Fellas- It's my Dad's 1949 Buick Super50 Convertible. He's got two Aero Strombergs on a 1941 Edmonds intake to the Str8 8. Trying to Balance the air flow and not sure hot to adjust. Below you will find pictures of the air levels they are each taking in and pictures of the screws for adjustment. I need an explanation on how to do this and I know you guys can help. Here Is the Rear Carb at Idle Here Is the Front Carb at Idle Here are the labeled Screws that I can see Also- The rear Carb's throttle plate is hard to move back and forth, IT feels heavy and sticks as compared to the front. Any suggestions? Thank you in advance.
First you need to take loose the acclerator linkage arms that run to each carb as shown in the last picture, then balance the carb using the idle screw on the throttle shaft that should be located just behind the throttle shaft arms. The screws will have a spring on the to keep them tight. I cannot seem them in your pictures. Once you get them balanced then reattach and adjust all the linkage rods so as to not disturb the what you did in the prior step. The base idle adjustment screws which simple open and close the throttle shaft slightly should be to the far right of screw number 2 and probably on the rear side looking at that picture. Screws 1 and 2 are idle mixture screws. If for some crazy reason that there are not base idle scews on the throttle shaft, then you can adjust the long linkage rod that runs to the front carb to try to balance the front carb to match the rear one. In the center of the rod is a threaded collar with two locking nuts on either side as shown in your last picture, just loosen the nuts and turn the collar to try to balance it and then retighten the lock nuts. However it is possible that you may not have enough adjustment with that linkage rod alone. Hope this helps some, Roger
To use the air flow gauge you have to set it on the front carb and adjust the dial so the red float is about half way up the gauge. With out moving the adjuster, set the whole gauge on the rear carb and adjust the idle speed so it moves the float to the same spot. Unhook the linkage between the two carb before checking. The gauge is checking how much air you are letting through the opening, if the carb is using more air, the gauge shows it. #1 & 2 in your picture are the idle mixture screws. They adjust the air to fuel ratio of idle. They don't have anything to do with using the air gauge. Adjust them for smooth running and clean smelling exhaust. Turn each one in till the engine begins to stutter then back out till it just smooths out. Do all four and keep going back and forth from carb to carb. As you get each one closer and closer the engine will respond better and the adjustments will keep getting smaller and smaller. The idle screw will be somewhere around the linkage or throttle blade. The rear carb needs some attention if the throttle blade is sticking. Shut off the engine and unhook the linkage, does it still feel sticky? Try some cleaner or oil on the shaft. If the blade is 100% closed, it will feel hard to open with the engine running. At this point, I would back the idle screws off till I knew the throttles were shut and not touching the screw on both carbs. Then turn each screw till it just touches and begins to open each throttle blade, go in and out a few times till you know its just touching then go one full turn on each. Start engine and using the air gauge, set the idle speed for each carb, and remember, each adjustment better be the same for each carb or something is wrong. If you have to adjust one three turns and one five turns, you better find out why. Keep jumping from one to the other, double and triple checking each adjustment. Once the carbs are set, adjust the linkage to just slide on with out moving either carb throttle. At some point you may have to adjust the air gauge, keep the float high up in the tube and you will be able see finer adjustments. Your goal is to have each carb pulling the same amount of air which means the throttles are set even with each other. If the carbs are different inside in anyway, you will not get good results. Same for a vacuum leak. Joe
Roger- Thanks for the prompt reply- Im guessing THIS is the screw you were referring to: As I balance the carbs- They should be at idle I'm assuming- And at what level (1,2,3,4) should the red ball be at? There were no instructions with the tool seen in the pictures that I bought from Speedway. As far as the rear carb goes- I will remove the throttle linkage and see if the plate is still resistant to movement to eliminate the possibility of the problem being in the linkage itself as it is a Frankenstein-like creation
That is the correct screw. In the new picture, i now see that you cannot adjust the linkage rod as easily, instead, you have detach it from the front carb, loosen the lock or jam nut and turn the rod to make it shorter or longer once the carbs are balanced. Joe H gives similar and good advice too. Roger
After you get it running, go buy some real air filters, my lawn mower uses bigger ones then those! The red ball can be set at any level, you are looking for a difference from one to the other, doesn't matter where its at. Midway or higher works best. Make sure to hold it down tight on the carb. Joe
Yes, it should be at idle when doing the balancing. There is not target number other than the same for both carbs. The only thing you can change to suit is how high of rpm you want the motor to idle at and that will be the only way that you see a difference in the numbers 1, 2, 3, & 4. If you have a way to check rpm, then a normal idle rpm range would be about 700-800 rpm. If you don't have a way to check the rpm, then do it by ear and by driving it to see what feels right. Roger
Thank you both. Once I get the PS Pump, Water Pump & Harmonic balancer back from their respective corners of the US- I will reassemble and adjust accordingly. Your input was invaluable!! Thank you.
