AVS2 800 carbs
From Edelbrock 1407 - Speed Talk
Tuner posted "The 1407 750 CFM uses the same casting for the primary cluster as the 625 CFM carbs in spite of the fact the venturi minor diameter is 5/16” or so lower in the 750 body. This places the exit of the booster venturi that much above the “vena contracta” in the air flow, the result is the “booster signal” is not obtained in the correct location and the metering is erratic, the A/F wanders rich and lean as load and RPM vary as the throttle position is changed."
In a post on RFS he mentions a fix: "I made some sleeves out of thin-wall brass tubing that fit over the booster and extended the length down to the vena contracta and with that it worked like a normal carb by inserting a tube sleeve to extend the booster to the proper depth."
There are also variations in the cluster pickup tubes. @Hysteric posted this image on page 3 of the speedtalk thread.
Reposting the photo here because I'm not sure you can sign up for speedtalk at this time.
1. Eddie 750 (1407) 2. Carter 625 3. Eddie 800AVS
Brief history of the long boosters and their disapperance:
After the company was flipped through a few corporate configurations and Sealed Power - Federal Mogul took over the production, and subsequently the carbs morphed in to the “Weber” Edelbrock versions we see for the last 20 years, the longer booster production stopped and the large venturi ‘750 castings had to use the same high short booster as the smaller ‘625’ carbs.
Needless to say, the 750s with short boosters that don’t reach the vena contracta haven’t been a good carb in all throttle positions and RPM ranges.
Seems like its the parts Edelbrock usually puts in them.
From Edelbrock 1407 - Speed Talk
Tuner posted "The 1407 750 CFM uses the same casting for the primary cluster as the 625 CFM carbs in spite of the fact the venturi minor diameter is 5/16” or so lower in the 750 body. This places the exit of the booster venturi that much above the “vena contracta” in the air flow, the result is the “booster signal” is not obtained in the correct location and the metering is erratic, the A/F wanders rich and lean as load and RPM vary as the throttle position is changed."
In a post on RFS he mentions a fix: "I made some sleeves out of thin-wall brass tubing that fit over the booster and extended the length down to the vena contracta and with that it worked like a normal carb by inserting a tube sleeve to extend the booster to the proper depth."
There are also variations in the cluster pickup tubes. @Hysteric posted this image on page 3 of the speedtalk thread.
Reposting the photo here because I'm not sure you can sign up for speedtalk at this time.
1. Eddie 750 (1407) 2. Carter 625 3. Eddie 800AVS
Brief history of the long boosters and their disapperance:
After the company was flipped through a few corporate configurations and Sealed Power - Federal Mogul took over the production, and subsequently the carbs morphed in to the “Weber” Edelbrock versions we see for the last 20 years, the longer booster production stopped and the large venturi ‘750 castings had to use the same high short booster as the smaller ‘625’ carbs.
Needless to say, the 750s with short boosters that don’t reach the vena contracta haven’t been a good carb in all throttle positions and RPM ranges.