CRG Discussion Forum
Welcome, Guest. Please login or register.
Did you miss your activation email?
September 21, 2014, 03:12:40 PM

Login with username, password and session length
Search:     Advanced search
Welcome to the CRG Discussion Forum!
Forum registration problems: Make sure you enter your email correctly and you check your spam box first. *Then* email KurtS2@gmail for help.
104630 Posts in 12242 Topics by 4719 Members
Latest Member: Baconcks
* Home Help Search Login Register
+  CRG Discussion Forum
|-+  Camaro Research Group Discussion
| |-+  Maintenance
| | |-+  low vacuum at idle
« previous next »
Pages: [1] Print
Author Topic: low vacuum at idle  (Read 1676 times)
william1
Member
***
Posts: 43


View Profile
« on: August 29, 2009, 01:04:21 PM »

Where do I start, after getting heads reworked on my 302ci 69 z and reinstalling I now have low vacuum at idle, this engine has modifications to it pistons 12/1, cam not sure but not stock by any means manifold, 750 dual pumper 4779-s, headers, HEI
I have checked for leaks and canít find any, but hereís the interesting part, I get a head brake pedal at idle, Iím checking the booster for leaks.
We used the valve adjustment  26/26 90 degrees before and after TDC , instead of the standard 30/30 at TDC, advance 33, could I have created a late valve lag to the point I have low vacuum, itís like 6 at idle , also I have very quick hesitation when I get on the throttle.
Logged
JohnZ
CRG Member
*****
Posts: 4103


View Profile Email
« Reply #1 on: August 29, 2009, 08:35:06 PM »

Where do I start, after getting heads reworked on my 302ci 69 z and reinstalling I now have low vacuum at idle, this engine has modifications to it pistons 12/1, cam not sure but not stock by any means
We used the valve adjustment  26/26 90 degrees before and after TDC , instead of the standard 30/30 at TDC, advance 33, could I have created a late valve lag to the point I have low vacuum, it’s like 6 at idle , also I have very quick hesitation when I get on the throttle.


The procedure outlined in my "30-30" cam lash adjustment procedure (.026" cold, using the indexing procedure exactly as described) is ONLY FOR THE FACTORY '30-30" CAM, and will produce 9"-11" Hg. of manifold vacuum at a 900 rpm idle. If you don't know what aftermarket cam is in it, you need to find out and follow the cam manufacturer's instructions on the cam card for hot or cold valve lash.
Logged

'69 Z/28
Fathom Green
CRG
william1
Member
***
Posts: 43


View Profile
« Reply #2 on: September 02, 2009, 08:29:53 AM »

 thanks johnz, went back to the old school method vacum now up, but short of trying to put a degree wheel on this thing, this will have to do for the moment.
Logged
L78 steve
Member
***
Posts: 433



View Profile Email
« Reply #3 on: September 16, 2009, 11:59:22 AM »

Check your booster.I just had that happen on a orig. 69. The idle was so weak turning the steering wheel would stall the engine,not enough power for the P/S. Hard pedal at idle also.
Logged

69 Z/28 Dover White X33,ZL2,PS,M20,Std.int.04C
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C
Pages: [1] Print 
« previous next »
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!
Page created in 0.071 seconds with 17 queries.