Problems, problems, problems......
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
Here is what I borrowed from someone else in regards to the "holes" in the bottom of the manifold. This is a modification done when the manifold is ported to ensure proper BLM's/Idle etc as it is a manufacturing problem. This came from a very highly respected head porter.
""Also, another thing that's worth mentioning that some still don't know about.... "IF" your interested in getting the nicest possible idle out of a cammed LT-X set-up (if you haven't done it already).......Next time you have the LT intake manifold off the car.....flip it over, and remove the bottom (metal cover with the 4 bolts)......then remove ALL of the large Allen type pipe plugs that are under it......By removing the large pipe plugs, you'll gain access to the individual IAC port holes that go out to "each" manifold runner (there are two under "each" plug)..........From the factory, these holes are not perfectly even (size wise) from hole to hole like they should be.....And (very commonly) one of them is usually REALLY bad (small)......Many of them also have thick aluminum burrs partially blocking the passages due to a sloppy factory drill job......Take your largest hole out of the bunch (verified by sliding drill bits in them), then once you get the drill bit for the largest one....Drill the rest out to match.....Then RE-install your pipe plugs with some permatex #2 (the non-hardening sealant), and ofcourse loc-tite your metal splash cover back on.........This process also made a noticeable difference on mine, and is something that I always do on ALL of the LT-X engine's that I do Heads & Cam packages on.......The end-result is Not as drastic as the IAC hole being sized properly, but it's a nice difference none the less."
""Also, another thing that's worth mentioning that some still don't know about.... "IF" your interested in getting the nicest possible idle out of a cammed LT-X set-up (if you haven't done it already).......Next time you have the LT intake manifold off the car.....flip it over, and remove the bottom (metal cover with the 4 bolts)......then remove ALL of the large Allen type pipe plugs that are under it......By removing the large pipe plugs, you'll gain access to the individual IAC port holes that go out to "each" manifold runner (there are two under "each" plug)..........From the factory, these holes are not perfectly even (size wise) from hole to hole like they should be.....And (very commonly) one of them is usually REALLY bad (small)......Many of them also have thick aluminum burrs partially blocking the passages due to a sloppy factory drill job......Take your largest hole out of the bunch (verified by sliding drill bits in them), then once you get the drill bit for the largest one....Drill the rest out to match.....Then RE-install your pipe plugs with some permatex #2 (the non-hardening sealant), and ofcourse loc-tite your metal splash cover back on.........This process also made a noticeable difference on mine, and is something that I always do on ALL of the LT-X engine's that I do Heads & Cam packages on.......The end-result is Not as drastic as the IAC hole being sized properly, but it's a nice difference none the less."
1 - 1.05
8 - 0.96
4 - 0.97
3 - 0.96
6 - 1.02
5 - 1.01
7 - 0.98
2 - 1.05
Not saying that making all the holes the same size is wrong, just that there are more "moving parts" than many may realize.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
If that was directed at me I just want to say it is my professional opinion like I stated.No one has to believe me but I do this for aliving & only post comments that I know alot about subject from experience.But if something works for you post what you recommend too.Remember opinions are like assh--es everyone has one but the only difference is it seems on this forum there is alot of valuable opinons.No harm officer,check my posts, I do know alot but also don't know everything thats why I'm here.You seem to know alot about corvettes & I am impressed with yours & everyones knowledge
Ah, please, guys, let it go.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade!!!
Le Mans Master
Joined: Feb 1999
Posts: 9,916
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
FWIW GM did that on purpose. Also keep in mind that the programming in the PCM reflects this as well. There is a table called "Cylinder Fuel Balance at idle" and one for off-idle. >1 = more fuel, < 1 subtracts fuel. These are the idle values for a stock LT4...
1 - 1.05
8 - 0.96
4 - 0.97
3 - 0.96
6 - 1.02
5 - 1.01
7 - 0.98
2 - 1.05
Not saying that making all the holes the same size is wrong, just that there are more "moving parts" than many may realize.
