Get rid of the '66 Carb, use at the minimum the late '67 carb numbers ending 248, even if they "updated the needle and seat" to the newer kind, it will never flow enough fuel to keep up.. Holes just to small in the seat..
So in my ultimate stupidity I decided to go for a drive with the car today. It ended up coming home on a tow truck. The fuel pump had disintegrated. When I took it off, it fell apart in my hand. So much for fuel pump #3. The lever (handle, whatever) was twisted and crushed, and it busted off the housing. It was a veritable pretzel. See the picture below. I'm not going to begin to speculate what happened there. I'm just lucky it held together long enough and well enough for me to get all the shrapnel out. So Tom's fuel pump goes on, and lo and behold, it has pressure. So much so that there's gas spewing out the accelerator pump and over the float so it's bubbling up out the vents and the overflows. That's it, that !@#$%^&!! Q-jet has to come off. I find and haul out the old Carter and manifold, load it on, and yes, the car runs. Surprising thing is that it doesn't leak, even after being off for 5 years or so. (The Q-Jet only had a total of about 1500 miles on it; it never really ran well enough for me to totally trust the car.) So tomorrow I'm going to re-tune the whole thing. I took the car around the block, and it is a lot peppier, but is still "off" at WOT and still needs some adjustment. It pings when loaded up, so it'll have to be backed off a bit. But it idles and runs again. It still has a miss, but no stumble. It doesn't vibrate or rock half as bad as it did. As for the Q-Jet, I might take it apart and see what went wrong. Right now I don't want to look at it. Chances are it is now for sale, complete with manifold and powder-coated air-cleaner. I've had it with that thing. If I toss a kit into it, it would only be to sell it, I'm not putting it on the car again. I paid a lot of money out to have "it done right" only to find it's still junk, although now very pretty junk. I'm not going to try and make that POS work; I'll leave it to a Rochester expert or someone with lots of spares who can mix and match the proper parts. I'm a good carb rebuilder, but that one was a total wreck when I got it, so I didn't do the work to it. I took it to a professional carb rebuilder. Cost me $600, along with tanking the manifold. I'm not running races, and to tell the truth, I never really noticed a difference in power or driveability with the Q-Jet. It could be that it was a dog right from the word go. The AFB is adequate, and at least it's an easy rebuild. I've done thousands of them, so I'm not worried. So I'll report back and will hopefully conclude this saga tomorrow when I retune the motor.
If this is still for sale with upgraded viton internals and the choke plate removed, you'd be good to go.. http://www.v8buick.com/showthread.php?284432-NOS-7027248-Quadrajet
Wow, that is a repeat of the situation I had in 2008. 65 Wildcat, engine kinda doggy with carter, so I bolted on a customized 66 Q Jet and manifold. Ran better but not like the thing should with 3.42 gears . Drove it to the BCA in Flint and back without any problems. One day gas starts pouring out of top of carb, lucky no fire and I was close to my garage. I bailed on the q jet and put a rebuilt carter on it... Something was off in the engine, I sold the car and never figured it out.
So I tuned up the car today. Started with the dwell, it was 34 degrees, set it back to 30. Set the timing back, after I located the mark. Set it to the book value. Checked points profile, looked good. All Oscilloscope profiles are were as they should be. Checked coil input and output, adequate, but no great shakes. I'm thinking about converting both cars to a Pertronix or equivalent at some point coming up. Checked total advance, 22,3 degrees. Not bad, all readings stable. The timing light actually works, amazing when you actually press the right buttons. Should have read the instructions more carefully the first time. Cylinder balance indicates a bit lean, so the Carter got tweaked as well. Vacuum reading 18 and a solid needle and is maximized at 550 RPM, so it should still be in the idle circuit, and not off-idle. So: dwell, 30 degrees, timing, 5 1/2 degrees BTDC, idle 550 RPM, vacuum 18 in/hg, pretty much textbook settings. Took it out for a drive; - ok, it's no tire shredder, but then again it's an Electra. Good low end pull, the chugging is gone. Reset switch-pitch and kick-down back to the old marks, and now it's downshifting and pulling nicely. 4 barrels are online, actually heard them engage. Car pulls positively throughout, no rattling, pinging or stumbling. It looks like I have it pretty close. It probably could do with a bit more advance on the initial timing, it's not going to win any races, but who cares. I'll see how the fuel economy goes before I fiddle with it some more. It now starts at the first crack of the key, and the choke pops in and the high idle engages, without smoke or soot, which the other carb did a lot of. It still has a bit of a miss; - not as pronounced but sort of a pop, pop on idle. The motor doesn't shake rattle and roll anymore, it's actually pretty stable. Can't stand a glass of water on it for any length of time, but now at least a person can stand a glass of water on it whereas before it was pretty rocky. Performance wise, it sounds throatier, pulls harder, and is smooth. The Carter AFB is still the original one, and it has worn throttle shafts. It probably last had a kit thrown into it during the Reagan Administration, so it could probably use an overhaul. That was the reason why I changed it off in the first place. But, I was so hell-bent on making the Q-Jet work that I ignored the fact that it actually didn't run half bad to start with. So I think I got it...thanks for all the help and advice!
