#7 Piston Failure FIX !!!
#7 Piston Failure FIX !!! --------------------------------------------------------------------------
I found this tip reading Will Handzel's book How to Build High-Performance Chevy LS1/LS6 V-8's.
When GM started using the LS6 Intake manifold they omitted the rear steam vent tubes on rear of heads and used only a front vent tube version because of clearence issues with the lower floor of the LS6 manifold. Some road racers say blocking off the rear steam ports will cause detonation and damage the #7 piston. Here is the cure and I quote from book:
"TIP: Some road racers have been using the pre-LS6 steam tubes underneath the LS6 intake to improve cooling in cylinder number 7 (they previously had detonation problems in that hole). While the pre LS6 rear steam version was not used on factory LS6's, they will fit under the intake by slightly grinding down some of the stiffening ribs on the bottom side of the intake. Some racers just install the steam tube component and, during rebuilds, find some small indentions where the ribs come in contact with it and grind away for clearence."
Can we use the pre LS6 vent tube with the FAST intake?
I found this tip reading Will Handzel's book How to Build High-Performance Chevy LS1/LS6 V-8's.
When GM started using the LS6 Intake manifold they omitted the rear steam vent tubes on rear of heads and used only a front vent tube version because of clearence issues with the lower floor of the LS6 manifold. Some road racers say blocking off the rear steam ports will cause detonation and damage the #7 piston. Here is the cure and I quote from book:
"TIP: Some road racers have been using the pre-LS6 steam tubes underneath the LS6 intake to improve cooling in cylinder number 7 (they previously had detonation problems in that hole). While the pre LS6 rear steam version was not used on factory LS6's, they will fit under the intake by slightly grinding down some of the stiffening ribs on the bottom side of the intake. Some racers just install the steam tube component and, during rebuilds, find some small indentions where the ribs come in contact with it and grind away for clearence."
Can we use the pre LS6 vent tube with the FAST intake?
Last edited by gollum; Jun 8, 2006 at 08:37 AM.
I bought a motor that had a D1SC on it and then a 76mm STS system, when I tore it down #7 was missing some of the top compression ring... thanks for the info 
The motor only had about 10K on it too.
I definately think it would have made a difference on his car, my car is N/A however and the motor is already in otherwise I would have put it in there for the piece of mind.
The motor only had about 10K on it too.I definately think it would have made a difference on his car, my car is N/A however and the motor is already in otherwise I would have put it in there for the piece of mind.
Just wanted to throw this out there..I have seen 3 LS1 cars with a random misfire on #7, one with a dead miss, with the fuel system being a "dead head" system(no return to tank)...I tore down the fuel rails on all 3 cars....all cars were FULL of trash in the rear drivers side of the rail(#7)..all 3 cars were fixed with a cleaning and clean injectors. They picked up SERIOUS amounts of power.
Maybe look at this in the future.
David
Maybe look at this in the future.
David
Originally Posted by FASTFATBOY
Just wanted to throw this out there..I have seen 3 LS1 cars with a random misfire on #7, one with a dead miss, with the fuel system being a "dead head" system(no return to tank)...I tore down the fuel rails on all 3 cars....all cars were FULL of trash in the rear drivers side of the rail(#7)..all 3 cars were fixed with a cleaning and clean injectors. They picked up SERIOUS amounts of power.
Maybe look at this in the future.
David
Maybe look at this in the future.
David
Originally Posted by Zymosis
What did you use to clean injectors/how was it done?
I sent one set to get cleaned locally, bought used injectors the other two times, it was cheaper.
David
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
That's definitely a good thing to keep an eye on but I think part of the #7 failures has to do with the cooling system. I've got a Silverado SS sittin' at my shop with 18,000 miles and a spotless fuel system with the #7 piston blowed the f#@k up.
My 10k mile 04 Silverado is in the dealer now with a blown No. 7. It was showing misfire codes on and off for about 6 months and using oil. I guess a D1 at 11 psi on a stock motor can do that. 
Originally Posted by FASTFATBOY
Just wanted to throw this out there..I have seen 3 LS1 cars with a random misfire on #7, one with a dead miss, with the fuel system being a "dead head" system(no return to tank)...I tore down the fuel rails on all 3 cars....all cars were FULL of trash in the rear drivers side of the rail(#7)..all 3 cars were fixed with a cleaning and clean injectors. They picked up SERIOUS amounts of power.
Maybe look at this in the future.
David
Maybe look at this in the future.
David
We are having problems with #7. The shop says there is no compression there and the car smokes like a chimney. The shop wanted $3000+ to take the engine out and then whatever the shop they sent it to would charge for the machine work, THEN MORE money to put the engine back in! I can't afford that!
So any suggestions what should we do. This problem with the #7 cylinder......should we replace the block? What causes it, I see some say, dirty injectors, air inequalities, ect. Our car has a Vortech supercharger, a Bullet racing cam, 36# injectors, and a whole mess of other things. I would really like to get it running.
So any suggestions what should we do. This problem with the #7 cylinder......should we replace the block? What causes it, I see some say, dirty injectors, air inequalities, ect. Our car has a Vortech supercharger, a Bullet racing cam, 36# injectors, and a whole mess of other things. I would really like to get it running.
TECH Apprentice
Joined: Oct 2005
Posts: 320
Likes: 0
From: Norwalk, CT
Has anyone contacted a dealership, or a dealer tech? I bought a used 6.0 LQ4 w/ 10k on it. Everything looked MINT...until the heads came off 
#7 was scored and pitted. Delivered the motor to a sponsor to check it out (now going 408
) and they said GM was replacing a **** load of motors due to
an oiling issue. I would assume the lack of oil was allowing #7 to get tight and break rings. I'm sure the cooling/clogged injector thing doesnt help either.
What do you guys think
#7 was scored and pitted. Delivered the motor to a sponsor to check it out (now going 408
) and they said GM was replacing a **** load of motors due to an oiling issue. I would assume the lack of oil was allowing #7 to get tight and break rings. I'm sure the cooling/clogged injector thing doesnt help either.
What do you guys think
Originally Posted by Mrs. Ronin
We are having problems with #7. The shop says there is no compression there and the car smokes like a chimney. The shop wanted $3000+ to take the engine out and then whatever the shop they sent it to would charge for the machine work, THEN MORE money to put the engine back in! I can't afford that!
So any suggestions what should we do. This problem with the #7 cylinder......should we replace the block? What causes it, I see some say, dirty injectors, air inequalities, ect. Our car has a Vortech supercharger, a Bullet racing cam, 36# injectors, and a whole mess of other things. I would really like to get it running.
So any suggestions what should we do. This problem with the #7 cylinder......should we replace the block? What causes it, I see some say, dirty injectors, air inequalities, ect. Our car has a Vortech supercharger, a Bullet racing cam, 36# injectors, and a whole mess of other things. I would really like to get it running.
You can get a brand new 346/347 forged shortblock from a sponsor for under $3000. Look at texas-speed, SDPC, FFHP, etc...they all make some stout short blocks.
Originally Posted by mr2guru
and flow injectors putting the strongest on #7.
Originally Posted by Shinerbock07
how do i clean m fuel rails and injectors????