Why I say to have your block decked

[BogusSVO]

I commonly get asked why I want to deck a block.

Some look at me and think it is just to run up the machine bill. That is not it, it is because it is needed 99.999% of the time.

I had to deck 4 blocks the other day, 4g63 6 bolt, 4G63 7 bolt, 4G63 and a 4GJS

The 4GJS had the lowest miles on it with about 79k, and been NA everyday from the factory.

Now for the pics....

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

Most of the distortion shown in the above pics will not show up with a straight edge and feeler gauge.

The feeler gauge will "bridge" the fire ring grooves and other small distorted areas.

So if you are doing a rebuild, have the deck the block.

Want to run a MLS HG, Deck the block.

In short, if the block is out, have the block decked.

 

[Sebba]

Yowza, that's terrible. How much had you taken off on that pass?

 

[BogusSVO]

Seeba, those are just random pics from all 4 blocks, I do a getting to know you pass of .001 to check my set up.

Most blocks clear up between .003-.005 total cut.

 

[kamikazeredneck]

This is why we need more engine builders like you doing builds for the DSM community. The attention to small details makes everything work just that much better and longer!

 

[fallenauthority]

Very good info you provide. Glad we have you here on tuners. I actually plan to build a 6 bolt here some day soon and want to delve into the assembly portion myself. Just something I have always wanted to do. I find your info you provide on multiple threads here very helpful.

 

[JacksonAuto]

In addition, if you don't deck the block then the surface is not paralell with the mains. Then when the block is bored the cylinders aren't square to the deck or the crank.

 

[95talongirl]

Great info and photos! I truly beeline one of the reasons my car seems to run well with no issues is because I had the machine shop deck the block as well as balance the entire rotating assembly. Heck you'd never know the car is running without balance shafts. So yes the little bit extra it costs it worth it if you are looking for longevity. Mine ended up with .004 taken off

 

[BogusSVO]

In addition, if you don't deck the block then the surface is not paralell with the mains. Then when the block is bored the cylinders aren't square to the deck or the crank.

JAM, I will have to half agree with you on this.

Some boring equipment stands to set up off the deck surface, so if there is a tilt or twist to the block surface it will bore an odd hole.

Now other Boring stand equipment still sets up off the mains, and the deck surface is just used for the hold downs.

Now the Kwik-way air lift sets up off the deck surface.

The kwik-Way EBF uses main adapters and locks down on the mains.

But The Air lift stand is much more commonly in use in machine shops than the EBF.

 

[JacksonAuto]

It also creates a similar situation but instead of relying on an accurate deck you're relying on the housing bores. So if the align bore is off then you're still going to end up with crooked cylinders. There's no way around it- everything has to be perfect.

 

[Bo0sTdTsI]

That is good to know, thanks for the info.

 

[madscientist91]

79K N/A? Did he drive around without coolant? I wish i had the time and the resources to pull my block and take it to a shop to have it decked during my current build. I did a feeler gauge check but its always more comforting to know its done 100% right.

 

[BogusSVO]

No the engine was pulled for a spun rod bearing.

The factory blocks are machined "green" so it shifts and moves as it is heat cycled. After a bit they will take a set and run that way.

The point of this thread is to show that about every block deck is out, yes a composite gasket will absorb most of the distortion.

Now madscientist, I could take your block that you checked for flat, and mill it, and odds are, it would cut like the above pics.

 

[crimsondragon]

So does that distortion happen because of heat cycles and/or from torquing the headstuds down? Is there ever a case where a block doesn't need to be decked? If a block was decked previously last rebuild, will it need to be decked again?

 

[Twinturbo120]

I wonder if one of those blocks is mine >_>

 

[BogusSVO]

I wonder if one of those blocks is mine >_>

IIRC the last 3 pics are <_<