I've got a dead-stock 401 in the Electra with about 3,000 miles since being totally rebuilt. It has new everything in it, and it has a Rochester Q-Jet and manifold on it. It's set to stock tune, and runs on 94 octane pump gas. I was expecting with a rebuilt driveline that there would actually some punch to this car. I don't expect it to perform like my old 430 Wildcat did, but I didn't expect it to be such a slouch either. As it was I could barely beat a brand new Toyota 1/2 ton from a rolling start. Here's the problem; - WOT doesn't seem to have that much more punch over part throttle. In fact, it seems the car is quicker on part throttle spurts than it is when the 4 bbls are totally opened up. The carb has been completely rebuilt to 66 spec, and the tranny is the original 400 but completely rebuilt including a new switch-pitch switch and torque converter. The only original part is the distributor, I couldn't get a new one. It looks like it's working fine, but who knows. So the car goes through and makes all the propper noises, tries to hook-up, and will only really start to pull at high RPM. Oh yeah, it does have a 3.07 posi in it as well. There are no vacuum leaks, there is plenty of compression, and even compression at 175 lbs, ignition is still breaker point, and the dwell is bang on what Buick suggests. No; - I'm not intending to race this thing out. All I'd like is a car that performs like it should from the factory. Any ideas, or are these cars just too heavy for the 401?
Are you sure your secondarys are opening all the way up? Another thing, is the heat riser valve working and if not, is it in the open position? Good fuel pressure, filter, pump? Just a few things I would start with. Also consider that those stock specs were intended to run on leaded fuel. You may want to adjust for timing to get more out of your motor with todays fuel. Check out Larrys thread on power timing if you havent already. http://www.v8buick.com/showthread.php?t=63475
I am just proud to hear someone with a nail raced and beat someone. Way to beat down that 1/2 ton pick up, and with a electra.ou: :beers2: I would also be looking at your carb for WOT problems.
I have a 66 as well. before it was mine it was my dads. the best he did in the quarter with that thing was 13.33 not this car has a bigger cam and is also bored 30 out of the original 401 and its not a posi car. im running a rochester 4gc with sunk floats and it will get up and go just fine.
A very common problem Ive found is that the gas pedal doesnt open the carb up 100% when you floor it. With the car off, have someone get in the car and press the pedal to the floor. When the pedal is floored, take a flashlight and look down the carb. All 4 throttle blades should be vertical. I found that most cars need adjustment. The adjustment could be on the carb or the linkage could havea turnbuckle. With my old GS-350, I couldnt understand why the car felt so slow even after a messing with everything. Turns out the pedal was only opening the carb 3/4 of the way. Once I fixed that, it felt like a different car. Something easy to check too.
Keep in mind the new Toyota pick ups if they have the 5.7 liter motor have 390 hp and 410 tq 4:30 rear gears and 6 speed transmissions. I have one and it moves right along so your tune may not be as far off as you fear.
Yep, what Jason says....sounds like your carb is not opening up.... ck the choke lock out... set the timing to 10 or 12 deg basic.... that 401 should have no trouble barking the tires... at least a little from a dead stop....look at my list of cheap tricks....:Brow: :laugh: :laugh: granted the wildkitty is a big heavy car, but it should be able to make black marks...
If your switch pitch is not kicking on, you're confined to turtle races. That 13 inch converter is TIGHT in low stall. It will never have spunk till its fixed. Also make certain that heat riser is open. I always removed them and hammered a soft bolt into the hole. Be sure there is NO exhaust restriction anywhere. Motor Trend tested two 4500 lb, 1964 Wildcats * The single 4 barrel 401 ran 16.4 sec at 83 mph * The super 2-4 barrel 425 ran 16.7 sec at 86 mph My god, those big 16 second boats were fun and fast. Most other big cars were more like 18.5 seconds in the 1/4 mi, or worse.
A properly tuned nailhead will run on low octane cheap gas. My 65 GS went to St. Louis International Raceway many times. I tried 110 octane on down to Thoney's cheapest. The 401 ran the same ET no matter what gas I bought. 14.60's with 90,000 virgin miles on it. The spark plug is in the center and nailheads were not detonation prone. NEVER HEARD ANY NAILHEAD KNOCK, EVER. They were absollutly wonderful engines!
