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Discussion Starter · #1 ·
To time...or to full vacuum that is the question. Alas poor Yourick, I...I wonder if he owned a Chevelle?
This is an exerpt from my Edelbrock owners manual for my #1405 (600cfm): Includes both timed and full vacuum ports for ignition advance.
I have a 70 with a stock 307 with an Edelbrock #2101 Performer intake. Which port should I use?
Thanks for any help, and you'll have to excuse the beginning it's only 6am here.
Fred

[This message has been edited by Riffers70 (edited 04-13-99).]
 

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try them both, usually port vacuum gives you the best idle and runs cooler. the factories ran full vacuum until emmisions became an issue. if you have to pass a sniffer test swap to the timed port.
 

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Discussion Starter · #4 ·
Thanks for the replies,
John, I'll take some time this weekend and try that.
Mark, both ports are located at the base of the carb in the front. One on either side of the PCV connection.
Fred
 

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Discussion Starter · #6 ·
Fred,
I haven't a CLUE! What I do know is this: I have been running it with the port on the right of the PCV with some minor problems during warmup. I switched to the one on the left this morning. I'll not try that again. She idled fine but coughed, sputtered and stalled, not to mention backfired thru the carb. sheesh! I am convinced that the carb is too big for the engine. I'm seriously thinking about going with teh Carter AFB 500cfm w/electrick choke.
Thanks for the replies!
Fred
 

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I have a 1407. The port to the right of the PCV valve is the full vacuum ("non-emission")port. I've used this with no problem.
To the left is the "timed" port.
Phil

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Fred and others
A "timed" or ported vacuum connection goes into the primary throttle bore just above the throttle plate so that it "sees" no vacuum when the throttle is closed but is "exposed" to vacuum when the throttle is opened. As I recall, ported vacuum was frequently used to extend the "time to boil at idle" primarily on air conditioned cars. If you have an idle overheating problem as in parades, curiseing, etc., I'd try "ported vacuum advance". On emission controlled vehicles, ported vacuum is used for a number of other functions like carbon cannister purge control.

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Fred Aldrich
Web Site: www.GeoCities.com/~69_chevelle
 

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Discussion Starter · #9 ·
Great...thanks for all the info!! At least I know what I'm looking at now...


And Al...if you come across this post and read it...one word....

THANKS!!!

This place is great!
 
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