Carb guys, some help please
Thread Starter
Drifting
Joined: Mar 2001
Posts: 1,514
Likes: 1
Carb guys, some help please
Hey Folks,
I'm going from a stock 2-1-2 exhaust with a gutted cat to Hooker side pipes and JCL's tubes and baffles. Will I need to jet the quadrajet any?
Specs on carb:
17059230 1958 BYS (yes a caddy carb from '79)
has electric choke housing and vacuum lines from carb top thru intake back into choke housing.
Main rods marked 54P measure .026 tip to .054, taper length about .400
Main Jets #74's
Secondary rod marked DG tip measured .034, taper legth about .635
Secondary hanger #33797
The car has always run hotter at freeway speeds, but accleration is good no bog especially after putting in Larss' recurve kit.
Thanks for any input.
Scott
had to edit number snafu
[Modified by Scott78, 9:10 PM 3/13/2002]
[Modified by Scott78, 12:24 AM 3/14/2002]
I'm going from a stock 2-1-2 exhaust with a gutted cat to Hooker side pipes and JCL's tubes and baffles. Will I need to jet the quadrajet any?
Specs on carb:
17059230 1958 BYS (yes a caddy carb from '79)
has electric choke housing and vacuum lines from carb top thru intake back into choke housing.
Main rods marked 54P measure .026 tip to .054, taper length about .400
Main Jets #74's
Secondary rod marked DG tip measured .034, taper legth about .635
Secondary hanger #33797
The car has always run hotter at freeway speeds, but accleration is good no bog especially after putting in Larss' recurve kit.
Thanks for any input.
Scott
had to edit number snafu
[Modified by Scott78, 9:10 PM 3/13/2002]
[Modified by Scott78, 12:24 AM 3/14/2002]
Drifting
Joined: Nov 2000
Posts: 1,428
Likes: 0
Re: Carb guys, some help please (Scott78)
Believe the KEY word here is LARS.....hope he sees your post. He rebuilt my Q-Jet this past winter with super results......had a stumbling problem, but no more.......Good Luck :seeya
Thread Starter
Drifting
Joined: Mar 2001
Posts: 1,514
Likes: 1
Re: Carb guys, some help please (tnt76vette)
Yep a lars question for sure. I did e-mail him. I'm still having problems finding a place to get parts if I want to change the rods, jets are a napa item I guess
Scott
Scott
Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Carb guys, some help please (Scott78)
Scott -
Your carb is a 1979 Cadillac DeVille 425 Federal emissions with A/C and Auto Trans. The stock jetting is just as you describe: primary jets 74, primary rods 54, and secondary rods "DG." These rods have .0340" diameter power tips on them - very rich.
The 74/54 jetting combo is too lean at cruise and at WOT for your Vette, and this will give you an overheating problem. Since primary metering rods with the .026" power tips are tough to find, I suggest you keep the rods you have and step up to jet size #77. Set your float level to .425" with this jetting combo, and make sure your secondary airvalve is wound up to 3/4 turn on the spring screw. The "DG" secondary rods are exceptionally rich - you will probably pick up performance by leaning out the secondary side just a tad with a set of "DA" or "CH" rods. Both of these rods are available. Part numbers and specs are as follows:
DA 7046010 .0443" tip
CH 7045779 .0570" tip
A setup like this should run very well with your combination.
Contact me if you have any questions.
Your carb is a 1979 Cadillac DeVille 425 Federal emissions with A/C and Auto Trans. The stock jetting is just as you describe: primary jets 74, primary rods 54, and secondary rods "DG." These rods have .0340" diameter power tips on them - very rich.
The 74/54 jetting combo is too lean at cruise and at WOT for your Vette, and this will give you an overheating problem. Since primary metering rods with the .026" power tips are tough to find, I suggest you keep the rods you have and step up to jet size #77. Set your float level to .425" with this jetting combo, and make sure your secondary airvalve is wound up to 3/4 turn on the spring screw. The "DG" secondary rods are exceptionally rich - you will probably pick up performance by leaning out the secondary side just a tad with a set of "DA" or "CH" rods. Both of these rods are available. Part numbers and specs are as follows:
DA 7046010 .0443" tip
CH 7045779 .0570" tip
A setup like this should run very well with your combination.
Contact me if you have any questions.