1 - 1.05
8 - 0.96
4 - 0.97
3 - 0.96
6 - 1.02
5 - 1.01
7 - 0.98
2 - 1.05
Not saying that making all the holes the same size is wrong, just that there are more "moving parts" than many may realize.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
FWIW GM did that on purpose. Also keep in mind that the programming in the PCM reflects this as well. There is a table called "Cylinder Fuel Balance at idle" and one for off-idle. >1 = more fuel, < 1 subtracts fuel. These are the idle values for a stock LT4...
1 - 1.05
8 - 0.96
4 - 0.97
3 - 0.96
6 - 1.02
5 - 1.01
7 - 0.98
2 - 1.05
Not saying that making all the holes the same size is wrong, just that there are more "moving parts" than many may realize.
1 - 1.05
8 - 0.96
4 - 0.97
3 - 0.96
6 - 1.02
5 - 1.01
7 - 0.98
2 - 1.05
Not saying that making all the holes the same size is wrong, just that there are more "moving parts" than many may realize.
The only post I've come across, before these, was a guy who posted about finding carbon partially blocking at least one of his. That cleaning away the carbon improved his idle.
Steve, what size do you make the modded holes?
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
That's interesting information. Seems that Mike, from his previous post, has the #1 smaller than the others but your listing shows it to be one of two largest. And Steve says he's on reliable info to equalize them all and that he always does.
The only post I've come across, before these, was a guy who posted about finding carbon partially blocking at least one of his. That cleaning away the carbon improved his idle.
Steve, what size do you make the modded holes?
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
The only post I've come across, before these, was a guy who posted about finding carbon partially blocking at least one of his. That cleaning away the carbon improved his idle.
Steve, what size do you make the modded holes?
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
In an ideal world, airflow into each cylinder would be equal. However in the real world it's not. Between programming and idle air bleed holes, GM made the attempt to balance things.
Le Mans Master
Joined: Feb 1999
Posts: 9,916
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
That's interesting information. Seems that Mike, from his previous post, has the #1 smaller than the others but your listing shows it to be one of two largest. And Steve says he's on reliable info to equalize them all and that he always does.
The only post I've come across, before these, was a guy who posted about finding carbon partially blocking at least one of his. That cleaning away the carbon improved his idle.
Steve, what size do you make the modded holes?
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
The only post I've come across, before these, was a guy who posted about finding carbon partially blocking at least one of his. That cleaning away the carbon improved his idle.
Steve, what size do you make the modded holes?
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
Burning Brakes
Joined: Apr 2006
Posts: 1,043
Likes: 3
From: Toledo Ohio
I just started reading this thread yesterday and finished it up today. I kept waiting for the happy ending. I guess it's going to take a few more posts. 
I'm pulling for ya Weav. This has certainly been a painstaking adventure for you and I commend you for your persistence. This thread has been a great read and there's a wealth of knowledge here. I have no doubt that with the help of the forum, you will have this problem solved soon. Keep your chin up!
I'm pulling for ya Weav. This has certainly been a painstaking adventure for you and I commend you for your persistence. This thread has been a great read and there's a wealth of knowledge here. I have no doubt that with the help of the forum, you will have this problem solved soon. Keep your chin up!
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
I think the new lifers will be here today or tomorrow.
Is it mandatory to soak them in oil overnight as some have done or would a good dip in a container of oil do just as well? Frankly, I can't see how an overnight soaking will let anymore oil in the lifter than a quick dip would. I thought I'd ask though.
Is it mandatory to soak them in oil overnight as some have done or would a good dip in a container of oil do just as well? Frankly, I can't see how an overnight soaking will let anymore oil in the lifter than a quick dip would. I thought I'd ask though.
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Le Mans Master
Joined: Feb 1999
Posts: 9,916
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
I think the new lifers will be here today or tomorrow.
