I did a search but did not find the much. I have a 4 x 2 intake with 97's...what are the benefits...downfalls of running progressive vs direct linkage? I am leaning towards direct...seems simpler and cleaner looking..... Thanks
I just read a post on this recently and the poster recommended direct linkage. I have no experience on this since I've always run 3x2's. I will see if I can find you a link to the post. What was said made sense.
This is the one Mopar34 was talking about I THINK http://www.jalopyjournal.com/forum/showthread.php?t=240356&highlight=progressive+linkage
This was posted on another site. it was a response from an Edelbrock employee to a guy who had a 2x4 setup and was asking about running either progressive or direct linkage. Take it for what it is worth, the choice is yours and others here may have very valid, but contradictory opinions. *********************************************** [Question:] "i have one question i just bouht a carb tuning dvd because they siad they showed how to tune 2 4's but it did not. so i e mailed the company on the dvd and asked them this is what they said." [Edelbrock response] "I REALLY don't recommend running any kind of progressive linkage between the front and rear carbs on any twin carb set-up. Progressive linkage is great for six pack set ups where one CENTER carb runs the engine evenly up until half throttle, then the outer two carbs come-in later on (progressivly) for full throttle pulling. Setting a front or a rear carb up as progressive can make the front or rear of the engine run lean, depending on which one comes in later. I would highly recommend running both carbs in perfect sync with each other. Adjusting the idle mixture screws a bit more on the rich side for one of the carbs will only cause it to run slightly richer during, and right off an idle, but not at part throttle or while under normal acceleration. Under normal driving conditions, you are pulling from the main jets, NOT the idle mixture circuits that the screws adjust. They call them IDLE mixture screws for a reason Does progressive linkage work? Yes, but as I said.... IF there is a center carb to run the engine EVENLY, and 2 outer carbs that come-in progressivly as you get into the throttle. It is not good for your engine to have one carb running at part throttle while the other is closed. Make them both the same or you're asking for engine damage. Have a good one, Arron" <!-- / message --><!-- edit note -->
The Eldelbrock responce is addressing a 2x4 configuration, and not a 4x2 configuration. 4 barrel carbs are progressive already...as in the secondaries.
If your running a big block or small block with lots of CIs and HP, all four now..YOu run lean on some cylinders with progressive.. Duane.
You are absolutely correct! I apolgize for misreading the question. I think I need to get some sleep before I make any more mistakes. In any case, I hope the 2x4 info is of benefit to someone if not the original poster. I think I hear my select comfort calling my name. <!-- / message --><!-- sig -->
You could make it work well either way. A photo of the intake would help get more specific info in return. If they are four 2's in a row you could stagger two for idle then have the other two for kick in at part throttle. If there is two carbs on each side you may have some cylinders running too lean which was the warning above.
Just to clarify what I mean, if this manifold has a carb over each set of intake runners(two carbs on each side) you want direct linkage, if they are all in a row progressive would be better for economy.
o.k., is it a Weiand WC245? If it is, you will need to run direct linkage to all carbs. Flip the intake over and look at the runners...see the pattern. Kerry here on the Hamb has a few good post about this intake. I am running a Cragar on my 354. The plenum on the Cragar is open which will work progressivly. The Weiand will not work progressivly.
for what it's worth, i'm running twin 2 barrels with straight linkage. i tried progressive linkage at first, and hated it. i went to straight linkage and my engine starts easier, idles better, and pulls alot harder than it did with progressive linkage. my 2 carbs are in line, and i tried the rear carb as the primary, and front carb as the secondary...and vise-versa. the cylinders that were below the secondary carb were always leaner than the ones below the primary carb. i know that because i read the spark plugs. anyway, once i went to the straight up linkage, all cylinders are now the same. by the way, i took the cheap and easy route, and used a vintage speed 2x2 adapter, bolted to a stock intake. i made the throttle linkage myself, because it was real easy to do.
direct linkage is the way to go! but remember this, you have to be able to burn the fuel your putting in your motor. so make sure you have enough ignition to burn what you put in and check your plugs and see how they are burning. you might need to bump the timing a little bit or gap the points a little more, small changes can make the whole thing come together. i love multiple carb set ups and until this motor thats all ive ever run. progressive linkage was nothing but a head ache for me.
2x2's should always be run directly together. Manifold design will be the deciding factor in the choice between direct or progressive linkage. After that, the next thing to consider is driving habits and engine fueling demands under those conditions. Are you gonna race this engine only in the quarter mile, or are you gonna gun it around town and make some driving trips? Anyways, back to the Weiand WC245. Not street friendly but will perform great with direct linkage of all 4 carbs. As a side note, I think there is a Weiand 3x2 intake listed on ebay right now.
