rpm, and high vacuum.

Base= all the time.

Vacuum= only under high vacuum situations like idle or cruise. NOT like wide open throttle or pulling a steep hill.

Centrifugal=Above a certain RPM.
 
y5mgisi said:
Well if you want to get technical, If you floor it, You will loose vacuum and therefor loose the vacuum advance. So it would drop untill the centrifugal advance kicked in and would take it back up to something like 22ish* You will only ever have (as an example) your 12* base timing, 8* vac, and like 12* of centrifugal. For a total around 32* at "high" rpm, and high .
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Ok I understand more now. So you think that would be good on my stock 305?? For gas mileage??
 
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