Is it mandatory to soak them in oil overnight as some have done or would a good dip in a container of oil do just as well? Frankly, I can't see how an overnight soaking will let anymore oil in the lifter than a quick dip would. I thought I'd ask though.
Is it mandatory to soak them in oil overnight as some have done or would a good dip in a container of oil do just as well? Frankly, I can't see how an overnight soaking will let anymore oil in the lifter than a quick dip would. I thought I'd ask though.
Use Synthetic as it is a superior oil, J/K.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
The lifters came today but I'm still at a stand still until the GM guide plates arrive. I took a couple of comparison pictures of the GMPP next to the LS7. There is a noticeable difference in the depth of the push rod pocket. Other than that they appear identical. The LS7's are nowhere as deep as the GMPP ones. I guess this is because of the stiffer spring inside the lifter. Hopefully if the lifters were collapsing this stronger spring will do a better job at holding the pressure of the springs I have. I'm going to use the one cylinder at the time method of adjusting preload. I'll set it at 3/4 turn past zero lash.
The LS7 lifter is on the right. I know it's hard to tell from the phots but the difference is there.
Oh, and since I have to wait on the plates I decided to soak the lifters. It must help because air bubbles came up for quite some time after submersing them in oil.
The LS7 lifter is on the right. I know it's hard to tell from the phots but the difference is there.
Oh, and since I have to wait on the plates I decided to soak the lifters. It must help because air bubbles came up for quite some time after submersing them in oil.
Last edited by Weav's Vet; Dec 22, 2013 at 01:22 PM.
Safety Car
Joined: Aug 2008
Posts: 4,344
Likes: 48
From: San Marcos CA
submerging lifters in an oil bath is an absolute mess. I pre-lube mine with one of those old fashioned hand pumpable oil cans with the metal tip at the end of the spout. you pump it in there like you would inflating a basketball. when the plunger tops out and oil bleeds back out of the hole on the side, you're done.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I don't know about the lifters you received but some lifters come from the factory with a thick grease in/on the roller bearings and on the exterior of the lifter body. This grease should always be WASHED AWAY with some type of solvent, like mineral spirits.
It's used at the factory during assembly and helps protect them while sitting on the shelf, waiting to be sold, but can inhibit oil flow to the roller bearings once the engine fires.
After cleaning off the grease, you then let them dry or blow dry them and THEN submerge them in oil; something like 30W. Turn the rollers repeatedly with the lifter(s) in the oil to make sure all the bearings receive a good oil coating.
As far as primeing them, there are differing views on that (what else is new?): Comp says NOT to prime them, that soaking is all they need. In fact, Comp says it's undesirable to prime them. Some guys insist on using an oil can or a pushrod to prime the lifters, but Comp has a different view. I never prime mine.
Trick, too, is not to let the engine sit for a prolonged period of time before it gets fired. I always use an oil priming tool to re-pressurize/re-fill the oil galleries before bolting down the intake.
Hope this helps.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
It's used at the factory during assembly and helps protect them while sitting on the shelf, waiting to be sold, but can inhibit oil flow to the roller bearings once the engine fires.
After cleaning off the grease, you then let them dry or blow dry them and THEN submerge them in oil; something like 30W. Turn the rollers repeatedly with the lifter(s) in the oil to make sure all the bearings receive a good oil coating.
As far as primeing them, there are differing views on that (what else is new?): Comp says NOT to prime them, that soaking is all they need. In fact, Comp says it's undesirable to prime them. Some guys insist on using an oil can or a pushrod to prime the lifters, but Comp has a different view. I never prime mine.
Trick, too, is not to let the engine sit for a prolonged period of time before it gets fired. I always use an oil priming tool to re-pressurize/re-fill the oil galleries before bolting down the intake.
Hope this helps.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
Last edited by JAKE; Dec 14, 2009 at 05:45 PM.
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
Thanks guys, I did swish them around in some mineral spirits before their bath. No sign of any grease just thought it might be a good idea. As far as the mess goes I'll pour off most of the oil then just hold the little pail I used over the lifter valley and drop them in after a little dip in assembly lube. Shouldn't be to messy. As far as priming goes I pull the coil wire and turn the engine over until it has good oil pressure before cranking it up.
