The throttle blades are all the same size, it's the venturi that regulates the CFM on different sized 2gs. Increase that, and it will improve flow. Otherwise, there'd be no such thing as 4 different large base CFM sizes all using the same throttle blades! Anyway, yeah a 4 barrel will improve power a bit, depending on how restricted the engine was with a 2 barrel, but only because it raises the powerband up some. Torque will peak much higher, but hp won't peak much higher. It tends to narrow the powerband a little when using a 4 barrel on a stock engine. Like I said earlier, pros and cons. If he keeps his ST300, I advise against a 4 barrel unless he doesn't mind his takeoff suffering. His goal was to squeeze a bit more performance out of his current setup, not rework the entire drivetrain. He needs to know all the information and not just selling points to parts. If he was to have someone rebuild his small base 2g and modify the venturi, he could get about 350 CFM out of it, which would do nicely with his setup along with a scavenging "Y" big single. Or he could do the 4 barrel setup. His choice. Knowing what to honestly expect though is being fair to him. Gary
I'm with ya Gary just wanted to rattle your cages a little, lol. Yeah I got sucked in too so I am no different. Actually I thought the 4bbl would have smaller primaries than the 2 bbl and would help with some gas mileage. I think it is not a square bore carb with the 4bbl so might be limited on carb choice here. I think some people here do not know what the heck we are talking about sometimes with all the different things to try. Wasn't that a Carter used on the 4bbl engines or was it a Rochester. I think it is a Rochester back then. I guess we have nothing else to do but shoot the bull. lol Just think if we were all in the same room together. lol
Rochester 4g I think they called them. Square bore. They may have used some Carters too, I dunno. I'm not as familiar with those. It'll help gas mileage to use the 4 barrel, but as long as you can keep RPMs low and throttle blades barely open, the 2g doesn't do too bad on gas either. It won't do quite as well as the 4 barrel, or a Qjet, but the difference isn't like day and night, unless you keep the primaries (or 2g) open farther--then the 4 barrel makes a bigger difference...but then consider if you stay at full throttle a lot, the 2g will get better mileage than any 4 barrel! lol Also to consider is that partial throttle power is increased with the 2g because of this. This makes it good for trucks, heavy cars, or steep highway gears (transmission and/or rear end) because it keeps torque down low. Those straight 6's did well with this because their peak torque hangs out around 1500-2000 RPM. The Ford 4.9 litre (300) inline 6 is a beast because of this. Big cubes (for a 6) and over 300 ft. lbs. down low. It'll pull a lot more than the 'rated' towing capacity. The one thing people are overlooking is the improved fuel distribution of a centralized set of throttle blades vs a progressive throttle setup, which all street 4 barrels that aren't dominators are. A Holley double pump helps to offset this with the secondaries acting like the primaries when you get the opening shot. Almost like having two 2 barrel carbs (which is another setup people have on some of their street'rods'). Gas mileage doesn't matter on those. It's almost like having a primitive fuel injection system. With the 4 barrel, the primaries are usually offset a bit making some cylinders get less than optimal fuel than others. This will cut into gas mileage and overall efficiency too, offsetting the gas mileage advantage the 4 barrel might otherwise have. The Big blocks have the primaries more centralized on stock intakes, so will be more efficient when using primaries. Take a look at the intakes. Absorb all the details. Pros and cons. Talking about this and that may seem like a waste of time, but there is much information to be gleaned when you combine the minds of educated and/or experienced people. We all have something to offer the community. We usually do eventually get around to answering someone's question though. lol Good to see you loosening up a bit. Nice chatting with ya. Gonna get ready for work in a few. Gotta shackle myself to the corporate machine. lol Gary
sorry, but going to a 4 barrel and dual exhaust is the first thing one should do if you want more performance, that is what the factory even did, and listed a 25 hp gain. both mods will help gas mileage. that is my story and am sticking to it. what is next a 1 barrel is better than 2 barrel.
