Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

LSX and decreased vaccum?

Thread Tools
 
Search this Thread
 
Old Jun 8, 2005 | 08:09 PM
  #1  
daryl2cb@yahoo.com's Avatar
Thread Starter
TECH Fanatic
iTrader: (2)
 
Joined: Jul 2004
Posts: 1,882
Likes: 0
From: Greensburg,PA
Default LSX and decreased vaccum?

I posted this over in external engine, yet no responces, so I will try here. I just installed the lsx manifold and I noticed that my vac guage now reads about 10hg in, instead of the usuall 20 some, is this normal, or have I spring a leak?
Reply
Old Jun 8, 2005 | 09:31 PM
  #2  
daryl2cb@yahoo.com's Avatar
Thread Starter
TECH Fanatic
iTrader: (2)
 
Joined: Jul 2004
Posts: 1,882
Likes: 0
From: Greensburg,PA
Default

anyone?
Reply
Old Jun 8, 2005 | 09:55 PM
  #3  
ArKay99's Avatar
TECH Regular
iTrader: (1)
 
Joined: Nov 2003
Posts: 490
Likes: 0
From: Washington Township, NJ
Default

I don't know about vacuum, but I changed my LS6 and ported TB for an LSX90 and Nick Williams TB. Scanned MAP stayed around 50-55kpa.
Reply
Old Jun 8, 2005 | 10:46 PM
  #4  
ChucksZ06's Avatar
TECH Resident
iTrader: (9)
 
Joined: Feb 2005
Posts: 976
Likes: 1
Default

I bet you have a leak. See if the manifold is warped.
Reply
Old Jun 8, 2005 | 11:34 PM
  #5  
TT_Vert's Avatar
TECH Fanatic
20 Year Member
iTrader: (12)
 
Joined: May 2004
Posts: 1,080
Likes: 0
From: Elgin, Illinois
Default

yeah no way that is right, loosing 10" of vacuum is huge..

dave
Reply
Old Jun 9, 2005 | 01:16 AM
  #6  
chpmnsws6's Avatar
TECH Addict
iTrader: (70)
 
Joined: Sep 2003
Posts: 2,525
Likes: 2
From: Springfield IL
Default

propane..... it'll find your leak
Reply
Old Jun 9, 2005 | 09:59 AM
  #7  
TT_Vert's Avatar
TECH Fanatic
20 Year Member
iTrader: (12)
 
Joined: May 2004
Posts: 1,080
Likes: 0
From: Elgin, Illinois
Default

out of curiousity, the idle will rise w/ propane? is it a signifigant rise?

Dave
Reply
Old Jun 9, 2005 | 01:35 PM
  #8  
HumpinSS's Avatar
FormerVendor
iTrader: (1)
 
Joined: Feb 2002
Posts: 3,059
Likes: 0
From: Waldorf, MD
Default

Did you hook p the vacuum hose for the AC controls
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Jun 9, 2005 | 03:25 PM
  #9  
daryl2cb@yahoo.com's Avatar
Thread Starter
TECH Fanatic
iTrader: (2)
 
Joined: Jul 2004
Posts: 1,882
Likes: 0
From: Greensburg,PA
Default

if you are refering to the t fitting of vac hoses that attaches to the rear right side(pass) of the manifold, then yes. I don't use the air, heater so I will double check to see if they are working properly,
Propane? never heard of that before, is it something a shop does, or can I do it at home here? Please explain
Reply
Old Jun 9, 2005 | 03:28 PM
  #10  
conan's Avatar
TECH Senior Member
20 Year Member
iTrader: (5)
 
Joined: May 2004
Posts: 6,492
Likes: 6
From: Back in the Burg
Default

You take a propane tourch and let the gas run out around you intake with the car running and if the rpms go up your intake isn't sealed on the heads.
Reply
Old Jun 9, 2005 | 03:41 PM
  #11  
Tranzor's Avatar
TECH Veteran
 
