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Old 09-04-2004, 05:41 PM
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Vacuum advance from my carb to Dist.Do I need it?

I was at my local engine building shop yesterday....The Guy took a look at my engine(350 crate) and asked my why I set it up that way?I'm like what are you talking about.He pulled off the vacuum hose off the distributor going to my carb(edelbrock 600cfm).He tossed it.He said you don't need that....I promise on my life.He said.He made a new vacuum line and connected both ends to the carb.What is his reasoning behind this???These guys at bayshore engine rebuilders are top notch but impatient with an amature like me.He's last words trust me you won't regret it.Sorry his last words were don't let anyone talk you into doing something else.Not sure who to believe here.Car seems to run fine.Help!!BM
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Old 09-04-2004, 06:06 PM
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A street engine needs vac. advance. you will experience loss of gas mileage at the least. Usually low end throttle response. Even with a curve kit. The vac hose should be connected. I use non ported vac from the base on hot cam cars.
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Old 09-04-2004, 07:38 PM
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You'll also get a little smoother low-rpm running with vacuum advance, whether on the street or in the pits, & it may help prevent overheating, especially when hooked up to manifold (not ported) vacuum.
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Old 09-05-2004, 05:48 AM
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I tried that (none ported ) from the dist. and experienced slight backfires out of the exhaust. Hooked it back to ported and works great.
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Old 09-05-2004, 06:53 AM
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Yeah man hook it back up, it's there for a reason.
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Old 09-05-2004, 07:15 AM
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Re: Vacuum advance from my carb to Dist.Do I need it?

Quote:
Originally posted by batman09
...He pulled off the vacuum hose off the distributor going to my carb(edelbrock 600cfm).He tossed it.He said you don't need that....
I think I'd look for another shop to do my work. Street engines need vacuum advance, period. Especially Chevys. Chevys for some reason are a little more sensitive to vacuum advance than other brands and will tend to overheat in traffic if it's not used. Trust me, been there, done that.

If you're using your car for racing and drive it only occasionally on the street you can get away with no vacuum advance but the proper way to do that is to replace the distributor with a non vacuum advance unit or have your current distributor recurved and modified to remove the vacuum advance setup.

Centerline
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Old 09-05-2004, 10:47 AM
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Do you know how much advance the can adds? Mine added 17* - every time I hooked it up the motor would "fight" itself, it felt sluggish at part throttle and would lose .2-.3 on the ET's. That's with 14* initial and 35* total mech advance (all in by 3000). The can would put it up to 52*. I realize it shouldn't affect WOT but it did. A can with less advance would probably be the correct fix but I disconnected mine with no problems (didn't want to spend any $$$) - the vac. adv. only added 1-2 mpg anyhow.
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Old 09-07-2004, 08:59 PM
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Real simple and relatively inexpensive solution to having too much vacuum adv. from the stock unit........use a Crane Adj. Vacuum Adv. kit!!

You could also limit the amount of advance that you get from the stocker by installing a small plate. You'll need access to a MityVac or similar, to see how far you can go....maybe use a Sharpie and mark off several degrees. I'd probably shoot for 8-10* or so from the vac. can, in addition to an initial of 10-12* or so.

Personally, I'd go the Crane route!! Much simpler!!
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Old 09-07-2004, 09:11 PM
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i had this argument with a guy once. not only about advance, though. he heard from a guy who knew a guy....ect., that you didn't need all those vacuum lines under your hood. pull this, plug that, get rid of the delay valves, thermal valves..... on a stock engine, this stuff is engineered to keep the engine running properly. air door on the air cleaner, vacuum advance, it's all the same. i'd tell that "engine guy" that the vacuum controls on the stock engine were engineered to be there by someone smarter than him!
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Old 09-07-2004, 09:22 PM
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BTW.....unless you're using a functional EGR valve, you should be using full manifold vacuum!! If you have the EGR valve - go with the ported fitting on the carb.

With full manifold vacuum, make sure you either limit the stock adv. can or go with the adjustable setup!!
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