I for one, enjoyed the reading in this thread! My blue '66 came with the 2 speed and a 2.93 rear. My first time at the track in Bowling Green 1983, it was doing the 1-2 shift just before the traps, bogging a little as it did so. One run I left it in first and didn't shift until I hit the finish line! I still have the time slips. Best that day was 14.67 @ 95.13, worst was 15.23 @ 92.3. So even the 'one-speed' trans run wasn't too bad! I eventually got the combo down to 13.60's. swapped in a 3 speed st400 trans and it ran about the same. I did enjoy driving the 3 speed much more than the 2 speed tho. For my '66 Special with 300, I found a aluminum '64 intake for like $35. Yes, the intake ports are smaller but I opened them up to match the head and had to block off an exhaust passage to make it work. Can't say if there was a performance increase or decrease, it was over 15 years ago. I didn't like the 2 speed in this car either. Swapped in a Richmond 5 speed with 3.28 first gear and 1:1 fifth. Works pretty well with the 2.79 rear. Car is real fun to drive now!
You're sticking to the old paradigm because you have an intake to sell. I have nothing to gain by claiming one or the other. All I'm stating are facts and scientific knowledge. Factory ratings were inflated for marketing reasons. Yes, the 4 barrel will give more performance, but at a higher powerband as I've said before. The 2 barrel will give better performance at lower-mid RPMs on stock applications. Either one is highly dependent on gear ratio setups for optimal performance. Slapping a 4 barrel carb on a 2 barrel drivetrain will lower takeoff performance. Sorry. Factory used dual exhaust because it was cheap and simple, and the pipes were small. I did a small writeup on 2 1/2" mandrel single pipe outflowing 2" press bent dual pipes. Either one would do fine, so sure dual exhaust. Whatever. The factory also used numerically higher gears with the 4 barrel setup to help compensate for the higher RPM powerband. This will raise RPMs at cruising speed vs the 2 barrel setup. Gas mileage won't be much different, and there are some who even say the 2 barrel got better mileage. When considering a square bore carb I can see why this is. I'm simply listing the pros and cons in an honest, direct way. You don't have to agree with it. It's clear you do not understand the basics of fuel delivery, but that's ok. Not many people do. I'm trying to explain a couple basics, and I expect resistance, so it's ok. I'm just trying to help. But what I won't do is inflate something for the sake of selling when it will harm performance unless he puts in a different gear ratio. Nothing personal. Just the facts. Increasing the size of the 2g will lessen the performance gap that adding a 4 barrel would anyway, and would have more low-mid range torque on a stock engine vs the 4 barrel. Something tells me I'm wasting my time trying to explain things further, so I'll let you have the last word and leave it at that. Peace Gary
your right i do not agree, no big deal, just telling what i think. but you are dead WRONG about me trying to sell the intake. just happen to have one. i offered it to any one that really wants or needs one. the intake is not listed for sale any where and never was. have a basement full of parts non are on v8 buick for sale or any where else for sale for that matter. like you said just stick to the facts. he was asking for more growl thats all he said nothing on low end. Gary, you are very smart and like reading your posts and right with you on the st300 and 99% of everything you post, just dont agree on the carbs or exhaust. i wasnt kidding when i asked about the 1 barrel there must be some pro and cons with that too.