Heres a little FWIW from someone whos been tuning multi carb set ups for 3 decades. Be sure that all of the fundementals of tuning have been completed PRIOR to using your gauges to balance or sync the carbs. Valves, and Timing/Dwell{ if applicable }, even spark plugs must all be within spec before balancing. Remember, any conditions such as poor valve/valve seat sealing, ring/cylinder sealing, end especially vacuum leaks will effect your readings. The ideal scenario, although out of the relm of most shops, is to have a gauge for each carb. Then the balance can be set while watching the drop as you suddenly increase the RPM's. That sudden drop and rise of the vacuum is better suited for "optimal" synchronization. Doing each carb individual at idle is perfectly acceptable for 99% of everyday use. TR
Sounds like you are getting good advice for your set-up. I see that you are running two "front" carbs with accelerator pumps. The original Buick "compound carburetion" using the Aerotype had a distinct front and back. The linkage was progressive. The rear opened and flowed somewhere in the 30-50% throttle range. Since you are running fronts on both ends and not progressive (best I can tell from your pics), you are doing the right thing by balancing them at idle.
The original earlier Buick setup I believe had no idle circuit or screws and no need to balance at idle... rear carb come on off idle. I pillaged some bits from one at a junkyard and found that the spacer below rear carb is actually an air valve, forced open by flow and so reall controlling flow there no matter how far throttle is opened. A fairly heavy weight on a lever resisted opening... Instructions above are excellent, on air cleaners as well as balancing. be aware thhat especially when you are working on a new untuned setup the 3 screws per carb get adjusted together and you will likely work in small steps, going around all the adjustments and working to get idles low and the same. As you lower the idle, the mix screws will need readjustment, and you need to get balanced as you work down toward a low idle.
All terrific information guys. Thanks again. In the photo above provided by 1931av8- I actually have that same Air cleaner. Bought it at a show and had it blasted and powdercoated black. Just sitting in my barn. I'm going to use that. Im going to route a filter to the front of the engine. I'm assuming it will be a much happier engine with fresh air in it's gills. As far as tuning the carbs using the 3 screws, and the little bit at a time method- I'll be honest- It intimidates me. I'm going to print all this out and really pour over it in front of the car. ALSO- On my edmunds intake which is again, pictured above in 1931Av8's reply, There are openings on the bottom of the intake that are tied to the exhaust manifold. Mine have nothing on them. Theyre basically open holes right below the carbs. Im guessing that the heat from the Exhaust manifold was harnessed to further atomize the fuel? Is it neccesary to have these hooked up?
Worry about exhaust heat later...it's spring. To start...assuming both carbs have idle screws, all 3...use the speed screws on the side like post 4. Back a step first...throttle is sticky in aft carb! remove it and figgerout why, lube and wiggle til it's happy. If you remove both carbs...you can put everything back the way it was as you bolt back together...set that screw so that both throttles are open the same slight crack as judged by eye. If you don't remove carbs...back out screw til it pulls a bit of clearance, get carbs fully closed. tighten screw til you sense carb just starting to open (engine off) and try to estimate both as open the same rather small amount. Run in the 4 mix screws GENTLY by hand til they touch bottom...do not use any force. Now run all 4 out an arbitrary 1 1/2 turns which we will hope results in adjustment that will allow engine to run so the festivities above can get under way!
That's not an Edmunds intake you've got there; it's a factory '41-'42 intake. All Edmunds intakes for straight Buicks were aluminum and heated by water. The heater hose was cut and clamped to nipples on the front and rear side of the manifold. You could make a couple heat plates from plate steel to bolt to the underside of your intake and run a heat tube from each header to them.
And it mounts the rear carb low because that position has space for the air velocity valve, which is in a separate block of iron rather like a heat riser valve.
Heathen is right! Sure looks like a cast iron Buick Compound intake to me. Those holes on the underside bolt directly to the split exhaust manifolds used on those 41-2 Buicks with this set-up. You may want the heat if you are not getting complete atomization of the fuel during normal operations in your climate. Study my picture closely. You will also see the iron blocks that Bruce is talking about.
"The original earlier Buick setup I believe had no idle circuit or screws and no need to balance at idle... rear carb come on off idle." Bruce: I have both the Stromberg and Carter rear carburetors for this set-up on my shelf and they all contain idle adjustment screws. Both have ports on the intake side of the throttle valve. They definitely lack a pump circiut in both the Carter and Stromberg rears. I guess the forward pump was supposed to be sufficient to enrichen the rear cylinders! Here's a peak: Inside...
yes you will need a heated intake manifold, as Heathen mentioned, copper tubing will suffice one to each heat box. The rear carb is used as the secondary carb. these intakes work like a 4 barrel. The front one is what you run on but both have idle circuits. the rear doesnt have the pump jet as its only sposed to come in when you have about 75% opening. I have that intake on my 39 Century, and it,s a smooth running setup. The air valve is likely warped as I havnt found a straight one yet, it may stick you might have to do some fileing to get it working good. also check the carb thats sticking it might be warped too.
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