b motor dist vacum line to?

[funnycar]

silly question I should know this but having a brain cramp
does the vacuum line to go the metering block or the base of the carb port?
holley 750 dp

 

[snakeoil24]

it goes to ported vacuum above the throttle plate

 

[D575]

it goes to ported vacuum above the throttle plate

Does it ? This is a good read.
http://moparforums.com/forums/f7/ported-vs-manifold-vacuum-9275/


For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively. Don't ask Summit or Jeg's about it – they don’t understand it, they're on commission, and they want to sell "race car" parts.

 

[funnycar]

thanks for the quick replys

 

[A383Wing]

Stock factory Mopars in the 60's through the late 70's were connected to ported vacuum. If you try to run a distributor that was made for ported vacuum and change it to manifold vacuum, you are gonna need to do some changes on your dist curve and reset yer timing.

check yer factory service manual for proper vacuum line connections

 

[Photon440]

Checking my 1970 Plymouth shop manual, I can't find the vacuum line connections listed. However, the section for setting timing mentions disconnecting and plugging the vacuum line before checking initial timing. To me that indicates that there is vacuum there.

As part of 1970's CAS, some 383 and 440 engines did use a vacuum retard solenoid that kicked in when hot and idling, something that wouldn't be needed with ported vacuum.

 

[D575]

Checking my 1970 Plymouth shop manual, I can't find the vacuum line connections listed. However, the section for setting timing mentions disconnecting and plugging the vacuum line before checking initial timing. To me that indicates that there is vacuum there.

As part of 1970's CAS, some 383 and 440 engines did use a vacuum retard solenoid that kicked in when hot and idling, something that wouldn't be needed with ported vacuum.

did you read the article ? Do you have all the smog on your car ?

 

[snakeoil24]

Does it ? This is a good read.
http://moparforums.com/forums/f7/ported-vs-manifold-vacuum-9275/


For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively. Don't ask Summit or Jeg's about it – they don’t understand it, they're on commission, and they want to sell "race car" parts.

D575 you are right I have been working on my son's 1988 Chevrolet Monte Carlo and his engine uses ported vacuum. I forgot this was all emissions motor crap.

 

[Photon440]

did you read the article ? Do you have all the smog on your car ?

Yes, I read it, quite some time ago. And fully agree with it. I'm just wondering where the factory pictures of vacuum connections are. I also realize that whatever the factory does is usually conservative and for the average driver plus emission considerations, and not optimal for actual performance and drive-ability with premium gas.

About the only smog on my car is the PCV valve. Being an air grabber car, it doesn't even have heated intake air.

 

[67 coronet]

the article is interesting but a bit missleading.first its from a corvette guy,of all things,and we all know how they are.his ideas are sound,but he dosnt get the mods across correctly in his descriptions.he is talking about changing the vac advance to a vac retard device.where as this will work well,it takes a good amount of mods to make it work.you just cant stick the dam vac advance to the manifold,time and go with it.even he mentions a diff vac advance part # but that is for a chevy!

 

[coloradodave]

I originally posted that article on this site. I don't think we read the same thing. You CAN just hook the vacuum advance to the manifold AFTER setting initial and total timing to specs. Your advance can may have too much advance built in (I've seen as much as 22*), so if that's the case, you just get a can with adjustable advance. The can the author noted was for a GM car, but , as you stated, it was on a Corvette site! Like the article stated, the ported vacuum didn't come into existence until the emissions motors made their debut. The vacuum cans on all my cars in the 60s were hooked to full manifold vacuum, as is my max wedge today.

 

[A383Wing]

all my 66-70 Darts & Chargers were ported vacuum distributors.....no emissions

 

[62MAX]

I originally posted that article on this site. I don't think we read the same thing. You CAN just hook the vacuum advance to the manifold AFTER setting initial and total timing to specs. Your advance can may have too much advance built in (I've seen as much as 22*), so if that's the case, you just get a can with adjustable advance. The can the author noted was for a GM car, but , as you stated, it was on a Corvette site! Like the article stated, the ported vacuum didn't come into existence until the emissions motors made their debut. The vacuum cans on all my cars in the 60s were hooked to full manifold vacuum, as is my max wedge today.

-Dave,my 56 Dodge D500,my 60 De Soto Adventurer,my 65 Belvedere and everything else I have owned were ported vacuum,even my 54 Dodge Pace car convert.Every WCFB,AFB and AVS up until 70 only had one vacuum port,on the carb.The 62 300 H carb's on my wagon have one port,on the rear carb,ported !

Also,every max wedge distributor I have ever owned including what i have now were all mechanical without vacuum advance either with or without tack drive..

 

[HawkRod]

From what I have read, only later emissions engines were hooked to ported vacuum.

Although earlier cars may have had the advance hooked in to the carb, that does not mean that it was "ported" vacuum from the carb.

 

[62MAX]

Well,you may be right or you may be wrong or I may be right or may be wrong but I have a total of 15 AFB's beginning in 1958 and going to 1966,all Chrysler except two Buick from the mid 60's and seven AVS's from 68 to 70,a few junk,most good,I just made a point to drag "all" of them out and check,they all have ported vacuum.Don't know about the rest of GM or Ford but I know what I have.

 

[coloradodave]

"Also,every max wedge distributor I have ever owned including what i have now were all mechanical without vacuum advance either with or without tack drive."

I guess I should have been more clear. I run a Mallory electronic distributor with vacuum advance on my motor. I use full manifold vacuum because it drops completely out when you stomp the go pedal. With ported vacuum, as the RPM comes up you are adding more advance. How much and at what RPM will drive you crazy. I played with this a lot when I had access to a stroboscope (distributor machine) years ago. The article by the GM engineer, in my opinion, was right on for an early street/strip motor with decent compression for the reasons he outlined; better cooling and better economy. The ported vacuum does you no good while you're sitting in traffic idling. To each his own...what ever works for you is what you should do.

 

[WileE]

Although it may be "correct" to run the advance to ported, I agree with Dave in using full manifold vacuum, for the reasons he stated.

 

[A383Wing]

Ported vacuum will drop to "0" when you stomp on the go pedal as well.

 

[coloradodave]

Sorry, but I disagree. When the throttle blades open, and the air rushes into the manifold/cylinders, vacuum is created at the "ported" vacuum location. As the RPM goes up, the vacuum increases, giving you more advance. I would hope that you reread the article to see why ported vacuum even exists.

 

[A383Wing]

ok..you can disagree, that's your choice. I have put a vacuum gauge on the ported & constant nipples, both drop to "0" when floored. I have read the article, many times. Lots of mis-information in there, plus it's not for "stock" Mopar systems.