Not really. You need at least 2 barrels, one for each side. Otherwise, you'd have a single plane with a huge one barrel carb. lol When GM first went to fuel injection, they used the injector spray nozzles, 2 of them, which were huge compared to the 2 barrel carbs, and replaced all carburetors at the time, even the 4 barrels, and gave better overall performance and fuel economy. Then they went to direct port injection so each runner got its own nozzle. Anyway, yeah. Bigger 2 barrel is better performance with existing powertrain. Adding a 4 barrel will weaken it down low, while improving it in the higher RPMs, but with a tall street gear, would be inferior to a larger 2g for general street use/everyday driving. Reread my posts about the pros and cons. Here's a video clip of someone using a 350-2, stock compression, stock CFM, etc. Gives you a basic idea of what they can do. I know it's not a 300. It's for reference. https://www.youtube.com/watch?v=pvMrc1aciNQ Gary
I get what Gary is saying about the 2bbl vs the 4bbl. With the 2bbl the bores are slightly larger so when you open the throttle on those it will NOT have to be opened as far as a 4bbl would and since the 4bbl has a smaller opening it will have to be opened a slightly bit farther to stay at the same level as the 2bbl. Hence the 2bbl will have slightly more torque on the low end since it is not open very far. So it would make sense that with the 4bbl and dual exhaust you might get overall more hp and probably more torque but will probably be in a higher rpm range as compared to the 2bbl. When you think about it, this is why the Q-Jet has such good response on a 350 or 455 as compared to a dbl pump carb. But past a certain rpm the dbl pump should give more power but will probably be at a higher rpm. Then all of this will boil down to gear ratios in the trans and in the rear. In the end the 4bbl car should be faster but in a cruise mode where you use 1/8-1/4 throttle opening the 2bbl should have more torque in this area. I bet the 2bbl will get the right rear tire burning quicker and faster than the 4bbl but once the 4bbl kicks in all the way it will probably smoke its a** off...and stay there till you let off. When I had the 2bbl on the 350 it would smoke that right rear quickly but the car would catch up quick too but with the 4bbl (Holley Spread Bore 650 cfm) it took a little more to get going but once it got going it stayed there and the car would not catch up as quickly. I think I had to get into the secondaries to get the tire burning. Then it would burn a long way about a half a block. Bought a lot of right rear tires in those days. bye bye TA radials, that's singular radial. LOL. I do miss those days take me back to 85. The U-Tube post was pretty good mine would do the same back then and the car would start to catch up but once that 4bbl GOT going it would not catch up and stay there and burn like mad. Watch the video after the Buick and you see some cars, like ford and chevy can't even get the tire burning and the guy in the Vette says there goes 600 dollars and he THOUGHT it was going to be tires but instead it was all clutch burnout. lol Too Bad there wasn't one of those old Wildcat Buicks there with a 425 motor it would have NO trouble burning the tires. This is all your fault GARY, I am blaming you for all this insanity here. lol
I have to agree with Gary in this case because typically the year car we're talking about with a 4bbl carb it had higher compression and a lower gear ratio(higher numerically) to compensate for the lost low end off the line performance that would occur with a 4bbl vs. a 2bbl carb. Being only 300 CID the engine needed a higher compression ratio and a steeper rear gear with a 4bbl to have the same take off as the lower compression version 2bbl sbb 300 and compensate for the higher RPM power range. Of coarse if a sbb 350 was converted from a 2bbl to a dual plane 4bbl with an 8:1 compression engine off the line performance would probably be close to the same just loosing around .2 in the 60 ft times but making up for it as RPM increases. That extra 50 CID is more substantial for being able to keep the low end torque from dropping off than most people would think it would be. Just like the extra 33 CID on a sbc from going from a sbc 350 to a sbc 383, the extra torque from that combo with the extra stroke can be insane depending on the extent of the build. Especially considering weight to power ratio with the 350 vs. the 300, like the old adage goes "there's no replacement for displacement"(the saying should be is more valve area plus more air flow plus more RPM is the only replacement for displacement, but that gets to expensive for a street car), not to mention that a non-ported 350 head will out flow a max effort heavily ported 300 head while maintaining velocity. Derek
