Vac Advance - Yes or No?

[farm truck]

My 1970 GMC C2500 has a 350 engine with a HEI distributor and a Holley Sniper.
My buddy is a wrench at a classic car shop and helps me out once in a while. First time that he looked under the hood he called me an idiot for not having the vac advance connected (the previous owner swore that is ran better with it disconnected). So I hooked it up (this was a previous distributor, by the way). Ran fine either way, in my opinion.

When said wrench helped me install my Sniper I was again chastised...... for having it connected! It has been unconnected since the Sniper install & runs fine. The nipper on the Sniper is capped off, of course.

I love my buddy, but he smokes weed by the bushel and I attribute his flip-flopping to his copious intake of legal California hi-test!

She runs good..... but would she run better with the vac advance connected?

I am going to give it a try regardless...... but wanted to ask the wise sages of this board for their opinions.

Thanks in advance!

Chris

 

[Matt69olds]

I ram my sniper the first year with the HEI and vacuum advance functional for the first year while waiting on Holley to release the Oldsmobile version of thier distributor. It worked just fine.

If the distributor has an advance curve that works well, run it with the advance connected.

 

[75gmck25]

Vacuum advance is mainly there to get better gas mileage at cruise on the highway. It usually has minimal effect on acceleration and general performance. You are giving up cruising speed gas mileage, but that’s your choice.

 

[Ricko1966]

I agree with your buddy. It will pull in more timing at idle to clean up the exhaust, and run cooler,the plugs will stay cleaner and you'll get better milage. Go open the hood on 1000 American made cars made after mid 60s hell even earlier than that,they are all going to have vacuum advance. The automakers put them there for a reason. Do your own research, Google it. One more thing IDK how many cars have been made with vacuum advance on them but if GM could have saved 1.00 per car not having it,they'd have saved millions. Look at the vacuum arrangement on the trucks after about 1980 or so they have a thermo switch that if the engine starts to get hot it switches to manifold vacuum,from ported vacuum to cool them down.

 

[Rusty Nail]

*looks around*

Wise sages? I don't see nuthin.

 

[SirRobyn0]

Like everyone else in the thread has said run the vacuum advance. There is no good reason on a street driven car not to have it connected. Rick gives a good list of the benefits of having a functional vac advance.

 

[Radiohead]

Vacuum advance? Please.

 

[Ricko1966]

I didn't read all of this actually never saw before. I told you look on Google this was the first article to pop-up. As far as I got into,I think it will explain to you the advantage of running it. Not sure if that article mentions it and I didnt see where anyone else brought it up. But in high gear at moderate speeds your centrifugal advance is going to fall out,because the engines not spinning fast enough to keep the weights out. The vacuum advance will bring this timing back in because you will be in a high vacuum situation. Read this article.https://www-motortrend-com.cdn.ampproject.org/v/s/www.motortrend.com/how-to/1601-everything-you-wanted-to-know-about-vacuum-advance-and-ignition-timing/amp/?amp_gsa=1&amp_js_v=a9&usqp=mq331AQIUAKwASCAAgM%3D#amp_tf=From%20%251%24s&aoh=16888794800200&referrer=https%3A%2F%2Fwww.google.com&ampshare=https%3A%2F%2Fwww.motortrend.com%2Fhow-to%2F1601-everything-you-wanted-to-know-about-vacuum-advance-and-ignition-timing%2F

Everything You Wanted to Know About Vacuum Advance and Ignition Timing

Unplugging your vacuum advance is costing you mileage and efficiency. We help explain ignition timing and that little silver can.

www-motortrend-com.cdn.ampproject.org

 

[GTX63]

I had one not long ago where the centrifugal weights were staying out due to weak springs. It was an original high mileage distributor. I just thought it was worth mentioning.

 

[farm truck]

I ram my sniper the first year with the HEI and vacuum advance functional for the first year while waiting on Holley to release the Oldsmobile version of thier distributor. It worked just fine.

If the distributor has an advance curve that works well, run it with the advance connected.

I will get some 3/16 tube and try it today - HEY! nothing ventured nothing gained!

 

[farm truck]

VACUUM ADVANCE IT IS! Thanks everyone.

Heck, once my buddy sobers up he'll probably say the same thing

 

[farm truck]

I had one not long ago where the centrifugal weights were staying out due to weak springs. It was an original high mileage distributor. I just thought it was worth mentioning.

The original HEI blew up completely and left me on the freeway!

 

[farm truck]

Vacuum advance on - RUNS GREAT! Sending my buddy to rehab!

 

[Rusty Nail]

The original HEI blew up completely and left me on the freeway!

Pix?

And they don't call it "dope" for nothin.

 

[farm truck]

Sorry, my wife said the old HEI was stinking up the joint, so I tossed her..... the distributor, not the wifer!