light throttle stumbling

[pontiacgp]

A 6.5 opens with 6.5 of vacuum and not if the vacuum is under that and when the power valve is open the fuel mixture is enriched

 

[kingrichard]

putting in a higher power valve is to reduce the fuel so why did you fattened up the jets for more fuel?...what's the air fuel ratio?

6.5 pv opens before a 4.5 has nothing to do with reducing fuel.

You have that backwards. A 6.5 power valve opens at 6.5 inches of vacuum, whereas the 4.5 opens at 4.5 inches of vacuum. So as vacuum builds, the 4.5 will richen the circuit quicker than the 6.5 and, conversely, when you open the throttle and vacuum dies away, the 6.5 will close quicker than the 4.5.

you dont build up to it, you drop down to it.

 

[kingrichard]

A 6.5 opens with 6.5 of vacuum and not if the vacuum is under that and when the power valve is open the fuel mixture is enriched

6.5 opens at 6.5 or anything less.

 

[kingrichard]

4.5 pv was causing a lean stumble at light throttle cruising, and with those two light springs and timing all in at 1800 rpm even worse.

 

[pontiacgp]

do you have an 02 sensor with a gauge to measure air/fuel ratio?

 

[kingrichard]

do you have an 02 sensor with a gauge to measure air/fuel ratio?

no, its prolly a little fat but not to much.

 

[pontiacgp]

do you have an 02 sensor with a gauge to measure air/fuel ratio?

no, its prolly a little fat but not to much.

then how do you know

4.5 pv was causing a lean stumble at light throttle cruising

 

[kingrichard]

driving, checking plugs, seat of the pants feel, et and mph at track, like we did in the old days, 60s, 70s.

 

[kingrichard]

A 6.5 opens with 6.5 of vacuum and not if the vacuum is under that and when the power valve is open the fuel mixture is enriched

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