OK.. some of you are familiar with what I've done... but since it's a new thread I'll sum it up again... Mel's 71 Skylark (350-4V) started running real bad last week. Sounded VERY loaded up. I was going to give it a quick tune up. I changed the plugs (which were JET BLACK), cap and rotor. Fired it up for about 10 minutes and it started loading up again. I took out 2 plugs and they were just as black as the ones I just replaced. SO I thought it might be the carb. It was a small Holley 4 barrel vacuum secondaries. 600? 650? All I have laying around to drop on it to test my theory is an old greasy slimeball of a quadrajet off a "running" "junkyard 455" (future powerplant for my tubbed project) Anyways... I don't know anything about this carb, except that the engine supposedly ran before I bought it. Its a 1975 or 1976 engine. So I drop this quadrajet on it without even cleaning it up and "wire brushed" all the plugs. Amazingly it runs, and it actually runs not too bad. It may be a little on the rich side, but it definately has more power when you mash the pedal to the floor than the old Holley had. Unfortunately the idle is "inconsistant" to say the least. One minute it wants to die, the next it's idling at what sounds like about 1500. (no tach) So... I have a few questions, and I've attached a couple pictures. First questions relate to the vacuum hoses.... 1- Is there a "generic standard" I can go by for hooking up and/or plugging certain ports on the carb? 2- There's an extra vacuum hose coming out of the firewall that isn't hooked to anything. I can feel it pulling some vacuum, but there;s no place to hook it up that I can see. I also don't remember unhooking it when I removed the Holley. Anyways... in the pic below, you can see the ports on the front of the carb. I'll explain what each one is hooked to. Far left - The little hose just loops from one port on the carb to another. That piece was already on the carb. The next one goes back to a "tee" from the brake booster. The 3rd port on the "tee" goes to a PCV valve in the manifold. The one just to the right of the large one is plugged. The one on the far right goes to my distributor (Acell HEI)
Next picture is the back side (taken from the drivers side) OK.. hose on the far left goes from port to port on the carb. Again... this was already like that on the carb. Then theres 1 more port that I've plugged. I commend anyone who actually made it this far in my ramblings... and you deserve a reward just for that! :gt: But I would really appreciate any pointers or tips anyone might have to offer for me. :beer Oh.. by the way... I have the timing set at about 13 at idle, and "all in" it's around 26-27. This 350 has a small street cam in it. Does that sound reasonable?
The hose from the firewall should go to the back of your carb... I believe the port is on the throttle body (bottom plate of carb) EDIT: I just looked at your second pic: It is the vacuum fitting that is capped off in the rear that should connect to the firewall!! I have a carb just like that one that came off a 76 Buick 455. It also has the bottom center port plugged. I would think that whatever ports you are not using on the carb, you should plug to avoid vacuum leaks. But definitely get that firewall vacuum hose hooked up. I can post a pic of mine if you like...to at least point out the rear port.o No: I hate these smog carbs with 50 fittings on them:gt:
That would be great Adam! But I'm a little confused about something.... I can feel some vacuum in the hose coming from the firewall.... wouldn't it seem odd to hook a hose that's pulling vacuum into a port on the carb that going to pull vacuum against it? Seems like they would cancel each other out or something? But what do I know? Certainly nothing about quadrajets or 50 vacuum hoses. I'm used to 67's and Holleys! :gt: LOL
It's the way my 71 is...I'm assuming the qjets didn't change too much in that span of a few years. Try it and see....it may make the difference between laying rubber and not. When I left that vacuum hose off one time, I lost a TON of power. I was kind of embarassed...since it was right after I got the car and I was taking people for rides...and I tried to get on it... Blah.ou:
I'll give that a shot tomorrow morning. It'll only take a second to hook up. I'll drive it to work again tomorrow. It's getting close to "quiet time" now so I better not mess with it tonight. Our neighbors just love our Buicks... especially when I'm "tuning" at 10PM. LOL :gt:
Rick, first off that may be the dirtiest running carb I have ever seen. The idle is acting up because the 455 carb has idle air bypass valves in it that a 350 carb does not. This allows extra air into the engine causing fuel to drip into the carb. I have the same problem with my carb. Norm Dihl (Q-jet guru) looked mine over and told me that was the problem. Your timing sounds about right. Hook a vacumn guage up to adjust your mixture screws becuase it is probrably to rich for a 350.
LOL ... and that was after I "cleaned" it tonight. I bought a can of carb and choke cleaner and sprayed about 1/2 the can already. I was spraying inside and out to see if I could get it to idle better. You should have seen it BEFORE I cleaned it tonight. As I said in the first post... I was amazed it actually ran! :gt: Thanks for the tips, I'll get a gauge on it tomorrow. Is there any way to bypass the "idle air bypass valves" or disable them somehow?? Because I bet your right. The inconsistent idle does almost seem like it's getting gas "dripped" into it on and off. o No: Just for the record... I'm not exagerating one bit when I say that I know NOTHING about quadrajets. My only experience in the past with them, is replacing them with Holleys. But after reading all the "pro-quadrajet" comments here at V8Buick, I thought it was worth a shot. :beer
Just an update... The little hose on the firewall isn't near large enough to go on the port on the back of the carb Adam.
rick it may run to the vacumn ball (don't know the spacific name) mounted on the firewall for adjusting your interor heater controls.
