So the 401 is giving me grief again. First it refused to start. Poured a shot of gas in it, it took off. Then, transitioning from Park to drive, it quit, refused to start. Another shot of gas, and away we went. When it accelerates, it kinda goes "chug-chug-chug-chug", - not a clean easy pull. So I figured it was timing. Put it on a vacuum gauge, it was reading about 14, and that was at set point on the timing mark. So I ran it up to 18, and lost the mark. My timing light isn't worth a damn anyway. When the distributor vacuum advance was disconnected, the car ran lumpy, and at 18 it smoothed out. Put on the advance, and it's lumpy again, and has a miss. Dwell says it's about right; - 25-29 degrees. Took it for a test drive; - now it has a pre ignition knock when you label it hard. So it's close, a little too far advanced, but still, no tire shredding power, and it's lumpy with what seems to be a miss. The plugs, cap, and point are all new. The coil is older than dirt. The carb is a totally rebuilt 1966 Q-Jet from a 425 in a 66 Wildcat. So my questions; Does the vacuum advance on a nailhead run on spark ported or manifold vacuum? Mine is currently on manifold vacuum. It has a new fuel pump, but for some inexplicable reason it doesn't seem to hold a shot. This is fuel pump #3, is it NFG too? Or is it the accelerator pump in the carb? It stumbles coming off-idle and then once it catches, it pulls. 4 barrels are indistinct; - I've heard them once at high speed, but they don't seem to engage at lower RPM. What are the measurements for the stator rods? Is it possible the switch pitch isn't switching? All I did when I converted the carbs over was use the original AFB linkage and adjusted it to fit the Q-Jet. What are the signs of a shot distributor? So far it's the only part on that car that hasn't been replaced or rebuilt. Do I take the chance on some possibly sub-standard Asian made rebuild and order up a new one? So far I've been a little less than underwhelmed at the quality of modern jobber parts, it seems the original or NOS was better and with the rebuilt stuff it just isn't quite right, there's always something wrong with it. With one old Ford truck I had I went through 9 jobber carbs before I got one that would do what was expected. Each carb had some stupid little issue and wouldn't run right. This Buick is turning out to be the same way. I sent the Q-jet out to be totally re-manufactured, it came back to me all re-anodized and looking very pretty, a real piece of art. The guy told me he re-bushed it, added new shafts, modified the needle and seat to the newer kind, and checked over the cast. It sure looked like he did what he said. But that's about it. All I know at this point is that the worn out old Carter ran better than this POS is doing. I'm just about ready to dynamite this car. My other convertible has the original 430 in it and it runs like an absolute top, and still pulls huge power. I would expect that a recently rebuilt nailhead would walk all over a 130,000 mile original BBB, but no, the Nail is an absolute slouch and runs like a toilet.
Good grief-that all sounds like you're chasing your tail on this car. I'd start with the old 'rule' of 1st ensuring that your mechanicals are good(compression test) 2nd to verify your electrical and 3rd to deal with the fuel system. Yes-parts quality is often iffy and doesn't help. I've kept some 'known good spares' to help with troubleshooting. One of the guys sent out a carb at large expense as you'done and it came back and ran badly=the bowls had sand/beads in them from blasting for the 'beautification'. (I'll take mine plain, but functional thanks) good luck!