X3 - those Tundas are pretty quick. I peg my car at being able to just break into the 14's and I think it hauls pretty good, especially considering what it is. Maybe your expectations were a little high?
My first thought was also the choke lock-out. It's on top of the secondary valve on the left side. Once it's warmed up, see if you can push the upper secondary valve open with your finger, or if the lock-out is still engaged. Can you HEAR the secondaries open? ...you should be able to, it's a cool sound!
Thanks for all the help guys, you've all given me some things to look at. The choke lock-out is working right; and the secondarys do open, but I'm not sure yet how much. I set up the linkage dimensions according to the service manual, but I didn't check to see if the gas pedal travel actually corresponds. All I did was try it from under the hood, where it all worked. One thing I have noticed since I changed off the AFB was that the car doesn't sound as "raw" as it did; it's actually quieter and more "refined" or muted. (Not sure if this makes any sense, I guess you'd have to listen to it) As I said, it seems to pick up better at higher revs; - then you can really hear the secondaries kick in. The carb was completely overhauled; new shafts, bushings, jets, and metering rods, and an updated needle and float set up to replace the original bad design. The carb was originally off of a 66 Wildcat with a 425 that was locked up since 1980. The carb had to be completely stripped apart since it too was frozen. There aren't any apparent vacuum leaks because the engine vacuum is a strong 20 in. with no needle bounce. When the throttle is "goosed", the vacuum gauge reads like it should. I tuned the car with a timing light first, and then maximized vacuum afterwards, so it should be near the "ping-point". I'll check and see what that actually worked out to with the light later. Since the harmonic balancer is still the original one I wasn't sure if it had shifted or anything, it looked pretty good to start with. The only thing that's funny about this carb is the vacuum dash-pot on the passenger's side; - on later versions this is the dampener for the secondaries, and this early version it looks like it has more to do with the choke. It works, just how well I don't have any real way of telling; there's no vacuum port to hook up to as it's integral to the carb body. The kickdown and switch pitch switch is working; - here again, I set it all up to factory dimensions. What I'd like to know is how to set the actual switch itself, is it supposed to come on and put power through the moment the throttle is moved, or is there a "dead space" where nothing happens until the throttle is at a certain point? The service manual wasn't very clear about this. Right now power comes on to the switch the moment the throttle is deflected. I was very surprised to see just how fast a modern Toyota pick-up could be; - those things really move. This one did have the big V-8 in it. I was alongside him long enought to read the trim. It's pretty tough to get any tire-spin off of my car, WOT doesn't seem to do it unless you're going around a corner. Then the car gets absolutely stupid. The Toyota and I were pretty much neck and neck from the start; he got a bit of a jump over me off the line. However, above 80 mph the Buick came into it's own, and then started to pull away. I found this same thing in the mountains too; there was no way that a modern unit could out-accelerate that Buick going up-hill, particularly above 70 mph. Hell, maybe I don't have anything to worry about; - but I'll check those things that were suggested and report back if there's any improvement.
Yes, that's the vacuum break for the choke. It makes the choke open when vacuum is applied. The secondary valve dampener is a plunger assembly located in the carb body. Unique to the early Q-jets. Later carbs used a vacuum diaphram. Secondary opening RATE is controlled by both airflow and the spring tension at the end of the sec shaft. You could lessen that spring tension to make the secondaries kick in sooner. Go too far and it'll bog.
yeah all these newer trucks run really well gotta think they have double the gearing of the buick. my 01 chevy would run mid 15s stock. my diesel with a tune runs 13s.
untill you let off of it some.... The way the factory set it up there are 2 switches one to make the high stall come on at idle and one to make the stall come on at or near WOT.... in between that for normal driving the low stall is in to get gas mileage.... I had my car set up on a dash toggle switch to make it stay on all the time when i was racing.... with a 4.11 posi and high stall the car was a beast out of the hole, then super strong in 2nd and pulled like a freight train in high.... and of course you had 2 reverse speeds ,,,,,:laugh: :laugh:
Thanks again Doc - I've just starting to figure out how to override this thing, make it work from a 1/4 mile perspective. You got your best times out of keeping it in high stall allthe way through? My apologies for hijacking the thread... Rhett
