OK, I have a problem with my car, and I may have to rebuild/replace my carb, as I think that may be the cause. The carb is wrong, so I would rather find another one and rebuild it, and have a closer match to what the car should have. I have a 401 JTcode nailhead engine, and the original intake. What years Quadrajets will work? Are there any that won't? Are the linkages from non-Buick Q-jets so much different that I should stay away? Is it simply figuring out hooking up linkages properly, maybe fabricating some linkage to make it work, and making sure the carb mates to the intake properly? Who has the proper gaskets/baseplates reaadily available? (That I could order online, preferably). I may sound like I know a bunch already, but I have never worked on any carb except a lawnmower engine! I am asking in this way because I am interested in getting a Buick 850 CFM carb, which is not for a 66 car or 63 engine. I have also heard from a good source (mainly the great people on this board :TU: ) that a nailhead likes a high-flowing carb. Also, a classic-car resto shop told me to go to Lee auto parts to get a used (I guess remanufactured) carb-anyone with experience with Lee think they offer this? Thank you
Of, course, that would be ideal. I don't hold out hope that I would neccessarily have the luck to find the original setup though, and the cash. And I would like the 800 or 850 CFM Q-jet anyway. Would also expect to be able to get any old one relatively cheaply.
The only way you can use a Q-jet is to acquire a 66 Nailhead Q-jet intake. No other Nailhead intake will accept a Q-jet.
OK How different are the q-jet and, say the earlier quad rochester in terms of the way they mate to the intake? I would love to see the difference if someone can post the pictures of each from below.
Bill Stacy posted some pics of the various Nailhead intake options on his site: BuickStreet Forum :beer
Hi, Any Carter AFB, Rochester 4 Jet*, or Holley (with an adapter) can fit onto a stock (non-QJet Spreadbore) Nailhead intake. I dare say you could probably adapt a Q-Jet on there as well (using a holley-to-Q-Jet adapter upside down) but it'll take a bit of mucking around with a die grinder to make sure everything flows nicely (you could also use a set of hand files like I did before I bought my Dremmel - mmmmm dremel). I've tried all carbs on all intakes on my Nailhead except the old Rochester 4 jet (and the Quadrajet + adapter onto the stock carter intake - I used a Q-Jet intake for the Q-Jet but it will fit with an adapter + dremmel). I have one but it needs rebuilding. I mostly use it for linkage arc measurements which leads me to my next point. You can use any carb that physically fits onto the intake to power your car. All that's involved is either modifying your linkage or building a new one (like I did from a piece of flat bar with a hole on either end). My first new carb was an 1974 800 cfm Q-Jet from a Big block Pontiac Station Wagon. The linkages didn't line up so I spent a few hours with a vice, hacksaw, set of files and a drill. I was smoking tyres within a few hours. The fuel inlet didn't line up like old but so what? I just brought a new length of fuel line and made it fit. The kickdown and switch pitch plunger was a bit of hassle so I just removed it and brought a switch inside the car were I can choose the stall speed I desire at the flick of a switch. If it doesn't fit, it doesn't mean it doesn't fit. It just means it doesn't fit...yet. I have tools and a desire to get my Buick back on the road asap. I'll make things fit and enjoy the process... Let me know if there is anything else I can share with you about Nailheads and carbs. By the way, when it comes to cfm, I've noticed that the Nailhead likes as much carb as you can give it for the lower rpms but not much happens after about 4500rpm so I guess CFM is wasted but I didn't feel anything but more power across the range. Of course, my fuel economy went out the window so I'd agree that the Nailhead doesn't need 1,000, 1250 or 1500 cfm...but it certainly doesn't mind and I don't drive my 19' Electra for economy. The car drives "good" (carb tuning aside) with any size carb I've placed on there, but I'm sure it'll run it's best or better with a correct size carb and excellent tuning if you are really after extracting the last bit of power. I only mention this because I was surprised to find how sensitive it WASN'T to different carb sizes. Small changes were noticed at differing rev ranges but on the whole the Nailhead just said "Give me fuel (gas, petrol...whatever), make it around 13:1 and I'll be happy." I love my Nailhead. * In my original post I called it a Quadrajet 4 jet instead of a Rochester 4 Jet - Thanks Nicholas Blue text is edited or new text
Oops! I corrected myself in the second paragraph but missed the one on the first line. Yes, I mean the Rochester 4 Jet. Too many fumes?
Bill, if that is the latest pic of your Nail, how is the crankcase vapors being vented??? I notice no breathers in the Offy covers. Also, with a stocker type '66 cam the engine will run "out of breath" at 4500 the reason no improvements can be felt.
Hi Tom. Having mechanical control over the four primaries is more than I need as the car rarely sees 4000 rpm any more. Let's be honest. In my case it's more about looks than zoom. However, the car is a vastly different and more responsive animal now that I (with your help and Hank's rear end) installed the 3.42 gears. Early indications also point to the smaller 500cfm carbs adding more bottom end again. The car feels noticeably more powerful everywhere at every speed for several reasons but my goals are being met one way or another. Bigger, more power, louder...better. By the way. I sneak the crankcase vapors into the PCV inlet at the front of the front carb. See that rubber hose disappearing back under the manifold? I've drilled a hole in the valley cover and added a grommet and a 90 degree PCV that vents to that hose underneath the intake. It all takes place out of sight. I think it's pretty neat so long as the valley is a good place to vent from. Fresh air is drawn in through the ventilated oil cap. Please let me know if you think I'm missing something but it all seems to have worked quite well so far.
Glad to see the 3.42 gears at work. :3gears: Good Luck :beer MrHank (if the're from the rear end you bought from me)
Yes Hank they are the one's from your Riv! Works perfectly. Now, you and Tom join the many people who ride along with me whenever I take her out for a spin. Haven't left a pair of blackies yet as I'm still working on sorting out the intake and carbs but I'm having a lot of fun. The rear end made a huge difference to the car. It must have been like adding another 50 cubic inches because the difference is felt all round in ever driving condition from take off to overtaking at high speed. More power everywhere. I think the 3.07's were holding it back. It seems to smile more with the 3.42's. Sorry to hijack your thread Christopher