If it has a consistent "popping" noise in the intake, especially when winging the throttle, that can be an intake valve not seating properly. You describe the motor as still having a "miss" so that is a good possibility. I`m quite surprised having read thru all the posts on this thread that a compression/leakdown test was not a consistently recommended starting point. A thorough troubleshooting of any miss, stumble, chugging, low vacuum level or poor idle quality should ALWAYS start with a mechanical check of the engine...always. Especially on a simple `60`s vehicle which is soooo easily performed. Great to hear you have the beast running well enough again, thanks for sharing, Tom Mooney
You can detect an intake valve problem sometimes with a sensitive vacuum gauge. As you open the throttle a healthy amount by hand, while the vacuum is low it will flutter the needle before the revs catch up and the gauge reads higher again and smooths back out. If you are inclined to do so, the compression gauge hose can be used to chuck air into the cylinder (at TDC) to verify air leakage, after removing the schrader valve and adapting it for a quick connect nipple. Leaky intake valves are very common, even with fresh valve jobs.
You guys are right, which is why I put it on a vacuum gauge to see if there was a valve problem. It's a rock-steady needle, and it responds properly. Took the car out for a drive this evening and spanked it; - it performed better than it ever did with the Q-jet on it. The Q-jet is garbage. There is no hesitation anymore. It just goes. Now that I have the switch-pitch set up better, it doesn't lug, it revs up and pulls. Still needs a bit of tweaking though, it's not 100% yet. As I said previously, I know the AFB is due for a rebuild; -there is a very minor vacuum leak in and about the throttle shafts. Cylinder balance, vacuum profile look ok. I will do a compression test to it the next time I yank out the plugs, because I'd like to see how it's doing. I know one cam lobe experienced a little degradation in the form of scratches and scuffing when the rocker shaft blew apart just after it was built, so it may be that cylinder that's the issue. So yes, I will continue to try and source the miss. It's consistent enough to be a bad plug wire, or one that's arcing across, that was one thing I didn't replace yet. And, the coil is older than dirt.
Interesting...I paid a ton of money for a 3 angle grind and fit. The machinist supposedly hand lapped them too. But what you're saying makes sense too; - so I'll give it a try and see. I'll re-read my vacuum gauge diagnostics chart and give it a shot. Then I'll do a compression test.
yeah...I see those kinds of vj's every week. Nothing's perfect, (takes deep breath)... There are a few engine types that the seats will pull a little bit out when the head is bolted to a torque plate and valves sometimes need angle or TIR correction from fresh out of the pkg. (I haven't tried that on a Nailhead though) Lapping can easily obscure deviations by taking the highest point of contact and sweeping it around, possibly fooling someone into seeing what appears to be an even contact pattern or using too much paste, which makes it possible to impart into the mating surfaces. Even in the lightning pace of a production environment where you might do 50 heads a day, a quick 100% check can be a Mityvac hooked to a plastic (o-ringed) cover of sorts. Any that fail get a "bump" from a piloted stone. Truly the best visual method is ink, but even that is commonly applied too thickly to have merit, as it can glob from the valve to the seat. (I've seen Dykem Hi-Spot ink intentionally mis-applied in a CNC OEM application as "proof" of inspection when the part technically didn't pass spec but was to be assembled in house to the other mating part that had a 20 year history together of zero failures. Distortions from assembly pressures and techniques alter the fit of the parts better anyways in that case, lol .) Here's what was a perfect looking 3 angle exhaust seat (hardened insert). The right side of the seat shows all 3 angles completely obliterated by my stone, only initially used to show the contact pattern by cutting through the ink. The left side shows the untouched ink yet at that point. Ugh. One explanation might be that the seat wasn't driven in all the way, thereby shifting and fully seating into the counterbore as a result of the massive spring and high rpms using the valve to pound it in the rest of the way. :grin: The valve and guide were excessively worn. This might not show up on a vac gauge being exhaust, and probably not heard with the massive cam's rough idle and possible open headers. I've also personally seen the area's #2 placing B mod car's engine go several seasons before being installed into a 4x4 with a milder cam. 7 Int. and 7 Exh. seats were leaky but didn't show up until the carb was being "tuned" for the milder app., same reasons as the above example. All that potential havoc and shops still hear, "but I can get a valve job for $125 down the street". Hehe.
