I don't know anything about carbs at all, all I know is my car is idling way too high, and I can't close the manual choke more than halfway. I understand the choke lever may need adjusting, and need to at least go over my Q-jet. So, I have been searching for stuff online about them, and this page has a Quadrajet Decoder!!!! http://www.carburetion.com/quadnumber.htm There are other pages on the site that are great too, like this one: http://www.carburetion.com/carbinf.htm A few questions: I have decoded my Q-Jet to be some (likely-I must have written the number down wrong) 1975 Pontiac application Q-Jet, with (most likely) an electronic choke. I am pretty sure that my 63 nailhead doesn't really accomodate the electronic portion of the Q-Jet. But what do I know? So, I think the electronic choke isn't likely working-can I go without worrying about it? What can I do to make it work with the Nailhead? Should I get a more appropriate Q-Jet for the Nailhead? It's a 63 401 JT-code 325 HP engine. Actually, an ideal situation would be, since I don't have the correct engine for my car, I would trade the engine and carb for a proper 65-66 425 nailhead and Q-jet that fits, to, ideally, someone who is looking for the correct vin-numbered 401 Nailhead for their car. I can provide the vin if you are seriously interested. :Brow: Anyone looking for a their original 63 JT-code 401? I may have it :laugh: ANY help is very much appreciated. Christopher
I dunno... I'm not so sure they break them all down quite right. o No: I see a few probems with their method that does not work for 71-72 Buicks, so I don't trust the site. :Brow:
It doesn't work for a 7040246 ('70 stage1 carb) which was used for both TH400s and manual transmissions (Saginaw and Muncie). I'm sure there are probably more exceptions. Still, it's good enough to give you a rough idea of what you're looking at. Thanks Christopher!
Either way, it is a 75 carb, based on the number in the other post. How does your 63 engine have a manifold that accepts a Q-jet? The only nailheads with Q-jets were in 66, and the manifolds are pretty rare. The 66 Q-jet carbs are even rarer. Assuming that there is a 66 Q-jet intake on your car (and not an adapter plate), a 68-74 carb would work well with little adapation, if you can't find/afford a 66 Q-jet. If there is an adapter plate, ditch it and get an original Carter AFB or a new AFB/Edelbrock Performer carb.
I am not sure, but it looks like the intake is what came with the engine. It's painted red, and seems about the same age. I would have to get under the carb to know for sure. So, if the intake is a 66 the 68-74 Q-Jets would work OK? I will look up the numbers on the manifold tomorrow. WHat about keeping the '75 electric choke Q-Jet? Would this never work right? Any way to adapt it to suit my nailhead?
Quadrajet Nothing wrong with a Quadrajet. An excellent carb. Have it rebuilt properly by a pro, make sure the throttle shaft/plate isn't worn, etc.
Here's the deal. The original 66 Q-jet had the fuel inlet facing sideways, whereas the 68-74 has the fuel inlet pointing straight forward. The 66 used a hot air choke, whereas the 68-74 use a divorced choke in the manifold, so you will have to be creative to set up a choke (if you really want one.) I believe that your intake has a little heat crossover trough under the front of the carb. A 68-69 carb will cover it, but I don't think a 70-74 will. You will have to fill it with epoxy, or you will have an exhaust leak. It also may interfere with the fast idle linkage on a 70-74 carb. So, in summation, a 68-69 carb is going to be your best bet. 70-74 may require a spacer to clear all the linkage.
I hate to say it, but you could just use a Chevy Q-jet (which has the sideways inlet), and I believe they didn't go to a divorced choke until 1969..plus they're easier to find?
Fraid I can't argue with that suggestion. Or else the Edelbrock electric choke Q-jet (now out of production, but you could hunt for a used one)
