Which vacuum port on E'brock 4 bbl

[Hilljack68]

I have a '71 340 with a Mopar electronic distributor and an Edelbrock 1411 750cfm carb. I'm hooking up the vacuum advance, but I'm not sure if I should hook into the "timed" or the "manifold" vacuum port. Any ideas? Thanks guys.

 

[threewood]

You are just stirring up trouble lol.

I used timed on two motors without issue. I get my higher initial/total from the distributor so I don't have to rely on the vacuum to do the same thing.

 

[lewtot184]

factory was the timed port. that's what I use.

 

[1967coronet]

I also am using timed, my 750 eddy had a surge at higher rpm , With help from guys on here and a spring and rod change along with a smaller advance plate & using the timed port cured the surge.

 

[rumblefish360]

Where did the factory put it?
Is the factory port high or low in the barrel of the carb?
Is it the same for the Edelbrock carb? That would be were the vacuum port being used is the same in the barrel as the factory carb.
Why change from factory?

 

[toolmanmike]

Timed. The distributors aren't set up for constant vacuum.

 

[lewtot184]

Where did the factory put it?
Is the factory port high or low in the barrel of the carb?
Is it the same for the Edelbrock carb? That would be were the vacuum port being used is the same in the barrel as the factory carb.
Why change from factory?

the factory port is above the right primary throttle blade. this position goes back to pre-emission days.

 

[Ranger16]

Timed port is above the throttle plate, thus no vacuum supplied at idle (an early attempt at emission control), while manifold supplies vacuum at idle. Once off idle, they're both the same. I run mine (same carb) on manifold vacuum.

 

[rumblefish360]

the factory port is above the right primary throttle blade. this position goes back to pre-emission days.

Timed. The distributors aren't set up for constant vacuum.

Exactly gents. Thanks.

However, if your not running a stock type of distributor??????

I run stock style distributors and follow what the factory did, stock port, never a problem.

 

[Hilljack68]

However, if your not running a stock type of distributor??????

Thanks for all the feedback. Most of what I was reading on various other sites seemed to lean heavily toward using the timed port... but I couldn't seem to find any info on whether or not an electronic distributor made any difference.

 

[BSB67]

.......this position goes back to pre-emission days.

You are trying to start trouble

 

[rumblefish360]

Thanks for all the feedback. Most of what I was reading on various other sites seemed to lean heavily toward using the timed port... but I couldn't seem to find any info on whether or not an electronic distributor made any difference.

No, it really doesn’t. Other makes used full time vacuum. The type of distributor doesn’t matter.

 

[strokie]

I have a '71 340 with a Mopar electronic distributor and an Edelbrock 1411 750cfm carb. I'm hooking up the vacuum advance, but I'm not sure if I should hook into the "timed" or the "manifold" vacuum port. Any ideas? Thanks guys.



View attachment 741877

I have a 1967 Dodge Charger 451 cid, I use "manifold" vacuum port.
https://www.hemmings.com/users/654182/video/3842.html

 

[moobster]

If everything is stock, use the ported vacuum.
Manifold vacuum is used primarily for a performance engine with an upgraded camshaft but requires a re-curved distributor.

 

[lewtot184]

You are trying to start trouble

I know. can't stay out of it.

 

[Hilljack68]

If everything is stock, use the ported vacuum.
Manifold vacuum is used primarily for a performance engine with an upgraded camshaft but requires a re-curved distributor.

Well, it does have a slightly upgraded cam. Just a step above stock.

 

[rumblefish360]

Us the ported hook up then.

 

[lewtot184]

the vacuum advances are adjustable. use a 3/32" allen wrench in the nipple to adjust. clockwise brings the advance in sooner, counterclockwise delays advance.