I think you may be right. lol Oh well, still a good place to chat it up about the subject(s), and people can (maybe) get some questions answered. Agreed with Derek and Guy, with the addition of a couple things: The 2g has considerably larger throttle blades than your typical 4 barrel, especially the Quadrajet, particularly when it's the large base 2g. You can get them to flow 600 CFM afterall. Larger means less throttle opening for similar air/fuel, so you can get similar mileage as long as RPMs are down. Fuel atomization is more efficient though with smaller bores and opening them farther, which is one of the reasons the Qjet is hard to beat gas mileage wise. But that's only when you consider the carburetor. Consider its location, and things change a little. The primaries on the 4 barrel sit farther up closer to the front of the engine, making the back cylinders run a little leaner when using primaries. Remember there's more to performance than full throttle, which is where the 2g shines. It's not bad full throttle either. The carb sits right in the middle, ensuring all cylinders get equal amounts of fuel (or as close to as possible), making it more efficient this way vs the 4 barrel primaries (when considering economy). All things considered, the 2 barrel isn't a bad choice for someone, and is even better with modified venturi's and jets. There's been a lot of thought put into this with circle track racers, who are limited to 2 barrels due to ruleset used for that class. On the Youtube video he backs off of it and still laid down rubber effortlessly. That's how my old Skylark did it too. I could burn the tires off that thing if I wanted to, and it didn't stop at higher RPMs. People underestimate the Rochester 2g I guess because no one ever bothered with it. It's always been 'add a 4 barrel and dual exhaust' for many people, trying to get performance increased. This is fine and dandy, until you realize your gearing is crippling what could otherwise be a hot combination. The 2g doesn't need gearing as much, because torque is down low. All factory 2g engines came with the low compression variant too, and look how well they did with just that. Bump compression to '4 barrel' specs and see what the 2g does then. Increase CFM on it and get exhaust flowing better and see what it does then. I'm thinking many of you guys would be shocked. There's a reason people thought my 350-2 was a 4 barrel engine, and not just because of the way it sounded (2g can sound a lot like a Quadrajet). I spanked many an ass with that old thing, people who thought adding 4 barrels and headers and cams would be the solution to performance without properly matching their parts. The looks on their faces was priceless. Gary
This is another topic. The nailheads had tons of torque down low and did amazingly well with highway gears and the ST300 because of this. Think about it. It backs up what I've been talking about. Low RPM torque and tall gears. Big blocks, nailheads, 350-2 with high compression and large base 2g. Take your pick. There's more to street performance than horsepower. On the street, torque is King. In the real world where things happen dynamically and you don't have the luxury or time to set up your machine ideally in a straight 1/4 mile line, much happens on the street that is unpredictable and you have to be able to react and adjust on the fly. Your car needs to be able to do the same. According to my dyno program (which gives a general idea, of course), a bone stock Buick 350-2 with high compression, good exhaust, and a 500 CFM 2g produces 399 ft. lbs. from 2400-2800 RPM, with over 375 ft. lbs. from 1800-3800 RPM and 277 hp @4500 RPM. This is raw data results, and does not consider blueprinting or massaging techniques, so the figures would actually be higher than this. Add in a Crower level 2 or 3 cam, and you will get even more out of it. It's something worth considering for those who enjoy street play with 2 barrel stockers no one would ever suspect of being a performer. Talk about a sleeper. "It ain't nuthin but a stock Buick 350 2 barrel with single exhaust..." I am the Paradigm Shifter, afterall. :Brow: Gary
For those of you who still have doubts about 2 barrel performance, here's a little dyno clip from Youtube. There are others like it out there. This one is 320 CID v8 spinning to 8100 RPM and produces 527 HP. Not too shabby for a 2 barrel eh? https://www.youtube.com/watch?v=u2H1vSn7Jcc Gary
You know for the 2 bbl racers there is an air cleaner made to compliment this and this was the K&N Flow Control air cleaner. it directs the air right down the carb. I have the 4bbl version and is 4 inches high and 16 inches across. The air cleaner lid directs the air down the carb. Supposed to be a 10-15 hp add on. The race shop told me they were getting 10 more horse out of the engine with it.
