Timing related question...

[Irish_Alley]

Now that makes sense!  Hey, thanks again.   BTW, that is how I did the timing and idle rpm.

ps. wow, over 8k posts, where do you find the time,,,,and w/family!  Lord bless!

wait i have family lol.
if you look at my "stats"
you will see most my post are between 12-2am

[philo_beddoe]

Yea, amen brother!  I say if I were single I'd have a barn full of hot rods and a heavy bank roll.  But the Lord says, "Oh yeah, go ahead and try it!"   I' guess i'll stay in his will and be happy with my little project 77 Bonanza. Amen.

Have a blessed weekend.

[Irish_Alley]

yeah money is tight, but over the years ive gotten a couple good deals. none are hot rods but they do serve their purpose or they just have sentimental value

[philo_beddoe]

Yes sir, amen. I fully understand that.  Once this 77 c-10 is done, I'm just gonna drive it until something needs fixin.  My next big project will be a 63 or 64 impala or chevelle.   I just need to find one for a few grand that ain't a ball of rust.  Supersport preferred!

[philo_beddoe]

I have been watching youtube videos both in favor of and against porting the distributor vac line.  So what's the truth and why?

I have a 77 c-10, 305 4bbl.  All stock.          Thanks,,

[Irish_Alley]

read this
http://www.corvetteactioncenter.com/forums/c3-technical-and-performance/60830-ported-vs-manifold-source-vacuum-advance.html

[philo_beddoe]

Great write-up! Makes good sense, and thanks!!!  I should have looked back at your other post too and re-read it.  This one...

http://forum.73-87chevytrucks.com/smforum/index.php?topic=28857.msg241110#msg241110

[Irish_Alley]

yeah i wouldnt know much about this stuff without rich's help. he got us all started on it

[rich weyand]

yeah i wouldnt know much about this stuff without rich's help. he got us all started on it

That's just 'cause I started messing with cars before 1968, so the whole ported vacuum thing was like WTH?

BTW, you don't need to plug anything.  You can just pull the vac line off the carb, set the timing, and plug it back on.  All you need is the engine to keep turning over, it doesn't have to run great for setting the timing.

[Irish_Alley]

BTW, you don't need to plug anything.  You can just pull the vac line off the carb, set the timing, and plug it back on.  All you need is the engine to keep turning over, it doesn't have to run great for setting the timing.

Wouldn't this give you a vacuum leak and make the rpms higher than normal? At what point do you set the idle speed or do you set it when the v/a is being used?

[rich weyand]

BTW, you don't need to plug anything.  You can just pull the vac line off the carb, set the timing, and plug it back on.  All you need is the engine to keep turning over, it doesn't have to run great for setting the timing.

Wouldn't this give you a vacuum leak and make the rpms higher than normal? At what point do you set the idle speed or do you set it when the v/a is being used?

Sure, but who cares?  You are setting the timing, that's all.  The spark needs to fire there.  Got it.  As long as the mechanical advance doesn't start to kick in, it just doesn't matter.  Idle speed is adjusted once the timing is set and the vacuum advance is reconnected.

[Irish_Alley]

dont know why ive always done it the other way, make sense this way also. guess it doesnt matter if the v/a if its on ported cause its not active at idle so with it unplugged or plugged the rpms would be the same.

[bd]

...As long as the mechanical advance doesn't start to kick in, it just doesn't matter....

X2
The RPM needs to be low enough that the spark doesn't advance from the weights moving outward.  On the other hand, if the idle becomes erratic when the vacuum hose is disconnected, it's better to plug the hose.

[philo_beddoe]

One more thing.  I have to unhook the manifold vac line to the tranny modulator in order to loosen the dist clamp.  Can i leave it unhooked when setting the timing?   Thanks.

[blazer74]

Hook it back up or plug it.


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