I too have an Oldsmobile 455 I had the stock quadrajet with electric choke and my motor is built pretty good and the quadrajet wasn't enough I put a Holley 750 double Pumper mechanical secondaries and manual choke and it runs great I do like the quadrajet but I think the Holley is the best choice that's just my opinion ... is your motor stock or built
Just found this thread from a search and wonder why nobody answered with more info?
I would like to hear others opinion also being I have an edelbrock/webber on my olds. The choke is not wired up and it starts and runs fine.
I am changing over to chevy and today I found out I have an 800 cfm quadrajet. problem is it has the heat tube choke and I was thinking of changing over to electric. In the process I also have been thinking about my edelbrock and wondering if I need to run a choke or not?
How is everyone's carb hooked up? Choke, no choke?
Fire it up in the boat and see how it runs and then make a decision?
A Q- Jet has very small primaries and huge secondaries.It was designed for a car to maximize fuel economy and have all the power when you mash the throttle. A car works at part throttle alot of time and vacuum advance distributor and a Q Jet makes sense. A boat is under load all the time so that Q Jet has the secondaries open just to maintain a plane. Have someone watch the carb and when the secondaries open and you will verify this. The best carb for a 455 Olds with mild cam and compression is the Holley 3310 -750 CFM. It will do wonders for your fuel economy and improve power. Vac secondaries are probably your best bet. You can pickup a aluminum hi rise that takes the carb on ebay cheap. Don't get an adapter and bolt it to the iron manifold
.......Q Jet has the secondaries open just to maintain a plane.
Not true. I turned a 9.25" impeller in a 22' day cruiser at 2900 RPM (30 mph) on just the primaries. The Q-jet is a good carburetor. Most people just don't understand how they work.
And to answer bentshaft: Under "normal" boating conditions (> 60 deg F), you don't need a choke if you have an electric fuel pump. Pump the gas 3 times prior to turning it over after turning the ignition on (this assumes that you don't have a low oil pressure fuel pump cut-off switch in the fuel pump circuit). Let it sit for 5 seconds. Then crank. If you have a mechanical pump and the fuel bowl leaks (common problem with Q-jets), it may take some cranking before the fuel bowl fills up, after which you can pump fuel into the carb from the accelerator pump(s).
Q jet, Holley, Carter, choke, no choke...... It's all about drive-ability. Under "normal" boating conditions, (temps that allow swim suits) a choke is not necessary. If you boat in adverse weather conditions, like fishing with the kids at daybreak, you might want a choke.... Most applications see no performance gain by removing the choke butterfly, yet it is not uncommon to see the entire choke horn removed... IMO, most recreational boats are so over carb'd, and butt fat, chokes are not necessary unless you're boating in Alaska....
Knowing some will argue about "fuel economy" or the sucess they had with a QJ on a door slammer, I will opine its (The QJ) the hands down worst carb for performance applications and I dont care for or uses Edelbrocks or Carters when given a choice, trust that I worked on and with these at Olds/Cadilac in the 70's and forward and do have some expirience having worked on and rebuilt hundreds , Holleys and Holley clones are by far the best choices IMO for most all marine and Hot rod applications , re the choke ,"divorce it" either by removing it altogether or defeating somehow and the fast idle cam , light the motor and keep it running with the foot feed till it get some "temp" on the engine to idle on its own Tom