Joined: Aug 2003
Posts: 4,954
Likes: 1
From: Kent WA
Default

Did you make sure to replace the valley cover bolts with the button head ones that were included in the kit?
Reply
Old Jun 9, 2005 | 04:35 PM
  #12  
Beast96Z's Avatar
TECH Veteran
iTrader: (21)
 
Joined: Apr 2003
Posts: 4,049
Likes: 3
From: Shreveport, LA
Default

Sounds like you have a leak at the MAP sensor. That's usaully the first place to start. PM me your e-mail if you would like instructions on how to securly hold it in place.
Reply
Old Jun 10, 2005 | 08:28 AM
  #13  
daryl2cb@yahoo.com's Avatar
Thread Starter
TECH Fanatic
iTrader: (2)
 
Joined: Jul 2004
Posts: 1,882
Likes: 0
From: Greensburg,PA
Default

bingo, thanks brain, leak over the number 2 intake port, a little ether shot found it really quick, so I am going to pull it today, put new seals in again! hopefully this time is seals. Thanks for all the responces I'll keep you guys posted.
Reply
Old Jun 10, 2005 | 06:06 PM
  #14  
daryl2cb@yahoo.com's Avatar
Thread Starter
TECH Fanatic
iTrader: (2)
 
Joined: Jul 2004
Posts: 1,882
Likes: 0
From: Greensburg,PA
Default

well, I did not wait for the cam, I took it off today, and replaced with new seals, vac came up to 17hg in, so it improved 7in's I sprayed ether around everything and idle stayed constant, heater, and a/c are good, so I guess that is wrapped up, thanks guys and thanks LS1 tech, you guys solved another one.

I imagine the 3 in drop is due to the increased plenum of the intake, If anyone has any other reasons why they think is should still be normal let me know
Reply
Old Jun 10, 2005 | 06:30 PM
  #15  
TransAm52804's Avatar
TECH Enthusiast
 
Joined: May 2004
Posts: 593
Likes: 0
From: Davenport, Iowa
Default

Any way to fix a leak problem if, say, the manifold was warped besides buying a whole new one? I installed a used one, and I'm having the same problems for the most part, except on HPTuners, the graph showed my injectors giving no pulse at all. I have a thread in the external engine section if anyone wants to check it out.
Reply
Old Jun 10, 2005 | 09:21 PM
  #16  
02 Pewter LS1's Avatar
TECH Enthusiast
iTrader: (8)
 
Joined: Jul 2002
Posts: 554
Likes: 0
From: Melbourne Florida
Default

Just an idea to look at that my buddy and I noticed about our Fast intake install. The coolant crossover pipe in the front under the intake would keep the intake from laying all the way down? We installed a 78mm on his Z06 and a 90mm on mine in the past few days and they were both the same way. The instructions does not say anything about having to pry it forward and down. Wooden dowl rod and rubber mallet with a light touch took care of it and a screw driver. just thought I would see if you had the same problem.
Reply
Old Jun 12, 2005 | 10:37 PM
  #17  
daryl2cb@yahoo.com's Avatar
Thread Starter
TECH Fanatic
iTrader: (2)
 
Joined: Jul 2004
Posts: 1,882
Likes: 0
From: Greensburg,PA
Default

Yeah, although I just used a small dead weight hammer to GENTLY tap it down, I also was surprised that it did not clear the throttle body mount, also for any one else reading this, the instructions state to remove the upper plenum from the lower two sections that are preassembled at the factory to inspect the rope seal to make sure that it is seated properly, I called comp, and they said not to do this, just plain as day it is in there instructions, one reasons I hate to use to book, should have went with my instincts on this one as I was pulling apart the two halves, again, don't seperate the upper from the lower sections, if you do this you will have to buy a new rope seal, I learned the hard way. PS Unaffilated, please tell your sups to revise this in the instructions, it is way miss leading.
Reply




All times are GMT -5. The time now is 09:22 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE