Poor vacuum
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Banned
Joined: Jan 2008
Posts: 547
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From: Europe->Poland->Warsaw
Car: 1988 Pontiac Firebird
Engine: 305 LT1 intake&heads
Transmission: TH700r4
Axle/Gears: 3.73 10bolt GM
Poor vacuum
my setup is 383, 165cc heads, HSR, CS XR276HR-12 cam and my car is producing only 66 kPa (about -0,4 bar) 
is there any way to make it better and go to about -0,6-0,7 ??
best regards
is there any way to make it better and go to about -0,6-0,7 ??best regards
Thread Starter
Banned
Joined: Jan 2008
Posts: 547
Likes: 0
From: Europe->Poland->Warsaw
Car: 1988 Pontiac Firebird
Engine: 305 LT1 intake&heads
Transmission: TH700r4
Axle/Gears: 3.73 10bolt GM
Re: Poor vacuum
oh i forgot add this information
0 bar = 100 kPa = 29 mercury (inHg) (that is how Megasquirt calculate pressure/vacuum)
i have: 66 kPa = -0,4 bar = 11 inHq
i need: 40 kPa = -0,7 bar = 20 inHg
0 bar = 100 kPa = 29 mercury (inHg) (that is how Megasquirt calculate pressure/vacuum)
i have: 66 kPa = -0,4 bar = 11 inHq
i need: 40 kPa = -0,7 bar = 20 inHg
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Supreme Member
Joined: Sep 2002
Posts: 9,192
Likes: 19
From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: Poor vacuum
changing the timing helped me when I swapped to a carbed 350 - of course after advancing the timing I had to back off the carb adjustments again to get a decent idle, but for whatever reason, it raised my vacuum plenty.
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