I finally finished doing a lot of work on my car last week. More importantly than the cosmetic upgrades, I was looking forward to the new four barrel carb that was replacing my two barrel. Whenever someone on the board begins to look into making a carb swap, everyone here on the board says "You will really feel the difference." I was really excited about my new found secondaries, but I am sad to say they have really disappointed me. I'm rocking a completely stock 350 with the iron intake and a 750 cfm (I believe) Q-Jet with 2.5 dual Magnaflows, ST-300, and the stock non-posi rear gear (I'm not sure exactly the ratio is), and I have noticed hardly any difference over the two barrel. Off the line, when I do happen to spin the right wheel, I've noticed it will drag a little longer than it used to, but there's been several times when the tires did not squeal one bit. From a roll, don't even count on the tires breaking out, 'cuz it won't happen. And most depressing, WOT at 40 mph, the thing accelerates like the two barrel did accept now it's twice as loud. In super busy traffic today, I was merging out of the median into traffic and I slam the gas, and the lady in the '98 Grand Prix BEHIND me kept right up with me. On top of all this, I rolled into a deserted parking lot the other night to throw some smoke around with my friend, and the tires would not spin at all (do the drum brakes make a difference?). Maybe I was doing it wrong, but with my left foot on the brake and my right giving it all the gas, the front end just sat up and made some serious noise. I do not know if the tires would spin before the carb swap, as this was actually my first time in a year and a half trying to do a burn out because I try not to bang on my beast. When one of my dad's employees ran an errand in my car last week before I got the car back, he said the new carb felt really peppy. I asked him how the secondaries felt and he said he didn't know because around town he couldn't get out of the primaries because the tires would not bite. I hope I don't seem like I am complaining at all or anything negative like that, but I am so excited about this car, but I feel like I should be getting more out it. The car has not been TRULY tuned up, but it's pretty close and I plan to get it properly tuned next weekend. Most of all, I wish the tires would break out a little bit more and I wish I could feel the throttle from a 45 mph punch. I have no idea what is going on here as I am no car expert and most of what I know is fueled by what I read here. All thoughts are greatly appreciated. Please help me. Jacob
Hey Jacob, I swapped a Q-jet on my 350 and had a similar problem. I even started a thread about it http://www.v8buick.com/showthread.php?s=&threadid=34730 There's a lot of helpful information there, but unfortunately I havn't been able to work on the car (spring break in only a week and a half away now! :Brow: ) I am planning on ordering a crane vacuum advance kit and hoping that helps, but I've also heard that people with the stock highway gears shouldn't expect a big increase with a four barrel.
Jacob, What is your timing? When is all of your mechanical advance in? I don't know if you are running a stock distributor with the stock advance springs in it. If so curving the distributor will make a huge difference. Also, if you have a low numerical rear in the car, the secondaries will not come on until you get the engine RPM up. Q-jets are air valve secondary carbs. Even if you punch it from a dead stop, the airvalves will remain shut until the engine requires the air flow. If you have a stock torque converter, that also holds the RPM down from a dead stop. The ST-300 is a 2 speed trans, so 1st gear isn't that low. You just have to work on your combination a bit. Start with your timing.
Something is wrong. Even after 38 years of driving it, I still have to feather the accelerator to keep my car from peeling out. The car still has the 2.78 rear. And, that was also the case with the stock carb and ST300. You should feel the extra barrels kick in anytime you stomp on it. Mine has always kicked passengers heads back even with the original carb of about 550 cfm. A late model Gran Prix has a 0-60 of about 6.6 and will eat your car for lunch, and that should be no surprise. The ST300 switch-pitch has some unique linkages. You may want to test them out.
Harry, that passenger head action is exactly what I was looking to add. Larry, I do not know what my timing is right now. The finishing touches were put on my car by a pair of Chvey guys while I was at school. I am using a stock distibutor that was put on last summer. I know it's all over the board, but what would you recommend for the timing and everything else? In regard to the air valve secondaries, would it be wiser to use a carb with mechanical secondaries in order to open the secondaries sooner for such a weaker combo? Am I correct in that thinking? If I am correct, would that just use more gas? Steve, how much was the kit? Does anyone know if this kit may be of benefit to me? Thank you guys, I appreciate everything. Jacob
I have a moded Q jet with manual secondaries, secondary air flap is only control by the spring load / what ever you call it. NO vacuum stuff, Remove the air vain guard, and run 1 1/2" of spacers. I also run a true cold air system via a missing headlight. And its a blast. I do some timing tweaks and look up tweaking a Q jet. Smiles are only a little bit of work away.
Summit has the kit for $22.88, I think Jegs sells it also but its a little bit more expensive. You can either get it from the catalog or their web page. For a points distributer, its crane cams part # 99601-1 If there is something wrong with the carb, then it won't fix that, but it will help get the car running where its supposed to be. I lot of people on this board recommend it, so whats good for them should be good for all of us.
