Racing my 780 Vac sec
10-01-2003, 09:53 PM
#1
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Car: 1986 Z28
Engine: 355
Transmission: th400
Racing my 780 Vac sec
it's been an interesting trip with this... nearly 40 year old carb.. but it's handled itsefl very nicely.
It's a list 3130 780 vac sec holley with downlegger boosters. OE carb off a 65 impala.
it's now powered my Vortec headed. Z28 to an 11.960 @ 113.51
and cut a string of 1.6x 60ers.
I've still got a good deal of fine tuning... when launching on the stickies i'll probalby need the next size up pump cam, the dark green might have a bit of a bog to it now.. only did it once though so far.
other than that... it's doing very well. the secondaries open up just out of the hole it seems.
This old carb is doing me right... easy to work with. and is certainly pretty good for power. for the fellas with vac sec holleys... keep working with them once you get them close you'll know it.. just keep plugging away... don't think you magically have to get rid of it to run faster.
will i eventually get rid of this warhorse... yeah... even carbs get retirement. I probalby won't get rid of it till i'm way deeper into the 11's though and change transmissions.
It's a list 3130 780 vac sec holley with downlegger boosters. OE carb off a 65 impala.
it's now powered my Vortec headed. Z28 to an 11.960 @ 113.51
and cut a string of 1.6x 60ers.
I've still got a good deal of fine tuning... when launching on the stickies i'll probalby need the next size up pump cam, the dark green might have a bit of a bog to it now.. only did it once though so far.
other than that... it's doing very well. the secondaries open up just out of the hole it seems.
This old carb is doing me right... easy to work with. and is certainly pretty good for power. for the fellas with vac sec holleys... keep working with them once you get them close you'll know it.. just keep plugging away... don't think you magically have to get rid of it to run faster.
will i eventually get rid of this warhorse... yeah... even carbs get retirement. I probalby won't get rid of it till i'm way deeper into the 11's though and change transmissions.
10-02-2003, 04:08 AM
#2
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Well I wouldn't be in a hurry to get rid of it.
Your's is a OEM carb with downleg boosters which are better than the straight leg boosters used on the "aftermarket" versions.
The metering block calibration is a little nicer.
Put it side by side with a modern aftermarket holley and compare
The choke horn is probabily also shorter than a aftermarket version. Makeing it work properly with drop base air cleaners.
I have a simular 715cfm vac sec holley OEM on 427ci Fords.
Like you, I've had this thing forever. it's always worked better than the late 3310's and runs the same or better quarter miles than double pumpers.
Just keep moveing it from motor to motor and car to car.
NHRA Stock Eliminators have to use the origional carb.
Some run well into the 10's with these carbs.
Asd you well know all you need to do is "jack it up and put real motor under it" to make it work.
Your's is a OEM carb with downleg boosters which are better than the straight leg boosters used on the "aftermarket" versions.
The metering block calibration is a little nicer.
Put it side by side with a modern aftermarket holley and compare
The choke horn is probabily also shorter than a aftermarket version. Makeing it work properly with drop base air cleaners.
I have a simular 715cfm vac sec holley OEM on 427ci Fords.
Like you, I've had this thing forever. it's always worked better than the late 3310's and runs the same or better quarter miles than double pumpers.
Just keep moveing it from motor to motor and car to car.
NHRA Stock Eliminators have to use the origional carb.
Some run well into the 10's with these carbs.
Asd you well know all you need to do is "jack it up and put real motor under it" to make it work.
10-04-2003, 09:35 AM
#3
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Car: 1986 Z28
Engine: 355
Transmission: th400
yeah this lil carb's a warrior.. i'll be keeping it for a long time most likely.. even if it's not on this car..
funny you mentioned bout the airhorn being shorter.. it certainly is by at least a lil bit of a margin.
when i race it though the air cleaner and stuff come off... and the hose between the bowls appears.
I definitly need that when luanching on anything but the street tires.. otherwise the sumbtich just cuts out.
funny you mentioned bout the airhorn being shorter.. it certainly is by at least a lil bit of a margin.
when i race it though the air cleaner and stuff come off... and the hose between the bowls appears.
I definitly need that when luanching on anything but the street tires.. otherwise the sumbtich just cuts out.
10-04-2003, 10:40 AM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
If you've got the traction to support it, a DP would probably produce quicker 60' & ET. But, the VS may just be what's letting your tires bite.
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