how much vacuum is too much vacuum?
07-29-2013, 02:11 PM
#1
Supreme Member
Thread Starter
iTrader: (6)
Join Date: Aug 2009
Location: Elwood, IN
Posts: 3,670
Likes: 0
Received 3 Likes
on
3 Posts
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
how much vacuum is too much vacuum?
I was going over my adjustments today and when I have a vacuum gauge hooked up to my pcv port on my carb, I'm pulling a steady 22-23 HGS of vacuum at 750 rpm on a v6 tach. Good? Bad? I tried setting my timing by vacuum but it didn't look to good lol.
07-29-2013, 02:51 PM
#2
Member
Join Date: Apr 2002
Location: Staten Island, NY
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
Re: how much vacuum is too much vacuum?
That's fine. A stock cam is always going to have high vacuum at idle.
Why are you setting your timing according to vacuum? Thats not a good idea!
With that small camshaft it doesn't need a lot of timing down low. Just order the spring kit for an hei and put the light or medium springs in it and set timing at between 32 - 34 at 3500 rpm. Wherever it falls at idle doesn't really matter.
Why are you setting your timing according to vacuum? Thats not a good idea!
With that small camshaft it doesn't need a lot of timing down low. Just order the spring kit for an hei and put the light or medium springs in it and set timing at between 32 - 34 at 3500 rpm. Wherever it falls at idle doesn't really matter.
07-29-2013, 03:26 PM
#3
Member
Join Date: Jun 2001
Location: new york , n.y. , USA
Posts: 397
Likes: 0
Received 10 Likes
on
10 Posts
Car: klowny1969 <-youtube 4 3rd gen vids
Engine: subscribe to klowny1969 on youtube!
Transmission: subscribe to my channel on youtube
Re: how much vacuum is too much vacuum?
stock cam thats about right...HOWEVER...alot of people dont know that in the high performance world..if you have a very lumpy cam and ur vacuum is way too high..that could mean that either the lobes have been rounded out or something is binding or not working right in your valvetrain...so too much vacuum can also be a bad thing..it all depends..
07-29-2013, 05:18 PM
#4
Supreme Member
Thread Starter
iTrader: (6)
Join Date: Aug 2009
Location: Elwood, IN
Posts: 3,670
Likes: 0
Received 3 Likes
on
3 Posts
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: how much vacuum is too much vacuum?
That's fine. A stock cam is always going to have high vacuum at idle.
Why are you setting your timing according to vacuum? Thats not a good idea!
With that small camshaft it doesn't need a lot of timing down low. Just order the spring kit for an hei and put the light or medium springs in it and set timing at between 32 - 34 at 3500 rpm. Wherever it falls at idle doesn't really matter.
Why are you setting your timing according to vacuum? Thats not a good idea!
With that small camshaft it doesn't need a lot of timing down low. Just order the spring kit for an hei and put the light or medium springs in it and set timing at between 32 - 34 at 3500 rpm. Wherever it falls at idle doesn't really matter.
07-29-2013, 05:40 PM
#5
Member
Join Date: Apr 2002
Location: Staten Island, NY
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
Re: how much vacuum is too much vacuum?
you shouldn't be setting idle timing for best idle either unless you can also properly adjust total timing also. Just set it around 12 - 14 at idle or do what I said in my last post.
Thread
Thread Starter
Forum
Replies
Last Post
Pac J
Tech / General Engine
3
05-17-2020 10:44 AM
HoosierinWA
Tech / General Engine
5
10-07-2015 10:15 AM