Last edited by Weav's Vet; Dec 14, 2009 at 06:23 PM.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
When you are setting the lash, just spin the pushrod between your fingers while tightening the rocker arm nut. When you feel resistance...and it is very obvious..., tighten the nut another 1/4 turn and set the locking screw.
3/4 turn is too much, especially if you intend to rev the engine a bit. You are at risk of the lifter pumping up and you'll be tearing it apart again.
I've always run my engines between 0 and 1/4 turn depending on lifter and intended usage. My current engine is 500hp running stock LT1/4 lifters at 1/4 turn.
Race Director
Joined: Jan 2002
Posts: 12,261
Likes: 85
From: O'Fallon Missouri
Rotate the engine to TDC, determine if you're at the #6 or #1 firing position and set the lash on the appropriate valves. Once that is done, rotate the engine one time and set the rest.
When you are setting the lash, just spin the pushrod between your fingers while tightening the rocker arm nut. When you feel resistance...and it is very obvious..., tighten the nut another 1/4 turn and set the locking screw.
3/4 turn is too much, especially if you intend to rev the engine a bit. You are at risk of the lifter pumping up and you'll be tearing it apart again.
I've always run my engines between 0 and 1/4 turn depending on lifter and intended usage. My current engine is 500hp running stock LT1/4 lifters at 1/4 turn.
When you are setting the lash, just spin the pushrod between your fingers while tightening the rocker arm nut. When you feel resistance...and it is very obvious..., tighten the nut another 1/4 turn and set the locking screw.
3/4 turn is too much, especially if you intend to rev the engine a bit. You are at risk of the lifter pumping up and you'll be tearing it apart again.
I've always run my engines between 0 and 1/4 turn depending on lifter and intended usage. My current engine is 500hp running stock LT1/4 lifters at 1/4 turn.
You make it sound so easy!! Oh wait a minute it is!!
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
Rotate the engine to TDC, determine if you're at the #6 or #1 firing position and set the lash on the appropriate valves. Once that is done, rotate the engine one time and set the rest.
When you are setting the lash, just spin the pushrod between your fingers while tightening the rocker arm nut. When you feel resistance...and it is very obvious..., tighten the nut another 1/4 turn and set the locking screw.
3/4 turn is too much, especially if you intend to rev the engine a bit. You are at risk of the lifter pumping up and you'll be tearing it apart again.
I've always run my engines between 0 and 1/4 turn depending on lifter and intended usage. My current engine is 500hp running stock LT1/4 lifters at 1/4 turn.
When you are setting the lash, just spin the pushrod between your fingers while tightening the rocker arm nut. When you feel resistance...and it is very obvious..., tighten the nut another 1/4 turn and set the locking screw.
3/4 turn is too much, especially if you intend to rev the engine a bit. You are at risk of the lifter pumping up and you'll be tearing it apart again.
I've always run my engines between 0 and 1/4 turn depending on lifter and intended usage. My current engine is 500hp running stock LT1/4 lifters at 1/4 turn.
So many ways so many opinions..............
Last edited by Weav's Vet; Dec 15, 2009 at 06:12 AM.
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
Too many chiefs. If I were you, I would read it all, and make your own decisions.
10 ways to skin a cat, but reading through this thread lets me know some have no clue. One of the problems with the internet is the re-gurgitation of incorrect information. If it is repeated enough, it is believe. Then guys who really need help are screwed because it is posted yet again, or comes up in a search.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Too many chiefs. If I were you, I would read it all, and make your own decisions.
10 ways to skin a cat, but reading through this thread lets me know some have no clue. One of the problems with the internet is the re-gurgitation of incorrect information. If it is repeated enough, it is believe. Then guys who really need help are screwed because it is posted yet again, or comes up in a search.
