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Stromberg Tuning

Started by JohnTwist, August 09, 2020, 02:10:22 PM

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It's a couple of steps:

Set the timing at 32 degrees before top dead center, vacuum disconnected, at full mechanical advance (usually 3-4000 rpm).

Leave the throttle cable REALLY loose.

Tighten the air bleed screw until it's closed.  Leave it that way.

Start up the engine cold and quickly adjust the spring loaded screw on the linkage until the engine is running about 1600 rpm – that's fast idle.

As it warms, keep blipping the throttle and the idle will fall.

After the engine is fully warm (say, five minutes), then set the locknutted screw, the one on the carb body, so the idle speed is 800-900.  Make all future idle speed adjustments from the spring loaded screw.

Lift the air piston ever so slightly – one of three things will happen:

If it's already too lean, the rpm will fall off instantly

If it's too rich, the rpm will rise the higher you lift the air piston.

You are looking for the "sweet spot" – as you "just" disturb the position of the air piston, the rpm rises about 50-100 rpm and then falls away/

Make the mixture adjustments first in full turns, then in half turns, clockwise is rich.

Throughout this process, rev the engine after EVERY adjustment, just to clear it out – Vroom, vroom

You'll have to adjust the idle speed a couple of times as you get the correct mixture.

Finally, tighten the throttle cable with the engine idling, allowing 1/8" movement in the outer sheath at the firewall.Remember – the engine WILL NOT run correctly on the road, nor will it rev up correctly with the air cleaner off.  Reinstall the air cleaner before taking the car on the road.

John Twist, University Motors Online at
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids, MI  49506


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