1955 engine issue accelerating

[NickIt]

The engine is a 292 three speed auto with a teapot carb...everything goes perfect speeding up till 2nd gear but when the gear shifts in 3rd gear the engine starts to stall and the same happens going uphill...
Can anyone help me?
Nick

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[Rod Bender]

The engine is a 292 three speed auto with a teapot carb...everything goes perfect speeding up till 2nd gear but when the gear shifts in 3rd gear the engine starts to stall and the same happens going uphill...
Can anyone help me?
Nick

Check your vacuum advance for ruptured diaphragm.

 

[NickIt]

Check your vacuum advance for ruptured diaphragm.

I thought it might be the cause but I didn't find any vacuum in internet...

 

[doug7740]

There are two vacuum passages that supply vacuum to the distributor vacuum advance. The primary passage is at the venture (that’s why you have to set the base ignition timing with the distributor vacuum line disconnected) and the other passage is at the throttle plate. At idle, when the throttle plate is closed, venture vacuum is higher and it raises the check ball in the vertical passage sealing off the than the passage to the throttle plate. This prevents venture vacuum from escaping through the throttle plate passage.

All of the vacuum to the distributor vacuum advance passes through the spark control valve. When accelerating and the vacuum at the throttle plate is high, the spark control valve closes the passage from the throttle plate to the distributor vacuum advance preventing too much advance or a controlled amount of advance. So, at idle next to nothing is being sent to the distributor advance diaphragm. The Holley manuals provide a chart with typical vacuum and advance figures under different throttle positions. The chart shows the advance starting to move at .16 inches, the decimal point is correct, .16 inches of vacuum at approximately 600 rpm. Full advance is reached at less than 3.0 inches of vacuum.

doug7740
1955 Thunderbird Blue