With a 354 juice up, I would be worried about it running lean on 4 stock 97s..600CFMs???????. Maybe use the 97s but put larger jets and power valves..Also very important, don't use restrictive air cleaners..Yes, hot spark and a good set of headers to get it out..The engine will love you.. Duane..
To determine jets and power valve sizes you will need to consider your al***ude. Now that you have determined to run direct linkage on your carbies, I suggest you contact Uncle Max here on the HAMB for all your carburation questions. He can answer anything about the stromberg 97's.
jj mack..Your jets sizes are the larger the number the larger the opening..On the power valves it's just the opposite..You'll have to experiment..I wouldn't go any larger then a 48 jet and 63 power valve..Your venturies are only so big.. Duane..
If you have the Tex Smith Hemi book there is a section on setting a WC245 and Strombergs up written by Skip Readio. He's a HAMBer. Pretty good read. I ran the same intake for a while and asked him about the progressive. Evidently the crossovers weren't good enough to cross distribute to the end cylinders. He tried progressive for a while, giving up because the end cylinders were to lean. I took a different tack and made a plenum box that bolted on top of the intake and then put my four Stromberg 97's on that with a progressive linkage. Worked great!
You cannot run progressive linkage on a Weiand 4 X 2 manifold. If you do, you'll starve the 4 end cylinders. You need to jet down the carbs and run straight linkage with that manifold. The runners run from the ****erfly, direct to the intake port. There are criss-cross runner connectors between 1-4, 3-6, 5-8, 2-3, 4-5, & 6-7 but they do little to supply fuel to 1,2,7,& 8 if yopu're only running on the center two carbs. The engine will seem anemic until you gradually crack open the end carbs then it'll wake up. I'm not talking stabbing the throttle, I'm saying just gradually increase the throttle until you reach a point where the end carbs just start to open. A steep hill works well for this test. Once you get all four carbs working, the engine runs on all 8 cylinders. I ran straight linkage on a Weiand for years. It only took me ONE 15 mile trip to realize the progressive wasn't working. If you had a Cragar 4 X 2 manifold, you could run progressive. 2 center carbs plus 2 end carbs. See Tex Smith's "The Complete Chrysler Hemi Engine Manual" http://www.hotrodlibrary.com/product_info.php?products_id=16&osCsid=7c7b3520f693c1ed3f6f09e37533afc2 for a detailed description of setting up this manifold with 4 Stromberg 97 carbs. FWIW, I switched from the Weiand to a Cragar and now run progressive linkage. The fel economy hasn't changed much between the two manifolds because I had to re-jet the center carbs back up again when I switched to the Cragar.
Kurt - You might want to mention to some of these scientists that you're up around 7000 feet above sea-level.
Stromberg 97 power valves aren't controlled by manifold vacuum and don't open until the accelerator pump pushrod hits the plunger on the power valve. The throttle's got to be pretty well wide open for this to happen. The only "issue" you might run into with regards to Stromberg 97 power valves is that fact that they tend to leak and richen the mixture. Unless you have newly manufactured valves, the return spring may be rusty and not up to the task of holding the power valve closed under high vacuum situations and the valve will dribble fuel. Power valves that have sat in the bottoms of old carbs will very likely exhibit this symptom. Power valves that have sat on parts store shelves for decades may or may not exhibit the same symptoms, depending on the moisture exposure they were subjected to. Power valves are numbered by drill size. The larger the number, the smaller the hole. The power valve should open in a low manifold vacuum, on-demand situation. It should not be leaking in a high manifold (cruising speed) vacuum situation. When you stab the throttle, manifold vacuum bleeds off, the accelerator pump squirts a charge of fuel into the bore and the power valve opens allowing more fuel to flow into the bore. When the throtttle begins to close, the power valve closes as well and you return to the carburetor's main fuel metering system for fuel delivery. If you're blasting down the highway and encounter a steep grade, a grade steep enough to cause you to get into a near wide open throttle situation, you will, again, open the power valve as the accelerator pump plunger will contact the power valve and open it. On a stock flathead, this would occur at approximately 70 mph.
Yup, what these guys have said. Desoto, can you give me some details or pictures of your generator bracket? I need to figure that out soon on mine.
desoto: Thanks for the primer on power valve operation. The Skip Readio piece in Tex Smith's book suggests (when running 4 97s on a Weiand manifold) stepping down to size 35 jets and working up from there. However, he doesn't mention changing the size of the power valves. Is it safe to ***ume that I should keep the stock power valve in all 4 97s when running the Weiand 4x2 manifold? Thanks in advance.
The Jalopy Journal
