6.0 Low vacuum readings
Thread Starter
Teching In
Joined: Apr 2023
Posts: 19
Likes: 0
From: Missouri
*update* *UPDATE*
Hey all, just wanted to provide a follow-up because I'm still having problems. Last week, we came to the conclusion that I had a few bad vacuum leaks with my existing intake. I ordered a used OEM LS2 intake, throttle body, and injectors that came with it and installed that. Went to start it up with every port on the new intake capped (Brakes and PCV) just so there are no vacuum leaks. It ran better, a lot better but while watching the fuel table on my Terminator X MAX it shows that at idle I'm pulling 90-91 kpa of vacuum. That is extremely high. I then switched from using the internal 1 bar sensor to using the GM one mounted on the intake in hopes that something would change. Nothing changed. The engine has a serious loss of power. I drove it and it sounds like it wants to take a breath before getting up in rpms. I pulled the entire front of the motor off to check my cam timing and that was indeed correct. Checked for anything messed up in my valve train (Rockers, pushrod length, and not bent). Today I'm going to conduct a leak test to see if I'm losing anything there. I'll include my tune below because I'm not ruling that out of the equation. This is my first time using the Holley Terminator X so I'm not the most confident in using it. If anyone needs more information or has any thoughts don't hesitate to ask. Thanks, Luke.
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
I would degree your cam to make sure everything is correct. Sounds the cam could be off it has happened more than you would think. Ask Darth he had a cam way off from specs.
Also make sure your tune is correct. I have never used Holly but there are a lot of people on here that does. Post in the tune section.
Also make sure your tune is correct. I have never used Holly but there are a lot of people on here that does. Post in the tune section.
TECH Fanatic
Joined: Jan 2009
Posts: 1,065
Likes: 476
From: Bostwick, GA.
The cause.... 
He put a straight edge across a set from 1 head. 4 were WAY short!
He found a set locally and put them on .
WALA! runs well!
My thinking is those 4 springs were never heat treated and were collapsed when the engine was first started.
Thread Starter
Teching In
Joined: Apr 2023
Posts: 19
Likes: 0
From: Missouri
I did a lot of fone conversations with him and finally had him pull the springs. When he told me he could compress the springs with his thumb, it became clear there was an issue with 4 valve springs.
He put a straight edge across a set from 1 head. 4 were WAY short!
He found a set locally and put them on .
WALA! runs well!
My thinking is those 4 springs were never heat treated and were collapsed when the engine was first started.
He put a straight edge across a set from 1 head. 4 were WAY short!
He found a set locally and put them on .
WALA! runs well!
My thinking is those 4 springs were never heat treated and were collapsed when the engine was first started.
don’t buy junk springs. Sorry I forgot to post and update my problems. Been quite busy lately.
I think he mentioned that the cam came in kit form with the springs, and push rods as well. If the springs are JUNK... makes you wonder what the quality of the cam is like. Junk springs probably means a junk cam as well. He indicates a "SS2".. Most likely a white box CHINA knock off cam... There was a post here not long ago about those... If it were mine, I'd be pulling the cam and replacing it with a known good cam from Summit, BTR, or Texas Speed, Crane, Comp-anyone with a good reputation. I'd also be replacing all the springs with something like GENUINE Pac's... If he has had 4 springs fail just from start up and idle time-would you trust any of the other 12? Not me.
Thread Starter
Teching In
Joined: Apr 2023
Posts: 19
Likes: 0
From: Missouri
I think he mentioned that the cam came in kit form with the springs, and push rods as well. If the springs are JUNK... makes you wonder what the quality of the cam is like. Junk springs probably means a junk cam as well. He indicates a "SS2".. Most likely a white box CHINA knock off cam... There was a post here not long ago about those... If it were mine, I'd be pulling the cam and replacing it with a known good cam from Summit, BTR, or Texas Speed, Crane, Comp-anyone with a good reputation. I'd also be replacing all the springs with something like GENUINE Pac's... If he has had 4 springs fail just from start up and idle time-would you trust any of the other 12? Not me.
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