Did some calculations, and came up with some results for the record. Not that many would be interested, but hey you never know. All calculations were made using the same engine as the stock one I described, with compression matched to bring all comparisons to approximately 7.75:1 dynamic compression ratio. Static compression ratio translates to 10.21:1 for the stock cam, 9.22:1 for the Crower level 2, and 9.81:1 for the Crower level 3. Results for Crower level 2 came to 407 ft. lbs. @2500 RPM with 266 hp @4100 RPM. This is +8 ft. lbs. and -11 hp vs the Federal Mogul CS647 cam. Results for Crower level 3 came to 401 ft. lbs. @2800 RPM with 287 hp @4600 RPM. This is +2 ft. lbs. and +10 hp vs the Federal Mogul CS647 cam. Might as well stick with the Federal Mogul CS647 cam when considering extra parts/cost and loss of longevity. Then again, as others have pointed out in the past, the dyno program may be a little off with the comparisons. I'm sure the RPMs would be similar as shown, with maybe a few ft. lbs. or hp difference at most. The trend we see though is the Level 2 cam trades torque for hp, narrows the powerband a bit, while the Level 3 increases torque and hp a little, while retaining a similar powerband, albeit slightly narrowed. Again, these are raw figures without taking other factors into consideration, so figures will be higher on an actual real dyno. Bottom line is (no matter which cam you use) you get lots of torque down low with respectable street hp, ideally suited for any 2 series gear ratio. Would make an excellent truck/towing engine with 3 series gears. You could drop compression to factory specs for regular gasoline usage, at the cost of some power. Would still be pretty stout though, even with that. I mean, come on. 400+ ft. lbs around 2500 RPM is pretty damn good. Low comp would still put it around 375ish. There's a lot of new trucks out there that don't even have that with those small new generation v8's. This is one of the reasons I was contemplating using the TBI system on a Buick 350. Chevy direct swap over to a 4 barrel intake, it uses the secondary openings with an adapter plate. Chevy low comp stockers strain to get 330 ft. lbs. using similar CID (350), and many of them less than 300 ft. lbs. (i.e., 305)... Research shows these OEM units flow around 500 CFM. You can get one from Holley that'll flow 670 CFM. Dyno program claims that by adding this (the OEM 500 CFM unit) the stock cam gains 7 ft. lbs. and 14 hp over the Rochester 2g 500 CFM, putting power at 406 ft. lbs. and 291 hp. Using the 670 CFM unit would produce 409 ft. lbs. and 298 hp. Not a big difference for the extra cost of the Holley unit. I'm sure real world results would be better though. Adding small tube headers puts torque around 425 and hp around 315. This is with the Federal Mogul CS647 cam. Not too bad. Go go gadget fuel injection! lol Gary
Nice info Gary and even though the OP has abandoned the thread we should at least try to stay on topic with the sbb 300 engine theme for this thread. Can you do any of those dyno calculations with the sbb 300? That would add a lot more to this than the 350 simulations, thanks. Derek
You're right Derek. Sorry about the sidetracking. I get carried away sometimes in my own world. I don't have data for the 300. I'd need head flow numbers at varying lifts, which I don't have for it. I'd also need cam specs on those engines, which I also don't have. It may be a while to do those calculations, that's if I can get the data. Gary
That's ok Gary, here is some ported 300 head flow numbers in this thread if that helps; http://www.v8buick.com/showthread.php?260446-Matt-Lesoine-s-(Big-Matt-on-V8-Buick)-300-build Maybe subtract 20% flow to get closer to what stock might flow unless Sean can chime in with actual un-ported flow numbers? I'm sure you can find the cam specs for this engine, lets see your magic!(if you have the time?) Thanks Derek
I'm gonna play devil's advocate here and say with a SP300 trans (hi stall speed 2800rpm or so) and 2 series gears, The rpm range is gonna be 2800-5000 rpm (80mph or so is 1st gear!). In that range, a 4 bbl and hotter cam will provide a performance edge. The 300 is only gonna see 2500 rpm in low stall/easy driving situations. I do understand what you've been saying.... mild cam gives low rpm advantage in normal street driving. But in the case of the sp300 we're talking low gear only at WOT and street speeds....that low rpm torque isn't a factor. Mid-range power may be best. We would have to plot rpm vs speed to determine what would be optimal for a 300/ st300 at WOT..... then determine the best cam and carb. I will still say a 5 speed manual, 4 bbl and dual exhaust is a great swap for a 300 street car!:3gears:
