Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

What rods/jets needed to dial this in?

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EspriTA350:
I have a 72 Pontiac Firebird 350 with a 17056274 qjet on it from 1976. This carb has already had the idle air bypass mods done to it and is freshly rebuilt from everydayperformance. I'm soon putting in a cam and higher cr iron heads on the car and want to make sure I don't: (1) kill the motor running it too lean or too rich, (2) maintain and/or further improve it's daily driving manners. Currently it nets 16.5 mpg on the highway with the ac on, and a 2.73 rear end + the usual TH350.

Specs on cam are:
hydraulic roller
LSA: 114
valve lift int: .478, exh: .498
duration @ .050 int: 210, exh: 218


Specs on heads:
Pontiac #16 small valve (1.96 int, 1.66 exh) with pocket porting and multi angle valve job. Stock 1.50 rocker ratio. Slightly milled combustion chambers down from 75cc to 72cc.

Car also has dual exhaust and full length tri-y headers. I'm aiming for a compression ratio in the low 9's

What size rods and jets should I try to dial this combo in?

tayto:
ask the builder of your carb?

EspriTA350:
Edit: Realized I forgot to mention it also has a 4 barrel iron intake, which is gasket-matched and lightly ported to suit the heads and cam. If any other info is needed please ask.


--- Quote from: tayto on April 11, 2020, 08:16:20 PM ---ask the builder of your carb?

--- End quote ---
I prefer Cliff's experience, thanks.

Cliff Ruggles:
It would be best to ask the folks who built it.

When I build them here they are set-up exactly for the application starting with air bleeds, idle tubes, DCR's, jets, metering rods and PP spring.  I also use a high flow N/S assembly and small float set to custom specs.

The folks who did the build may have modified the carb in areas differently than I would have and used different rebuild components, float height, etc.   So it's best to ask them how to proceed........Cliff

EspriTA350:

--- Quote from: Cliff Ruggles on April 14, 2020, 03:02:04 AM ---It would be best to ask the folks who built it.

When I build them here they are set-up exactly for the application starting with air bleeds, idle tubes, DCR's, jets, metering rods and PP spring.  I also use a high flow N/S assembly and small float set to custom specs.

The folks who did the build may have modified the carb in areas differently than I would have and used different rebuild components, float height, etc.   So it's best to ask them how to proceed........Cliff

--- End quote ---

Ah I understand. I will go from there, then. Thank you.

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