I have yet to see a LS block, whether it's from GM or one of the aftermarket manufacturers, that will finish-machine to the blueprint spec of 9.240" Brand new blocks are often less than that, and still require decking to correct both side to the same height, measured from the crankshaft centerline. Also important is to assure the decks are a perfect 90 degrees from each other.
This is why we had to make my brand new block from GM a 9.229 deck height. For those who do not know they start off as 9.240. Also it should be noted that in NA form you would never have a problem with the variance in the block. Probably not even a mildly boosted one… but we all like perfection.
Yep, the gm stuff is suspect too. and it isn't always about fixing it to not have a failure, but to make sure you can have the most efficient and powerful motor possible!
@@paragonengines1924 I have an uncle who spent his whole working life in the GM engine plant in Lansing, MI. And the stories he could tell. Add that to a friend who worked in the "lemon room" at the GM factory in Arlington, TX...
and this is also why most machine shops want MINIMUM $650 just to "true" a block... Line hone, deck the block, bore and hone... my machine shop is taking on average 6 months to do this type of work.. I have 2 6.0 blocks with them at this time waiting for the process to be completed.
Do you accept work if i shipped a block to you? And I had an LS7 decked by local machine shop (traditional wheel milled), texas speed cnc heads, put together and coolant is leaking between block and heads. I see the cut grooves and can even feel irregularities in some spots. I was told by one place they should have never touched it being aluminum. Is there any truth to that?
Yes, we take in engines from all over. Decking an aluminum block is a common practice, but you have to know what you are doing when you have two dissimilar materials being machined.
Some blocks are pretty close, maybe .003-.004". The worst LS I've seen took about .012". The tilt won't cause a gasket failure, but any warpage of more than .005" over a 4" area can cause some problems.
Sorry for the stupid question but when i see a block getting decked AND the cut looks to be deeper on the front cylinders (both sides) wouldn't this indicate a problem with the setup ?
You are correct, but it wasn't my set up that was wrong. The bar the block sits on is within .0005" along the Z axis. However GM machined the block is where the errors occurred.
The aluminum block benefits are weight and cooling. The iron blocks are stronger but have a 100 LBS weight penalty. We usually don't recommend going over 1000 HP on stock aluminum blocks because of the distortion that happens in the sleeves.
@@paragonengines1924 Thanks, I appreciate the reply. Goals are well south of a 1000, so I'll go with alloy for the weight savings. Do you find the alloy blocks always need deck surfacing, like the steel ones??
Unless it is the LS7 or LS9 blocks, they are going to be out one way or another. They might be flat, but they are going to be warped or tilted in reference to the centerline of the crank.
@@paragonengines1924 Thank you for replying. Utube was a little slow on the notification, of your reply. My little LS3 rebuild, just went up in price...again. It's a pay to play game. Thanks again.
It will affect compression, but it is adjusted with gaskets and other machining to get the desired ratio. Same thing with the clearances. We check every build to make sure everything clears and is the right compression for the application.
The title of the video… Why u need to deck an LS Block Q1. Are LS blocks more likely than other blocks to require decking, or always need decked ? Q2. Are other blocks less likely to require decking ?
The main reason is that most people say you don't have to do any machining to an LS to make power. Other blocks can be better or worse than LS tolerances, so they should all be checked for the best performance.
9000’ths off what would you new pushrod ball park be? 8.300? I suck at math ….i apologize in advance, all i know how to do is count money and read a tape measure
Great video highlighting not only correction of the sealing surface but also squaring up the block end-to-end as well as side-to-side👍👍
I have yet to see a LS block, whether it's from GM or one of the aftermarket manufacturers, that will finish-machine to the blueprint spec of 9.240" Brand new blocks are often less than that, and still require decking to correct both side to the same height, measured from the crankshaft centerline. Also important is to assure the decks are a perfect 90 degrees from each other.
Trying our best!
This is why we had to make my brand new block from GM a 9.229 deck height. For those who do not know they start off as 9.240. Also it should be noted that in NA form you would never have a problem with the variance in the block. Probably not even a mildly boosted one… but we all like perfection.
Yep, the gm stuff is suspect too. and it isn't always about fixing it to not have a failure, but to make sure you can have the most efficient and powerful motor possible!
@@paragonengines1924 yes sir! I really enjoy these videos, thank you
@@paragonengines1924 I have an uncle who spent his whole working life in the GM engine plant in Lansing, MI. And the stories he could tell. Add that to a friend who worked in the "lemon room" at the GM factory in Arlington, TX...