Marc - send me a box and a shipping label and I'll send you a "known good" Q-Jet to try out if you want, and then at least you can scratch that off the list. These cars can and will run, just as good as your 430.... You can use your vacuum gauge to measure fuel pressure, but remember pressure and volume are two different things. You've got something more fundamental going on, I'm with Lapham3 on this. And my personal mantra - "it's always ignition"
If you have to pour gas down the carburetor for it to fire, then the fuel bowl is empty. That could be a bad fuel pump, but I know Tommy sent you a new one. A new fuel pump won't work if there is a clog or restriction down stream, so that would be what I would check first. Inspect all the line from tank to carburetor. Look for old cranked rubber hose as well as pinched/twisted metal line. If the tank has never been dropped, do so and look at the pick up. It sounds more like a fuel problem to me. Checking the accelerator pump is easy. Look down the carburetor with the engine off. Briskly open the throttle and you should see 2 solid streams of fuel shoot into the 2 front barrels. If it is inadequate, that should be obvious. With an empty fuel bowl, that will be the case. As far as distributor points go, dwell is 30*. It should be set to 30*, not 25-29*. As you rev the engine, dwell should not vary very much, 1 maybe 2* at most, anymore than that, you have play in the shaft bushings, or bad point spring tension. Dwell affects timing, so if the dwell is wrong, so is the timing. Check and set the dwell first, then check timing. I have an entire thread dedicated to ignition timing. If you haven't read it, I recommend doing so. Everything is easily checked with a timing light, initial, mechanical, and vacuum advance can all be checked in minutes with any timing light. Remember, initial timing really means very little. What matters more is the total advance going down the road, and what you have with your foot to the floor. Again, easily checked with any timing light. There is no reason to guess. If you 401 is all stock, 14" of vacuum is low. Find out why. Good luck.
As for a shortage of fuel. Check the rubber line coming out of the tank 1st. If it is old it could have cracks in it that are sucking air but NOT leaking fuel. Then the rest of the fuel lines & hoses & lastly the sock in the tank. Any added fuel filters from previous owners???
X2 on what others have said about covering the basics. Check compression to be sure all is well internally. My 106k mile 401 has 135-165 PSI (avg is 152) when warm compression. Not the greatest but she runs OK and has decent power. Dwell should be 30*. I believe the vacuum advance should be connected to ported vacuum. I have my timing set to 2.5* BTDC with the vacuum line pulled and plugged. Idle is at ~800 RPM in "P" and 700 in "D". At these settings I get 18" vacuum. This is all with a Edelbrock 750 CFM carb. Check the pickup tube and sock filter in the tank. Mine was plugged solid with rust from inside the tank. I replaced all fuel lines and went through 3 fuel pumps before converting to electric after having the tank cut open, cleaned, and coated. Best of luck to you
If you have questions about your gas and want to verify it place a fuel line in a 5 gallon gas tank and connect it to your your fuel pump inlet. I do it quite frequently with older cars and it works like a charm! Most of the lines and tank are probably crusty by now and if you are not going to replace them you're asking for trouble. If it runs pouring fuel down the carb i'd bet it's the lines from the tank to the pump or the tank itself. Good luck with it and keep posting the people here are great and can help................ Rob
X2. With 2.5* initial timing, if you run ported vacuum to the advance canister, the engine would tend to run hot in stop and go traffic or while standing. Running manifold vacuum would boost the timing at idle 14-18*.
If the '64 has a vented (to the atmosphere) tank, I would be concerned about the sock on the pickup. These tanks will absorb moisture due to the Ethanol in the gasoline if the car hasn't been run regularly. Water equals rust. Rust equals a plugged sock.
