Hey I'm new to the forum my dad just handed down his 85 chev silverado 2door 2wd long box to me and I know nothing about the truck. I am fairly good with mechanics so getting it running shouldn't be a big problem but the carburetor is missing so I was hoping that someone might have an idea of what I could use. Also wether or not I should go used or new. Thanks in advance.
Sticking with the Q-jet is probably the simplest and cheapest thing you can do. Either rebuild it (or have it rebuilt) or get a new one. In the alternative (and my preference) would be to get an aftermarket carb. I've have too many frustrating experiences with Holleys and I am partial to Edelbrock. Also need to keep in mind the emissions. The stock Q-jet will work with all the emissions, many after market carbs won't.
One con on the Q-jets: the idle mixture screws on many 1980s Q-jets are inaccessible for emissions reasons and you can't adjust the idle mixture. I had a 1984 K5 with a 350 and went through this, but that was in California and maybe that was just a California thing, I dunno. If you want to have it well tuned then be sure your carb has the screws accessible.
On the plus side Q-jets were made for the stock set up and can take the fuel pressure of the stock fuel pump. If you went with Edelbrock, for example, you would need an inline fuel pressure gauge and regulator because Edelbrock carbs like to have around 6psi, 6.5 max. The stock fuel pump puts out more pressure than that and will over fill the carb with fuel leading to air-fuel ratio issues, which leads to tuning issues until you correct the fuel pressure. The truck will be very drivable, but you won't be able to get the engine perfectly tuned, or as close to perfect as possible, until the pressure is regulated.
The Q-jet is a spread bore and will bolt right on to the stock intake manifold. Many after market carbs, including Edelbrock, are square bore and you will need to buy an adapter plate to bolt to the stock manifold. In the alternative you could spend more money on a mild aftermarket performance intake manifold with a square bore. Would also give you a little bit more power.
I run an Edelbrock #1906 AVS2 650 cfm carb on an otherwise stock 454 and it brought the tired old truck back to life. I don't miss the Q-jet at all. If you did choose an after market carb, for a 305 I would recommend the Edelbrock #1903 AVS2 500 cfm with electric choke or #1902 with a manual choke.
