Perhaps the timing is way off and it is trying to fire against itself.??? Can you get a timing light on it when it is running? Target would be 8 btdc or where it idles good then finesse it from there
Get the timing right, and see if it will work on both carbs. You say holding your hand over the intake to the carb helped. Do you have no chokes on the carbs? If not, this is going to make much more of a difference in starting than using only 2 of the barrels. Jon.
I run dual quads on my 56 Ford Y using an Edelbrock manifold. I made my own progressive linkage from parts I had. The carbs are WCFB's from 1953 Oldsmobiles. It runs on the rear carb for all street and cruising. The choke on the front carb is blocked open. When cold I need to floor the throttle to squirt fuel into the front so it will start. The rear carbs choke fast idle works fine until warm. I also use the front carb idle mixture screw and idle speed adjuster. This was a MUST for my set up. I also purchased extended idle mixture screws for the rear carb and set them with a 1/4" wrench. It is a tight fit for a screw driver. Mine has a slight stumble until it is fully warmed up then you can't tell it from a single carb engine. I probably need to keep the choke on longer but I live in SoCal and don't feel I need it. You need to know if your manifold is open enough to run just on the rear carb. A guy I know has a 324 in a 31 5 window and doesn't run progressive linkage.
My first attempt at building a hot rod was a 303 Olds in a Model A. What I learned about Oldsmobile engines and still remember is: Distributor caps that are cracked will not work consistently, check yours. Points gap is often critical, check yours. Check your dist./spark plug wires. My car had 4 Stromberg 48's on a log manifold and yes, I know what backfires look like. Oldsmobile engines run best when the compression is within about 10 psi across all cylinders. Air/vacuum leaks will drive you nuts if you have them, you can soak the base gaskets to your carbs in oil if you don't want to replace them and you can spray oil on the manifold/head gasket (be sure the bolts/nuts that hold the manifold are tight and evenly torqued. Good luck!
I'm not sure. I have not ran any checks. Dizzy cap and rotor are brand new. Plugs on the cap feel loose, but I have made are they are all down and connected. Spark also looks good from the coil to the cap and from the cap to the plugs. I started a conversation with you. Call or text me and we can work out the details. Thanks again. Btw, here's a photo of the set up.
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