The "shot" at startup is from the accel pump in the carb. While it is true low float bowl level can be responsible for no shot from the accel pump it sounds like you have enough fuel to run at off idle RPM and stumbles while at speed so I would suspect your accel pump is not operating correctly. When the engine is cold, before starting, hold choke plate open and look down the primary barrels as you bury the accel linkage. You should see a steady stream of fuel spraying out of the accel pump nozzles. If not, start the engine by manually priming, let it run for a few minutes, turn it off and do the same check again. Do you see a stream of fuel now? If not, chances are the accel pump is bad as after starting/running there should be enough fuel in the bowl to support the accel pump. You do have the choke adjusted so it closes completely when cold, correct? It sounds to me from your description of operation at different RPM`s that you have one or more engine misses. Start with a compression test and move on from there. Obviously and as stated a missing engine can also be due to ignition or fuel issues, but start at square 1 with a compression/leak down test. How old are the spark plugs? Have they recently been fuel fouled as in "flooded"? Has the car been moved in and out of the garage not coming up to operating temp for many cycles? Fuel fouled plugs will never be the same and are VERY often overlooked as a cause for poor overall performance, especially with older low voltage ignition systems If you do a cylinder power test by removing the spark plug wires one at a time to check if the cylinder is carrying power, and find a hole that is dead, try moving the wire away from the plug a little at a time until the spark is forced to jump a considerable gap. Be sure to insulate yourself. If the cylinder starts carrying power when you establish an extraordinary gap, creating a voltage spike and causing a lazy plug to start firing, then the plug is fouled. Good luck! Tom Mooney
A lot of good answers here, thanks! It looks like I'm going to have to go back to basics then. I didn't think I needed to because the engine has 5000 miles on from a total rebuild. All the pistons, rings, bearings, cam and valve train, timing set, etc was replaced. The only thing original to the original engine is the crank. The block even had to be replaced because the original was cracked. The rebuild is totally stock; - I'm anal about how I build engines, and I try to make them as God and the General intended them to be. I'll do a compression test. I really don't want to tear this thing down again but it's looking like I might have to. With new pistons, rings valves etc what would cause low compression? Thick gaskets? The re-pop gaskets I got in the kit were substantially thicker than the originals were. probably designed to take up warped heads, something that these ones were not, I had them milled. I'll check for a vacuum leak. Knowing my luck, the diaphragm on the secondary butterflies is probably NFG now, and of course it's not rebuildable, replaceable, and it can't be disconnected on these early Q-Jet casts. The cam was placed in properly, and the timing was done to the book. I didn't degree the cam, and it's supposedly a stock grind. The only part on that motor that was never replaced was the distributor. I can see I'm probably going to have to tear down the carb. I've already replaced the fuel line, eliminated the kinks, removed any extra filters, and ensured it's the correct size. The pump isn't the one that Tom sent me, it's a Rock Auto one that looks exactly the same. It seems to be putting out. The car is 10 times smoother and more drivable since that pump went on; -it'll do 100 mph now where it wouldn't before. I'll check the pressure and see if I can pull a volume without burning the car down. I want to keep Tom's pump on standby, but I'll use it if this one is weak. I'm also suspecting the accelerator pump. I took a look down the bores and wasn't too pleased with what I saw, (it looked weak) and it would account for the off-idle stumble. Since I changed the ignition, that has diminished. I'm thinking that some of the preignition or detonation I'm getting is because of a poor fuel shot. The car accelerates quite nicely at half throttle, falls on its face and pings at WOT. Basically with the vacuum settings, I remember reading years ago that one takes a point off the total for every 1000 feet above sea level he's at. We're at 2250 feet here, so that's -2 off the reading. So at 18 it's close, but at 145 it's definitely "off". I recently acquired an old Bear analyzer. It's a huge stand up tune up machine that's 6 feet tall and has an oscilloscope and everything built in it. It's the full-blown 1980s cream of the crop garage model. Lusted after one for years, now I've got it, and this is the one damn car that looks good on all the profiles yet still runs like crap. It's making me look like an idiot. It all still works, so I guess it's time to hook up the Buick and go through it all, again. I'm missing something fundamental and small here. I had the dwell at 29. The book said that was "preferred". However, if 30 is the proper number, I'll set it to that. There was a little deflection in the needle, but it always topped out at 29. I'll make sure the damn timing light is replaced. Last time I set it it was to 5 BTDC. I think that's what the book wanted. I seem to recall on older Nails that I ran that I could safely go to about 8-10 BTDC before it pinged. That also used to work out to about 18 on the vacuum gauge. As I said, I'll verify where the timing's at with a good light. How much advance should a stock distributor have? At what RPM range? Mercedes used to publish exactly what the advance was at "X" RPM, and put it on a curve so that it was easily decipherable. Dial it into the light, bring up the RPM, and voila! If the distributor worked, the line lined up to the mark, life was good. Haven't seen that for Buick. The plugs are an light ashy grey colour. No carbon or no oil fouling evident. I believe they're a set of Delco 44s in there now. Should be the correct heat range too. Fuel is 92 octane pump gas with no ethanol. (although some stations do use ethanol in their premium, which has been an issue with this car) Points and plugs, condenser and cap and rotor were done last fall. Last week I drove the car a couple hundred miles. It did well, but was no tire shredder. It used what I would consider a normal amount of fuel, about 1/2 a tank or so. I wasn't easy on the car, it was doing about 75-80 all the way. I'm not convinced that the tranny is completely right. It was completely rebuilt when I did the motor. It downshifts, but the Switch pitch seems to be off. Tough to fully discern in a convertible without a tach; the wind noise is usually more than the motor noise. I'll report back if I find anything...or there'll be a cheap Buick full of buckshot for sale in another section of this board. I've just about had it with this POS, it's not bloody rocket science yet this car absolutely refuses to work properly.
