Another vacuum ?

[mvent]

Bought a vacuum gauge to help tune 1407 Edelbrock, started around 12 moving from 11-12, orange springs, adjusted up to 15 needle moving about 14.5-15. 440 automatic unknown cam have idle set to light brake pressure to hold in drive. Checked vacuum in drive drops to 10-11. Should spring choice be based on vacuum in drive or park?

 

[BSB67]

Neither.

 

[mvent]

Neither.

Neutral ?

 

[Jeff_383]

Drive it around with a gauge hooked up and able to read it inside the car. Look at the vacuum at a mild cruise. Whatever it may be, use a spring that is about 1" lower in vacuum. That's a good ballpark method.

 

[mvent]

Drive it around with a gauge hooked up and able to read it inside the car. Look at the vacuum at a mild cruise. Whatever it may be, use a spring that is about 1" lower in vacuum. That's a good ballpark method.

Thank you

 

[BSB67]

Drive it around with a gauge hooked up and able to read it inside the car. Look at the vacuum at a mild cruise. Whatever it may be, use a spring that is about 1" lower in vacuum. That's a good ballpark method.

Yes. This.

 

[Geoff 2]

Put the vac gauge way....
Loosen met rod piston covers, swivel slightly so that pistons are in view, but captured; tighten covers.
The pistons need to be down [ no movement ] in gear, at idle. Start with stiffest springs & keep going with spring selection until pistons stay down.

 

[mvent]

Put the vac gauge way....
Loosen met rod piston covers, swivel slightly so that pistons are in view, but captured; tighten covers.
The pistons need to be down [ no movement ] in gear, at idle. Start with stiffest springs & keep going with spring selection until pistons stay down.

Geoff, thanks for this I did it and ended up with blue 3” springs to keep pistons down in drive, cars definitely smells cleaner and smoother cruising on highway.
Thanks again.

 

[mvent]

BTW my vacuum reading now is steady at 15hg

 

[Jeff_383]

Honestly of you're at 10 to 11in gear and 15 in park, 3" springs seem way to low and will probably cause a lean spot in transition. But, if it works.

 

[mvent]

Honestly of you're at 10 to 11in gear and 15 in park, 3" springs seem way to low and will probably cause a lean spot in transition. But, if it works.

Agree, had yellow 4” in and they were moving, put orange 5” and they really jumped went to 3” and they stayed down. IDK