Removing rear steam port block-offs???
01-16-2017, 10:47 PM
#3
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It seems the best way is to tap them out from the bottom when the heads are off.
I really didn't want to pull the heads, so I *carefully* and slowly drilled small holes in the plugs, using grease on the bit to keep the shavings out of the hole. I was able to pull them out with an EZ out when I got the hole deep enough.
You do run the risk of getting a bit of debris in the cooling passages this way.
I really didn't want to pull the heads, so I *carefully* and slowly drilled small holes in the plugs, using grease on the bit to keep the shavings out of the hole. I was able to pull them out with an EZ out when I got the hole deep enough.
You do run the risk of getting a bit of debris in the cooling passages this way.
01-20-2017, 03:54 AM
#7
I think the block offs were in place because of the LS6 or LS7 intake and fitment issues under the intake. They have since not used a rear crossover. The crossover helps remove trapped steam fron the heads and is supposed to move it to the highest point, being the Radiator to prevent hot spots. Trapped steam can cause major issues. Supposedly this is the reason why Cylinder 7 is a common failure point, just a Myth I think.
Last edited by 07NBSChevy; 01-20-2017 at 10:31 PM.
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01-20-2017, 05:14 AM
#8
GM isn't going to compromise the cooling system for a plastic intake. Stop assuming this. That's just plain stupid. If the rear ports were that important, GM simply would have routed the lines another way, not blocked them off completely.
01-20-2017, 10:05 PM
#9
Assuming what? I did not make am assumption? Why don't you explain since you seem to know the answer? Where did I say anything about GM compromising the coolant system, or saying that it will compromise the cooling system, even tho some people some say it does.
The 4 corner steam vent system did not fit under the intake, plain and simple, so they removed the rears, blocked them off, and just made the front a crossover. They have not used a rear crossover since then, which was 2001 or so. There are multiple sources for this. That may not be the only reason, but it was one of them. Which is why I said "I Think" at the very beginning of my post, since it may not have been the only reason.
Yes, GM could of routed it another way. Obviously over the intake since it will not fit under it, like I said, but they didn't think it was necessary.
Maybe you should research before making any comments.
http://www.corvetteforum.com/forums/...ports-fix.html Check out post #9
The 4 corner steam vent system did not fit under the intake, plain and simple, so they removed the rears, blocked them off, and just made the front a crossover. They have not used a rear crossover since then, which was 2001 or so. There are multiple sources for this. That may not be the only reason, but it was one of them. Which is why I said "I Think" at the very beginning of my post, since it may not have been the only reason.
Yes, GM could of routed it another way. Obviously over the intake since it will not fit under it, like I said, but they didn't think it was necessary.
Maybe you should research before making any comments.
http://www.corvetteforum.com/forums/...ports-fix.html Check out post #9
Last edited by 07NBSChevy; 01-20-2017 at 10:44 PM.
01-21-2017, 03:53 PM
#10
And "research" is a bit more involved than reading what one guy experienced.
Last edited by 8.Lug; 01-21-2017 at 04:10 PM.
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Dielectric (05-06-2020), JF74chevelle (06-18-2020)
01-21-2017, 04:16 PM
#12
But here's my assumption why GM removed them:
#1) The front ports were sufficient for clearing air pockets from the heads.
#2) Coolant flowing through those pipes is coolant that's bypassing the engine that could have been used to further cool the heads.
#1) The front ports were sufficient for clearing air pockets from the heads.
#2) Coolant flowing through those pipes is coolant that's bypassing the engine that could have been used to further cool the heads.
01-21-2017, 04:28 PM
#13
Dude. Right here. This is the assumption you made - that GM removed the crossover pipes because the intake was in the way. And not just one intake, but half a dozen different styles of intake over the years that GM made while somehow overlooking the fact the crossover pipes "did not fit under the intake plain and simple." No dude. The rear crossover pipes were removed FIRST because GM deemed them unnecessary, and then filled the space with the intake.
And "research" is a bit more involved than reading what one guy experienced.
And "research" is a bit more involved than reading what one guy experienced.
It is a fact that the existing design for the 4 corner steam vent system did not work due to clearance issues. GM had a mock up for the 4 corner steam vent system for the LS6 but decided not to manufacture it, cost was probably another factor. So they scraped the idea. Like I said, there may be other reason, but that is one reason. I said there are multiple sources I can post and there is a CAD design for it as well. They wanted to, decided the front was enough and done. I never said that was the only reason.
I worked at a Dealership long enough to know that GM would remove/scrap ideas because cost of redesigning it to make it work was not worth it if it was not 100% Necessary. They did not just remove it because they wanted to, especially since they had an existing design and it worked. They did not want to redesign it to work with the new engines. The LS6 Intake pretty much lays on the valley cover, would you rather them redesign the intake and raise it up a 1/2", which would change the runners and possibly change the performance aspect of the intake, just because the steam tubes? GM designed the LS6 intake, and probably knew that the steam vent tubes would have to be removed because of how low the intake sits, as well as did some testing and realized the front crossover was enough to keep steam pockets out of the heads. So they stopped using the 4 corner steam tubes ever since the LS6 was introduced. Do you think it was a coincidence that the 4 corner system was scraped ever since the LS6 came out in 2001, and not because their original design would not fit due to clearance issues?
Maybe I should rephrase my original post. "GM felt that is was unnecessary to redesign the 4 corner steam vent system to work with the newer engines due to clearance issues. Cost may have been another factor since the 4 corner system was not completely needed (In their minds at this point), so they just made the front a crossover and blocked off the rears which was sufficient enough (To Them). GM did design a 4 corner system for the newer engines but decided to scrap the idea, feeling that it was not 100% needed."
It would of been awesome for GM to design a 4 corner steam system that would go under the valley cover and have 4 slots where the tubes go through to connect to the heads to keep it hidden, but then again, cost vs it being 100% Necessary.
Last edited by 07NBSChevy; 01-21-2017 at 05:28 PM.
01-21-2017, 09:35 PM
#14
I honestly don't think 4 corner steam pipes is necessary, I've never had an issue and nobody I know has had an issue just running the fronts. The only way you will get a definitive answer is if one of GM's engineers comes in here and answers the question. Hey then again there's company's out there where you can waste $200-$300 on aftermarket 4 corner steam lines...
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James Martin (10-19-2020)
01-23-2017, 08:08 PM
#17
In the early stages of the LS design (1994) the heads were designed just like any other head, ambidextrous to either side. Originally, someone thought a 4 corner bleed off was a good idea. Of course the designs and purchasing of parts was made. So no use in throwing away purchased parts. They used them on the cars. When the truck engine and intake was designed, it began to delete the 4 corner idea.
As for the newer style using a plug. Well that idea was a mistake too. They leak. GM has a bulletin to remove them and use the blockoffs if a leak is discovered. Btw, its not a warranty coverage unless you're still within your powertrain warranty period.
I just left a dealer and now work at a peformance machine shop. So i have alot of GM history knowledge and been doing this for about 35 years.
As for the newer style using a plug. Well that idea was a mistake too. They leak. GM has a bulletin to remove them and use the blockoffs if a leak is discovered. Btw, its not a warranty coverage unless you're still within your powertrain warranty period.
I just left a dealer and now work at a peformance machine shop. So i have alot of GM history knowledge and been doing this for about 35 years.