Hi Phil There's already two connected to the "ball". There's a big one from the intake manifold, and a little one from the firewall. I don't see any other spots to hook up the 3rd hose. o No:
I will take a look tonight and see on my 70 GS. anyway you can send a photo to me also look to see if it is color codes (such as a yellow stripe on the side (it will help me reference the hose better) sent you a pm with email address to send the info to.
Rick, The rear nipple(larger hose) on the Q-jet should go to the vacuum tank on the firewall. The smaller hose goes into the firewall and is used to open and close doors in your heat/AC box. It also opens and closes the heater control valve(thats probably the one that is pulling vacuum) Try moving the temperature lever(heater controls) to one side and see if the vacuum stops. On the front of the carb, the large(3/8") nipple goes to the PCV valve. The other nipples should be ported and full vacuum. Run one of them to the distributor advance and individually plug all the nipples you don't use. There is no way around the fixed idle air bypass. It is meant to allow extra air for the big 455 idle. They run great on a 350 with a really hot cam. Good luck.
Thanks for the tips, I'll have to do some messing around... but now I have a NEW problem. (hopefully related?) The trans won't come out of first gear! The shifter is working properly, but the trans just won't shift to 2nd or 3rd. It also doesn't deccelerate (is that even a word?) the car. Like if I get on it and run it up to about 4,000 RPMS in first gear, as soon as I let off I should be able to feel the engine pulling the car down. But I don't. The engine immediately drops to idle and the car coasts like I popped it in neutral. Then if I give it gas, it feels like about a 3500 stall torque converter. I'm praying this has something to do with vacuum too?? I checked the fluid and it's only about a half pint low, so that shouldn't be it. ou:
Bad vacuum modulator? Check the fitting on the intake behind the carb going to the transmission. Replace the $10 vacuum modulator on the tranny. Probably the most cheap way of figuring it out.o No:
I agree with adam. Also check to see if there is fluid in the Vacumn line for the Vacumn modulator, It could pull tranny fluid to the carb.
I didn't have much time to tinker this weekend.... but I did crawl underneath and find that the short piece of rubber hose on the end of the steel line for the vacuum madulator had been against the header and melted a hole in it. *WHEW* (big sigh of relief) So I find another little piece of rubber hose and replace it..... Still no 2nd or 3rd gear. The whole ordeal took about 20 minutes.. and thats about all the time I had today. I didn't recheck the fluid. I'll do that tomorrow night. Since the hose had a hole in it.... could that have made the fluid read right on the dipstick even though it was low? Like maybe it needs the vacuum to suck the fluid up into the trans?? Sorry... I'm a transmission idiot. Oh yeah... I did stick a vacuum guage in the manifold too... it read around 15-16 at idle. I'm banking on just needing fluid. It was "wet" around the hose. It must have leaked some. o No:
Along the same topic, a buddy with a '71 Skylark 350-2 has been asking me about putting on a Holley 850 Dual Feed, on his STOCK block. I told him it's NOT "NECESSARY", he would only DROWN it with fuel, not performance. What would you recommend, to switch from a 2 to 4 bbl., as far as "how many cfm's" on a STOCK '71 Buick 350 engine?o No: Would anyone be willing to "trade" a "correct" 4 bbl. carb. for the 850 Holley?o No:
Geeze... where do I start... I'll try to keep it short, but I like to ramble. :gt: OK.. checked the tranny fluid again and it still said about a pint low. So I added pint, drove it around the block....checked it again... now it says full. Still no 2nd or 3rd gear. So I stuck a vacuum gauge on the hose going to the modulator.... it read 5. I stuck the gauge on the intake port that the modulater pipe went to... it said 15(ish) Ureeka! Must be a cracked tube or something. o No: So I pulled the steel tube completely out of the car where I could get to both ends easier... Hooked it up a few different ways and got 15 all the time. WTF? Looked closer and found that the rubber hose I used to replace the burned one fit kinda loose on the tube. Depending on how I pulled on the hose, I got anywhere from 0 to 15" of vacuum. So I used a different hose, put it all back together and now I have all 3 gears!! :TU: ou: So this got me to thinking about the weird idle.... I got my starting fluid out again, and sprayed some by the throttle shaft... It rev'd up a little as expected. As I was standing there, it did it again about 10 seconds later on it's own. So I stood there longer... about every 5-15 seconds it revs a little like I'm spraying starting fluid by the throttle shaft. It's very faint, but noticable if you're listening for it. So I spray the throttle shaft again right AFTER it rev'd up on it's own.... guess what.... no rev. It must have been a coincedence that it was revving when I was spraying the other day. ou: So now I don't think the throttle shaft is leaking vacuum.... So now what? I started wiggling all the vacuum lines, and just about every one was very loose on the fittings, and effected the idle slightly. They're old and hard, and formed to fit the Holley carb that they were on for so long. So I cut about 1/2" off of every vacuum hose I could get my fingers on and fired it up. Idles steady as a rock now! I took it around the block and it's running pretty strong compared to how it was. I think I just may have it. Crap.. I didn't keep this very short. :gt: OK.. back to the little hose coming out of the firewall... It's black with either 1 wide white stripe thats faded in the center, or 2 thin white stripes. It's hard to tell. It IS pulling a very slight vacuum, but I can't find anything to hook it up to. The other small one going to the "ball" is solid black. I checked and all my heater controls work fine. Unless someone has a suggestion as to where to hook it up, I'm just going to plug it. Any suggestions? Thanks! :beer
