I could not find specifics on this subject in the search. 97 experts please steer me in the right direction. I'm running a 1956 Buick 322 Nailhead, in a model a coupe. The intake is a 6x2 Offenhauser log manifold. I was planing on using, only 4 carburetors, and block the two center ones off. Question is: What size jets and what size power valves do I need, specifically, for this engine at my altitude (Los Angeles, just above sea level) Another question I have, is: The emulsion tubes I pulled out of all the carbs, have some differences, some have 2 holes and some have 4 holes, just before the end. Which ones are right for 97's??? I appreciate your help Thanks, Chris
I see why your called the "Missing Link"..Strombergs have power valves.. I would start with the stock jets, .045 and .065 for the PV.. To balance the 97s use the same two emulsion tubs, ie..Two holes or 4 holes in all the 97s..This keeps them balanced.. Hope this helps.. Merry Christmas.. Duane
Thanks, Duane. I will use the stock configuration as a base line. If anything, can I expect to leave the power valves alone and just change the jets? And if so, at my altitude, would the jets be bigger or smaller?
Hello..I'm a believer in the jets and power valves need to match..if you go two sizes larger or smaller on the jets the power valve need to match..Remember, bigger the # on jets the hole is bigger. On power valves is oppsite, smaller the # bigger the hole.. Your at sea level, .045 jet and .065 PV,
That might be a bit much with his combination. I would probably try to go down on the power valve and a little smaller on the jet as well. When I had the stock Hemi in my Model A I had 4x2's in a line, with 71 power valves and 43 jets. It ran really good for a stock motor, I would think the Nail head would want the same, or less. I really dont think the 322 is as efficient as the hemi. Jimmy White
On my nailhead im in the process of setting up going to run all 6 with the stock float level and power jet,reducing the main jet to .041,setting the accelerator pumps on the outboard carbs on the long stroke and unhooking the the pump rods on the centers.Dont try to correct poor throttle response by richening jets or it will sting you on the top end. Some carbs tend to lean out at the top end other designs actually richen as airflow through carb is increased the ee1's lean out.
Interesting stuff. I guess I must have had those super-secret mega-rare 97's, you know, the ones without power valves. My bad. I never refered to those items as power valves. Was there ever a power valve by-pass insert?
Far from an expert but, I'm thinking a good place to start would be .044 mains with # 69 powervalves (otherwise known as power bypass jets). If you have the time and inclination - and since all of your mixture is going down those big logs into the same dark hole, you can actually stagger different jet sizes in the same carb. As for the 2 hole vs. 4 hole emulsion tubes: The 2 holer's came about in the 1950's when Bendix got into the mix. Some were Southbend and some were Elmira center-sections. The reason for the 2 holes was to compensate for the smaller bleed holes in the top of the castings, adjacent to the idle jets. Like Duane said, no worries as long as they're all the same. Now comes a potential glitch: If all your carbs are the same, meaning all those little airbleed holes are the same size - fine. If not, and you find some holes are smaller, it's a good idea to drill them the same size as the bigger ones. You have to understand the theory of High Volume = Low Vacuum vs. Low Volume = High Vacuum. Hope this makes sense. If you need any more 2 hole or 4 hole tubes, I have a drawer full, freshly acid etched and cad plated. PM if I can help.
I think the biggest problem is people tighten the jets to much and crush the emulsion tubs at the holes. Be sure to check them. I find more of the 4 hole smashed because I think the integrity of the tub in gone with for holes rather then just two.. uncle max is right, make sure they are the same..You want a balanced Stromberg. Both venturi sides need to be the same..ie, jets, emulsion tubes, idle jets(check openings at the discharge end).. Hope this helps.. Duane..
Great info guys, somebody should write a book on the Strombergs, not just about rebuilding them, thats fairly easy, but also have section that shows tuning procedures, and jet/PV, recommendations, depending on cubic inch, intake manifold style, altitude, etc. Just to clarify: Higher number on Power valves, means they're smaller, smaller number on jet's means they are smaller also??? Correct. And common practice is to drill out, jets to enlarge them, during the tune up stages??? Right?
You are correctomundo about the sizing of jets and pv's. BUT, if you're going to drill the jets, go undersize with the drill and then ream them to the proper finished size. Otherwise you'll end up with hourglass or egg shaped holes. Just get new jets in the size you need, they're cheap. Adjustable jets are a huge pain in the ass: After all, where's the baseline? OMO
Adjustable jets can be a pain in the "ass". Most adjustable kits come with .050 jets. I've found that a 1/4 turn out is a good start.. When working on a dyno machine they are great, no changing the jets..When working several carbs it does make it easier. Taking the body off the base and removing the plugs then the jets is very time consuming, especially with 4 or more carbs.. Also, with adjusters the needle needs to match the jet, very important.. Duane..
I don't think you're going to be happy with the results. Blocking off the center carbs and running the end carbs is exactly backwards of what Offenhauser would have told you in 1955. The original start/idle/cruise venturi area of the Buick was only slightly larger than a single 97. You have 4. The key to low speed part throttle response, mileage and smoothness is the smallest venturi area you can get that permits highway speed (example: QuadraJet), with all the remaining venturi area available by progression only. By running all 4 end carbs you have a choice: A. rich mix: good response, black plugs, 5 mpg B. lean mixture: no response, clean plugs, 15 mpg Yes, yes, I know - your uncle Billy Bob ran twelve 97s on his Wills-St. Claire ambulance and it did 300 mph.
You knew my uncle?............................................. I also have a Nailhead with six 97'S, I am reading this with great intrest.....thanks.
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