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SoCalCoupe · 10-30-2022, 02:44 PM

Started over and got myself sorted out with the idle mixture screws and settled on 7/8 of turn open on each. Got the throttles re-synched with the Uni-Syn.

Don't think I have a vacuum leak; closing off either carb kills the engine. Still idling a little fast though even with the idle speed screws backed all the way out. When I apply pressure to the throttle lever it slows down the engine speed a bit and one of the accelerator pump rods still binds with the throttle lever. I'm thinking that whoever rebuilt the carbs didn't set the throttle plates all the way closed when they stamped the throttle lever onto the throttle shaft.

Engine is stock and runs really strong and responsive. Even with the stock 0.35 main jets though, judging by the plugs, it's still running lean. Would not have expected to go to a BIGGER jet over stock.

I'll order some new jets and when I pull the carbs off to change them, I'll take a close look at the gaps between the bores and throttle plates when the levers are all the way against the stops. Binding with the accelerator pump rod isn't right and neither is backing the speed screws all the way out. Might have to replace the throttle shaft/throttle lever assemblies.

I actually have a pair of brand new, in the box, made in UK, Stromberg 97s but I'd rather sell them and make the 81's work right.

10-30-2022, 02:44 PM	#19
SoCalCoupe Senior Member Join Date: Sep 2021 Location: Point Loma, San Diego, CA Posts: 431	Re: Where to start tuning a pair of 81s Started over and got myself sorted out with the idle mixture screws and settled on 7/8 of turn open on each. Got the throttles re-synched with the Uni-Syn. Don't think I have a vacuum leak; closing off either carb kills the engine. Still idling a little fast though even with the idle speed screws backed all the way out. When I apply pressure to the throttle lever it slows down the engine speed a bit and one of the accelerator pump rods still binds with the throttle lever. I'm thinking that whoever rebuilt the carbs didn't set the throttle plates all the way closed when they stamped the throttle lever onto the throttle shaft. Engine is stock and runs really strong and responsive. Even with the stock 0.35 main jets though, judging by the plugs, it's still running lean. Would not have expected to go to a BIGGER jet over stock. I'll order some new jets and when I pull the carbs off to change them, I'll take a close look at the gaps between the bores and throttle plates when the levers are all the way against the stops. Binding with the accelerator pump rod isn't right and neither is backing the speed screws all the way out. Might have to replace the throttle shaft/throttle lever assemblies. I actually have a pair of brand new, in the box, made in UK, Stromberg 97s but I'd rather sell them and make the 81's work right.