750cfm! If you slam dunk that open (Q-jet made all mecanical) with a 2-speed trans and a stock converter the stock engine will se a to heavy load an create a flat spot giving you no more fun than you got right now!:shock: Correct Timing is everything (almost) :rant: and a properly working (in this case) Q-jet is the rest.... First, make sure that the timing is set right, guessing wont do!:Smarty: If that didn't solve your problem, tune the carb, don't try to make it all mecanical or x-change it to one that is....tune it!:3gears: A god working, right tuned vacuum sec. carb is the best on a engine that sees heavy loads, and as the engine revs up it opens up the sec. with no flat spot or delay in opening, and giving you good mpg as a bonus! If right tuned that is...:TU: Thats just my 2$... Lars :Comp:
Jacob, There's nothing wrong with the stock Q-jet, it's the best carb for your application. Timing means alot. If you don't know where it is, I'd say that is at least a big part of the problem. Get the Crane adjustable vacuum advance. Use the 2 silver springs. That will get your advance all in before 2500 RPM. What you want is 12* initial, 32* total advance. Limit the crane cannister to 8*. That should set you on the right track. Get the distributor recurved if necessary.
Allot of of guys don't like the full manual Q-jet but mindless mashing of the pedal is not that great. But allot of people like it that way. The carb has to do allot of the work and its really just fake as youhave it mashed but its slowly doing it own thing. you can stomp it off the line but the carb is not wide open. For a full manual carb you need to have foot control. You gotta learn how to drive the car with your foot but once learned I find its much better. On the street its a blast, if I was doing searious drag racing, The other way might be more reliable in the time slips. I just like having total control over the carb and I drive it with my foot. Kind of like shifitng your auto trans, just mindless mashing the pedal in D isnt allways the most fun. Like having a carb on a dirt bike where you can by cable jerk that needle out of the jet and flow fuel, or like on a crusier bike you really only control the air flap and load and vacuum raise and lower the needle out of the jet. Both can run very well but I perfer the direct connect action. Takes more work form the drivers but its a blast. Its how everyone sets thing up in highschool and once learned it was better on the street. On the street Ill take out a well tuned vac control carb cars 9 out of 10 times. I use to have a blast in my old 76 Olds Gutlass 350 and a moded manual carb. But Id saying timing is his major issue. We also use to power tune back in the day. power brake it in some stones while another guys adjust the timing.
one more important thing.... (engine not running) have a friend put the pedal to the metal and then you make sure you got no movement left on the carb. (that it really is able to open up all the way!) Lars
With the engine off, go WOT with it and make sure that the secondaries can open up...Sometimes the carb won't be lined up properly on the intake and the secondaries won't open...
Thanks guys. My G'pa and I are actually going to tune it according to your recommendations here in the next two hours or so, so I'll see where that gets me. Thank you. Jacob
Jacob, keep us posted..... Gumby >If you see a file you want removed just ask, if you want to add a file just ask. I save every Buick related file I come across there. Link all you want to the files.< "buick pic. directory"? http://www.buick.viragotech.com/7.JPG .....isn't this one a bit of ? o No: Lars
I just finished the tune up a few hours ago and as it turned out, my granfather was actually the one who did the timing the first time and it just so happened the car was already at 12* initial and about 25* total. We checked to make sure the carb and everything was lined up as you all have suggested and everything was OK. On my way home, I was at a jog of about 40 and I noticed if I'm rolling at part throttle and let off about a third of the pressure, then slightly regain that third and then smash it, it will hit a lot harder than I initially thought. Of all the suggestions you guys gave me, you forgot one thing: Driver's error :laugh: . Should I still look into the Crane adjustable vavuum advance? If anyone else still has an idea floating around in their head, float it my way. Don't get me wrong, I'm still very pleased with the performance of the car and I love driving it, I'd just like to get the most out of what I have. Thank you, I appreciate all of your attention. Jacob
Two things, make sure your mechanical advance is not binding or sticking. This could be your problem. You should have 30-36* total advance. Is everything lubed up properly in the distrib? Also check carb idle air/fuel mixture settings and adjust for the highest manifold vacuum. Then re-set idle speed. OK one more bonus, ck accellerator pump for a big, fat squirt down the bores (not running).
Jacob, How are you determining your total advance? You need at least 30-32*, and you need it early, by 2500 RPM. That is the secret to getting the most performance out of your Buick. However, if you get your advance in early, you need to use the adjustable vacuum advance, and limit the amount of vacuum advance. Do you have a dial back timing light?
Larry, I was using a Sun timing light. My initial was right on at 12 and I determined the total by opening the throttle with my hand and watching my timing mark shoot up. It's only a guestimate, but it's in the lower-mid 20's. This is my daily get around, won't 32* be way too much? I was under the impression that the 30's were for...quick 1/4's, not trips to return videos??? Jacob
