Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!

Valve overlap and Manifold vacuum

Thread Tools
 
Search this Thread
 
Old 10-14-2001, 06:27 PM
  #1  
Member
Thread Starter
 
RyanSS's Avatar
 
Join Date: Jan 2001
Location: Abilene/Lubbock, TX
Posts: 389
Likes: 0
Received 0 Likes on 0 Posts
Valve overlap and Manifold vacuum

More valve overlap=less vacuum right?
Would around 70 or so overlap provide over 14" of vacuum? can anyone elaborate on the relationship? and what vacuum is required to operate power accessories?

------------------
89 RS parts car
Daily driver 91 RS auto LO3 70k, 14x3 K&N Open element, cat-back delete, Richmond 3.42's, Zexel Torsion posi.
Coming soon: 350, headers, loudmouth exhaust, gutted cat.
Old 10-16-2001, 10:02 PM
  #2  
Member
Thread Starter
 
RyanSS's Avatar
 
Join Date: Jan 2001
Location: Abilene/Lubbock, TX
Posts: 389
Likes: 0
Received 0 Likes on 0 Posts
ttt

------------------
89 RS parts car
Daily driver 91 RS auto LO3 70k, 14x3 K&N Open element, cat-back delete, Richmond 3.42's, Zexel Torsion posi.
Coming soon: 350, headers, loudmouth exhaust, gutted cat.
Old 10-17-2001, 02:27 AM
  #3  
Supreme Member

 
JoelOl75's Avatar
 
Join Date: Jan 2001
Location: PA
Posts: 1,978
Likes: 0
Received 0 Likes on 0 Posts
Car: 88 Firebird WS6
Engine: 350 TPI
Transmission: T56
Axle/Gears: 3.42
Duration also plays a role, so overlap isn't the only factor. More duration with less overlap could net less vacuum.

Also the same cam installed in a motor with more cubes will have more vacuum.

And, whether the cam is installed straight up or advanced changes vacuum also...
Old 10-19-2001, 12:26 AM
  #4  
Member
Thread Starter
 
RyanSS's Avatar
 
Join Date: Jan 2001
Location: Abilene/Lubbock, TX
Posts: 389
Likes: 0
Received 0 Likes on 0 Posts
Can anyone give some examples, like give your engine specs, vacuum numbers, and streetability?

------------------
89 RS parts car
Daily driver 91 RS auto LO3 70k, 14x3 K&N Open element, cat-back delete, Richmond 3.42's, Zexel Torsion posi.
Coming soon: 350, headers, loudmouth exhaust, gutted cat.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
deracer
Camaros for Sale
3
04-11-2016 12:04 AM
db057
TBI
13
09-04-2015 07:57 AM
Bubbajones_ya
TBI
2
08-28-2015 02:17 AM
lakeffect2
Cooling
11
08-23-2015 08:44 AM



Quick Reply: Valve overlap and Manifold vacuum



All times are GMT -5. The time now is 02:21 AM.