General Category > Quadrajet Carb Talk and Tips
Divorced choke and headers
Cliff Ruggles:
Before folks using headers "successfully" get their panties all wadded up understand that I fully realize that there have been tremendous advances in header flange gasket/collector materials, coatings, wraps, much better heat resistant spark plug wires and mini-starters that aren't a big heat-sink are commonplace in the hobby. I use ALL of those those items here on "max-effort" vehicles, weekend warriors, and strong running street/strip vehicles. I also realize that there are also MAJOR differences between brands of headers, which include much thicker flanges that resist warping with greatly improved clamping force on the gaskets, and construction to make bolt access easier and greater clearance for plug wires/boots, etc.....plus many are available already "coated" (highly recommended).
However, for mild set-ups, daily drivers and anything that will see a LOT of street use, especially long highway cruising headers are not on the list of "upgrades" here........FWIW.......
bob69:
77cruiser, thanks for the web site link. I checked out the electric choke and its just what I was looking for. The electric choke bolts on in the same location as the divorced choke and hooks up to the q-jets stock choke linkage. It will allow me to keep the q-jet unmodified.
It does looks a little fragile and wonder how well it will hold up. Has anyone had experience with this electric choke?
bob69:
Cliff, I'm working on a 1969 Chevelle vert I bought in 2008. It had a 307, power glide, performer intake, headers and a holley with an electric choke. It ran very good. No issues with cold starts. Its a summertime "drive through the coastal mountains on weekends" driver. The glide started acting up and was swapped out for a 700r4.
The 307 was just not up to the task of driving up and down the mountains. It was constantly down shifting on every climb. Vey annoying. I wanted an engine that could cruise at 1500 rpm (about 35 mph) without having to down shift on the climbs.
I settled on a 400 sbc, builted to be a low speed torque engine. It has stock 441 heads, mild cam, perfomer RPM, headers and a 7029207 q-jet. The crossover is functional and has the thicker carb gasket. The rpm intake uses the 1970 style divorced choke.
The choke did stay on longer than normal but as a summertime driver it was not an issue. That 400 sbc did exactly what I wanted. Low speed cruising without having to down shift on climbs. More time enjoying the drive with the top down and little time working the gas pedal to maintain speed.
Winter driving was a whole different situation. Every couple months the car was driven to circulate the fluids and dry out any accumulated moisture. The choke would stay on waaaay too long.
For example, I picked up the car from storage, drove 5 mile on the freeway, drove back to my house on surface streets, pulled in the driveway and the choke was still on! I can't explain it, but that's what happens during the winter.
I ended up changing the q-jet with a hot air choke model converted to electric. Problem solved! The engine starts and runs beautifully when cold. Choke goes off in about two minutes and runs great.
The engine really does not need the crossover to run well (not in calif) when cold. Just needs choke control for initial start up.
To the member with the 396 comment, I also have a 1969 Nova with a 396, headers and q-jet. If you know the car this is a very big engine in a small engine bay. Everything is very close and tight. The divorced choke is not a problem. Air flow around the engine is limited and the choke/engine heats up relatively quickly.
Cliff Ruggles:
I should note here that divorced chokes are fully adjustable and IF you use a thicker than stock gasket the rod becomes too short and it will stay on a LOT longer.
The time from open to close is set by changing the length of the rod running up to the carb (there is some range of adjustment bending the stock rod one way or the other). I'd certainly play with that before spending any money to "convert" to a divorced electric choke or a different carburetor.
I'd also add that unless you were the last one to install the intake I'd make damn sure "restrictors" weren't installed to keep some heat out of the intake.
The 400 SBC is an excellent engine, too bad they didn't make them in greater quantities, you rarely see any of them for sale these days......
old cars:
where did I get lost here.
"I would like to keep the original 7029202 DH,"
"I'm working on a 1969 Chevelle"
"I ended up changing the q-jet with a hot air choke model converted to electric."
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