Marc, Before going any more crazy than you have already. Take a DEEP breath & stand back. Start AGAIN at the very beginning of basics & work yourself up. DON'T skip any BASIC steps. Go forward one step at a time during the troubleshooting/diagnostic process. MANY times there are ignition problems that appear to be fuel problems. So IGNITION is 1st. During this process use the KISS principal, KEEP IT SIMPLE STUPID. You'll be amazed what can be accomplished using this principal. It can & does solve alot of problems that aren't a MAJOR problem. Tom T.
Thanks for the correction, Tom. Oddly enough I have my advance connected correctly (manifold vacuum) but remembered incorrectly. Must be age creeping in.... Marc: I get 18" Hg at ~ 2900 feet elevation. The plugs should be a light tan to slightly gray, I believe. It sounds like you may be a little lean.
I agree with you all; - it has to be something simple. Right now I'm taking Tom's advice, I'm standing back. Probably get on it on the weekend again. A compression test before I start anything may not be a bad idea. See what I'm working with. Then, make sure that the primary timing is correct, by that I mean the right cylinder is firing when it should. TDC is where it should be, etc... Then, dwell, timing, and then play with the carb settings again. One thing I've had trouble with this carb right from the start was holding an idle at 550 RPM. It's set at 650-700, so it might be off-idle already. If I have to rip down the carb, I just might put the Carter back on. It ran pretty good, and I should have left things alone. But I'm beginning to suspect the carb isn't worth a tinker's cuss along with the distributor. The one thing that I haven't really checked out yet is the functionality of the coil. It's the original one too. If it's weak, that might be the stumble.
It gets posted a lot (for good reason), but many carbs are initially set up with too much throttle blade opening. Difficult to idle down and an off idle flat spot due to the unintentional use of the "off idle transfer slots" during idle, therefore no enrichment at tip-in and before main jet flow.
I too say step back and clear your mind. Start with the basics. But going with what you stated "First it refused to start. Poured a shot of gas in it, it took off. Then, transitioning from Park to drive, it quit, refused to start. Another shot of gas, and away we went. When it accelerates, it kinda goes "chug-chug-chug-chug", - not a clean easy pull." , IMO if your giving it gas to start and it is starving for gas when running then the delivery of gas is where i would start. Check fuel pressure and flow at the carb, if that is good go after the carb. Do you have another good carb to try on it?
Definitely not trying to push my previous post, but it also coincides well with woodchuck's post above. Certainly something basic is happening. Actually being there would shed tremendous light on things.
Not sure if you just said the magic words "I just might put the Carter back on. It ran pretty good, and I should have left things alone. But I'm beginning to suspect the carb isn't worth a tinker's cuss along with the distributor". Now dont take this the wrong way, but it ran ok before you touched it and now it dont, to fix it, undo what you touched, put it all back to how it was and it should go again Then, if you want to mess with things (which is what its all about, tinkering) change 1 thing at a time, that way, if you change something and it doesnt play the game, you know where to look. Basically, you have messed with 2 of the 3 basics an engine needs to run, leave the compression alone, get the ignition back, then mess with your fuel