10 ways to skin a cat, but reading through this thread lets me know some have no clue. One of the problems with the internet is the re-gurgitation of incorrect information. If it is repeated enough, it is believe. Then guys who really need help are screwed because it is posted yet again, or comes up in a search.
It's so critical to be able to distinguish correct information from the incorrect.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Mike, one way I can tell about the presence of grease is to take a lifter in one hand, then with my index finger I roll the roller wheel. If it feels really SMOOTH, I suspect grease.
I then submerge the lifter in solvent and while in the solvent I continue to roll the roller end. After several/many turns I begin to feel an increased roughness. The roughness results from the grease being dissolved.
I continue doing the rolling the roller while at the same time wipe away any grease from the body of the lifter; all this I do by hand. When all are done - greaseless - I dry them, then insert them into a bath of fresh engine oil. While holding the lifter submerged I start rolling the roller and the roughness dissappears and smoothness returns.
To avoid messes, I many times just cut the side out of two anti-freeze bottles, clean the interiors and fill them with either solvent or oil. I leave the lifters in the oil filled bottle (bottle laying on its side) and carry it over to the engine, sit the bottle in the lifter valley and drop in the lifters, one at a time.
Just how I do it, but I think you're past that point already.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
I then submerge the lifter in solvent and while in the solvent I continue to roll the roller end. After several/many turns I begin to feel an increased roughness. The roughness results from the grease being dissolved.
I continue doing the rolling the roller while at the same time wipe away any grease from the body of the lifter; all this I do by hand. When all are done - greaseless - I dry them, then insert them into a bath of fresh engine oil. While holding the lifter submerged I start rolling the roller and the roughness dissappears and smoothness returns.
To avoid messes, I many times just cut the side out of two anti-freeze bottles, clean the interiors and fill them with either solvent or oil. I leave the lifters in the oil filled bottle (bottle laying on its side) and carry it over to the engine, sit the bottle in the lifter valley and drop in the lifters, one at a time.
Just how I do it, but I think you're past that point already.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
Thread Starter
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
Okay, this is the way I'm adjusting the valves. I'm going to try the 1/4 turn preload and if it's noisy or just seems to loose it won't be hard to add more. This is from Shbox's site (which is quite informative). I like this because it's methodical and I can do it slow and do my best to get it right.
Another cylinder by cylinder method that does not require looking at the balancer position, follows:
(A remote starter switch is quite helpful)
Turn the engine in the normal direction of rotation until the exhaust lifter for the cylinder you are adjusting starts to move up (valve begins to open).
On the intake rocker arm, adjust for zero lash and add your desired preload.
Turn the engine over again until the intake lifter on the same cylinder comes all the way up (valve open) and then goes almost all the way back down (valve almost closed) .
Now, adjust the rocker arm for the exhaust valve on that cylinder to zero lash and add your desired preload. Continue the above procedure for each cylinder until all valves are adjusted to the same amount of preload. This procedure will work for any hydraulic lifter cam with adjustable rocker arms. Refer to this diagram posted above if you need visual reference. The reason I specify lifter movement in the above is because when you start off with completely loose rockers, there is no valve movement to watch.
Another cylinder by cylinder method that does not require looking at the balancer position, follows:
(A remote starter switch is quite helpful)
Turn the engine in the normal direction of rotation until the exhaust lifter for the cylinder you are adjusting starts to move up (valve begins to open).
On the intake rocker arm, adjust for zero lash and add your desired preload.
Turn the engine over again until the intake lifter on the same cylinder comes all the way up (valve open) and then goes almost all the way back down (valve almost closed) .
Now, adjust the rocker arm for the exhaust valve on that cylinder to zero lash and add your desired preload. Continue the above procedure for each cylinder until all valves are adjusted to the same amount of preload. This procedure will work for any hydraulic lifter cam with adjustable rocker arms. Refer to this diagram posted above if you need visual reference. The reason I specify lifter movement in the above is because when you start off with completely loose rockers, there is no valve movement to watch.