"Leaky intake valves are very common, even with fresh valve jobs"... and sticky valves from guide to valve clearance too tight (even when you supply the specs :Brow:)
Sticky valves can simply be from the valve bending as it seats on an out of round seat, as described as "excessive valve and guide wear" in my lengthy response above. That particular example wore the guide in the direction of the seat's deviation (side to side), not the typical "in line with the valvetrain's motion" pattern as so often seen.
I disagree, I say the one you have is now expensive garbage, good for a numbers matching show car and that's it.. They're dangerous to drive because when the updated needle and seat to bypass the plunger the cap pops, fuel overflows the top of the carb and can start a fire, and they don't flow enough fuel to keep the fuel bowl filled anyways with these big engines.. but luckily the late '67 7027248 quadrajet for your 430 mounts exactly the same as the '66 and has a lot of updates that work well enough, mainly the standard screw in needle and seat that we all know about now today.. you can adapt a newer model year qjet, by taking that throttle linkage end off the shaft you have now and swapping it to the donor carbs shaft.. beware also that, any newer than '67 carb bases aren't going to cover the U shaped exhaust passage under the carb and a bit of grinding on the edge of the manifold or spacer may be required for the choke linkages on the passengers side of carb if retaining them.. Pluses, The '67 carb already has the same base plate and throttle linkage as required for the nailhead, you already own a '67 car, so, once you get good at putting a kit one, then carbs the same on both cars making repairs and learning curve simpler... stay away from the early '67 carb as it has the same plunger style needle seat garbage only good to steal parts from numbers ending 240.. I'd keep the manifold, and find another core carb or even try the one off your 430 to test.. I'll bet you'll be impressed once you get the right combo on it.. Don't let that old engine beat you, you beat it !!!!!!!!!! This one should have the better pressed it plugs that typically leak in the early models plus all the updates to '74 - http://www.ebay.com/itm/ROCHESTER-QUADRAJET-CARBURETOR-7027248-1967-BUICK-WILDCAT-430-ENGINE-/201545848814
My very recent (as in today) research has more or less said the same thing, and I was starting to hunt down a late 67 Q-jet. I had a Carter manufactured one here somewhere, but I can't find it. Right now I'm going to run the AFB, and if I find another 67 carb, I'll use it. What you said about the modified needle and seat is exactly what happened. So I guess I'll polish up the 66 Q-jet and put it on the mantle as an expensive mistake. I've had great luck with the later Q-jets, so when this one turned out to be a dog it surprised me, I always thought a Q-jet to be bullet proof. Guess I know better now. As for the valves, wow...that is disconcerting...The heads have their original seats, being that they are so close to water I chose to leave them alone. However, each valve and guide was replaced, and not just knurled. I guess a compression test will prove it out.
Actually...a compression test won't always tell you that much. Chucking air into the cylinder and listening for it's escape will, not that I'm leaning you to that as the main cause.
Some more reading Lemmy-67 Q-Jet Quartet - http://www.v8buick.com/showthread.php?242604-Q-Jet-Quartet Since the Nailhead has no provision for a manifold mounted choke, Talking with Ken about using his Patent Pending Electric Choke Conversion Kit on the '67 carb, seems so far that it will work if the 3 teeth are removed from the rear of the oem choke mounting bracket.. I haven't been running a choke for some time and have removed the choke plate altogether in favor of a bit more primary airflow with no ill effects besides the initial few minutes of feathering the throttle, Just don't want to steer anyone in the wrong direction if a choke is needed or wanted for the nail.. Definitely gonna use one on my '74 800 cfm Buick 455 qjet that I adapted to my 390 ford f150.. http://www.ebay.com/itm/182020763411?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