Those would be some good stories to hear around the campfire!
With the dramatic videos you post its amazing that an LS even starts and runs lol.
You would think nothing would run! Shows what you can get away with but doesn't mean it will last!
Well I'm having my deck. That said, it lasted 356,000 miles, it didn't leak, And it was abused like a red headed step child.
Love the videos 💪🏽
I appreciate it!!
and this is also why most machine shops want MINIMUM $650 just to "true" a block... Line hone, deck the block, bore and hone... my machine shop is taking on average 6 months to do this type of work.. I have 2 6.0 blocks with them at this time waiting for the process to be completed.
Yep! It does take time and money to do the work right. Most shops around are pretty far behind if they are doing it right.
Glad I'm not where you are The best performance shop in the county here charges $175 no problem
Do you accept work if i shipped a block to you? And I had an LS7 decked by local machine shop (traditional wheel milled), texas speed cnc heads, put together and coolant is leaking between block and heads. I see the cut grooves and can even feel irregularities in some spots. I was told by one place they should have never touched it being aluminum. Is there any truth to that?
Yes, we take in engines from all over. Decking an aluminum block is a common practice, but you have to know what you are doing when you have two dissimilar materials being machined.
Great video, would machining 10 thou off change the compression ratio ?
Yes, LS engines usually see 1 CC per .005" machined.
Was this an Aluminum or Iron block? Is it normal to do this "dry". The red nozzles are blow off guns essentially.?
This was an Iron block. The type of insert we use works best dry. The red nozzles are where the coolant would come out if the program called for it.
At what point after this much decking would you need to mill the intake manifold so it will fit between the heads properly?
Usually, a combination of milling on the heads and block over .035" will cause fitment issues with the intake.
How much do ls blacks usually take and how.much before it starts to be a problem
Some blocks are pretty close, maybe .003-.004". The worst LS I've seen took about .012". The tilt won't cause a gasket failure, but any warpage of more than .005" over a 4" area can cause some problems.
Awesome video! What is the worst one you have ever seen?
SBC that was .028" higher from one side to the other!
@@paragonengines1924 that’s a lot!
Sorry for the stupid question but when i see a block getting decked AND the cut looks to be deeper on the front cylinders (both sides) wouldn't this indicate a problem with the setup ?
You are correct, but it wasn't my set up that was wrong. The bar the block sits on is within .0005" along the Z axis. However GM machined the block is where the errors occurred.
@@paragonengines1924 where did GM square off of when they machine?
In your experience, are the alloy blocks, any better or worse than the steel blocks??
The aluminum block benefits are weight and cooling. The iron blocks are stronger but have a 100 LBS weight penalty. We usually don't recommend going over 1000 HP on stock aluminum blocks because of the distortion that happens in the sleeves.
@@paragonengines1924 Thanks, I appreciate the reply. Goals are well south of a 1000, so I'll go with alloy for the weight savings.
Do you find the alloy blocks always need deck surfacing, like the steel ones??
Unless it is the LS7 or LS9 blocks, they are going to be out one way or another. They might be flat, but they are going to be warped or tilted in reference to the centerline of the crank.
@@paragonengines1924 Thank you for replying. Utube was a little slow on the notification, of your reply.
My little LS3 rebuild, just went up in price...again.
It's a pay to play game.
Thanks again.
Yeah, everything is going up. Hopefully you can get it done soon!
Forgive me if this is a stupid question but I'm a novice at best mechanically, how does all this affect compression and clearances?
It will affect compression, but it is adjusted with gaskets and other machining to get the desired ratio. Same thing with the clearances. We check every build to make sure everything clears and is the right compression for the application.
The title of the video…
Why u need to deck an LS Block
Q1. Are LS blocks more likely than other blocks to require decking, or always need decked ?
Q2. Are other blocks less likely to require decking ?
The main reason is that most people say you don't have to do any machining to an LS to make power. Other blocks can be better or worse than LS tolerances, so they should all be checked for the best performance.
@@paragonengines1924
Thx
I have yet to see the last craze....other than abundant... Ain't it just ain't it 😎 lols
Gotcha!
9000’ths off what would you new pushrod ball park be? 8.300? I suck at math ….i apologize in advance, all i know how to do is count money and read a tape measure
You have about .100" of stock lifter plunge to play with, so 7.400" would be fine.
@@paragonengines1924 nice……now i can sleep at night