Hey guys, hoping you can help the village idiot again. Running 3 97s on a 53 Coronet w/241 RedRam hemi. Right now its running "progressive linkage" (not sure if it's working correctly). She's hard to start but idles well once she's warm. I have fuel pressure set at 2.5. The ploblem is I lose all power when I try to accelerate . She gets very jerky and backfires through the exhaust. Eventually she just stalls. I have never had it running right since I've had it. I have replced the fuel pump and filters, changed the plugs and re-set the timing with a light. Now I'm in the weeds trying to figure out what I'm doing wrong. Do I need to adjust idle mix on one or all 3 carbs? Would I be better off going to uni-linkage vs. Progressive? Here are pics of the driver and pass. Side carb set up. Any advice is certainly appreciated. Sent from my SM-N920V using The H.A.M.B. mobile app
Boy, where to start, huh? Can you give us a little background on the carburetors? Did you rebuild them? Are the floats set properly? Are the acceleration pumps all pumping similar amounts? It sounds like when you step on the gas it goes dead lean. Since it's progressive linkage, is the center carb squirting nicely and immediately when you hit the throttle?
The carbs have been rebuilt, the middle carb is new (replica I assume, does not have the 97 stamped on it). The linkage was just set up by my mechanic, who says they were working well. I'm confident that im getting fuel to the primary, thouth that doesn't rule out a stuck float or some other kind of problem. Unfortunately I know very little about these carbs, and have just acquired this car in the last couple months. Sent from my SM-N920V using The H.A.M.B. mobile app
Vacuum, in the photo nothing since the engine is not running. It's called a Uni-Syn. And must for getting multicarb engines to idle correct. Off idle it's up to you to get them to perform.
I know nothing about the 97 carburetors but I know my Edelbrock AVS2 is supposed to have 5.5 #'s of fuel pressure. I would hook a tach and vacuum gauge and start with the center carburetor and work out. The usual, check for vacuum leaks and look at your initial timing. You will get it-----------------
2x on the Uni-Sin. I bought mine in 1966 to help my uncle tune a 1964 XKE. Still works. I’ve never had any luck setting up a tri power to idle on all three with progressive linkage. I start by removing and sealing off the end carbs, and making it run on the center carb. That doesn’t make it a final setting, but at least it’s running. Then I’ve set the end carbs with the butterflies closed and work from there. I’ve know guys that could do anything with tri power and make it work, but I was never one of them. Hopefully one of them will point you in the right direction.
I like the idea of tuning and running on 1 carb and working from there, thank you Sent from my SM-N920V using The H.A.M.B. mobile app
Just finishing up a 3x2 SBC setup using Stromberg 97's When you open the throttle (engine NOT running) there should be two shots of fuel coming out the center of the venturi booster pipe. If not you have an accelerator pump system failure. The tubes can be removed and cleaned but they usually crack as they have to be twisted. Use carb cleaner and air from the bottom to spray into the end of the tube to clear the junk out. Check out that skirt...on the pump.....change it as they can fold up if not kept wet. There is a power valve at the bottom of the accelerator pump well. standard is a #65 in all three Take the three brass plugs out of the bottom of the bowl on the outside, use a big blade screwdriver. Under the center one is a small brass screw. Remove the screw and is should rattle when shaken. This is your accelerator pump check valve. These clog easily. The main jets are under the outer brass plugs. The end carbs are usually fitted with a # .046 jet. Depending on a lot of factors I usually use an adjustable jet kit. This is not to change the idle or adjusted to compensate for a rich or lean idle, only for cruising WITHOUT the end carbs engaged. Make sure you are using a large jet to allow for adjustment. I use a .078 and work to the lean side. Under the main jets are the main wells, just like a cheap glove.....one size fits all. The main wells are pressed into a slot and DO NOT come out by twisting or turning. There is a special tool that fits inside the end and with a light tap the tube will come out......maybe.
I appreciate the info, added it to my list of things to check. This is forcing me to learn my way around these carbs which is a good thing, maybe[emoji3] Sent from my SM-N920V using The H.A.M.B. mobile app
It looks like your center carb is one of those Speedway 9super7 reproductions. There has been lots of negative feedback on them...do a search here. That might be your problem. As a test, I suggest you move them around and try one of the other carbs as your primary (probably have to use the front one since the rear is missing linkage). See if either of them run better. You really should be able to run around on just the center carb. The outers should be set to only open when you really have the pedal down...kinda like when you stomp on a 4 barrel and the 2nd barrels open up. Get it running good on just one carb, then worry about getting the outer two hooked up. When you set the outer 2 carbs up, you need to make sure that all 3 carbs "bottom" out at the same time. This is done by adjusting the linkage.
I'm liking this idea a lot, if I can get it running good on the primary I would be a happy camper. Just want to be able to cruise a bit while the weather is cool. Thanks! Sent from my SM-N920V using The H.A.M.B. mobile app
Use aluminum cans flatten out as gaskets under the two end carbs. That will totally block any air flow, which will allow you to work only on the center carb. Once you are happy with it, move it to the front and get the next one running till all three run by themselves. Remove block off gaskets and see how it runs. Be sure to set idle speed the same with each carb when in center position.
Sorry to sound dumb, but I assume I also need to cap the fuel inlets on the front and back carburetors? Sent from my SM-N920V using The H.A.M.B. mobile app
No, because there is no air flow to pull the fuel from the bowl. If you have an idling problem after you take out the block off plates you will need to check and make sure the end carbs throttle plates are fully closed and seated. You should not have to adjust the ends carbs to smooth out the idle, in fact the idle screws should be seated closed.........carburetor tuning........a lost art........
Thanks for the info, I just posted a question about how to "block off" the end carbs Sent from my SM-N920V using The H.A.M.B. mobile app
Seems like you're getting advice mixed between progressive and unison linkage. You don't need a vacuum gauge for progressive linkage. I'm not familiar with the Stromberg carbs, but I know with Rochester's the secondary carbs are different than the primary carbs, with no idle circuits. In fact the entire carb base is different from the primary carb base, with no idle circuits. Some guys try to modify primary carb bases to use as secondary carbs, but it's not easy, they tend to leak air around the butterfly valve resulting in idle issues. So, unless there is something different about Strombers, I think you need to sort that out first. As others above have pointed out, you should be able to block off the 2 secondary carbs and just get it running right on the primary carb first, then add the secondary carbs after that. Here's some info that may be helpful: http://www.thecarburetorshop.com/Aftermarkettripowersetups.htm
I am going to go with one carb for now. Eventually i will go away from progressive linkage all together. I think all 3 of the 97s have idle circuits, but as I've said, my only interest right now is making it drivable. Thanks for the input. Sent from my SM-N920V using The H.A.M.B. mobile app
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