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[LS1] Decking the block

MiKExAUS

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Go to a glazier and get a piece of plate glass cut to suit the paper you're using. Wear gloves.
Good idea. What would be a good size for the LS block? Bigger than the bore (4 inch) or small and just go around the entire surface slowly and carefully? Also, wet (wd40) or dry? Thanks (really don't want to stuff this up)
 

shane_3800

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Good idea. What would be a good size for the LS block? Bigger than the bore (4 inch) or small and just go around the entire surface slowly and carefully? Also, wet (wd40) or dry? Thanks (really don't want to stuff this up)
Go bigger than the deck width. Ideally you would want a surface lager both ways but that is not practical.
 

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Also get thick glass at least 10mm thick and use spray on contact adhesive to glue the sand paper on. Yea wet and dry with WD-40 is fine.
 

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Good idea. What would be a good size for the LS block? Bigger than the bore (4 inch) or small and just go around the entire surface slowly and carefully? Also, wet (wd40) or dry? Thanks (really don't want to stuff this up)
Bigger than the deck, use a full sheet, or half sheet of wet and dry, probably 400 grit.
 

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The Tech Service Bulletin 00-06-01-012J is worth a read ;)

GM does not recommend abrasive methods to clean gasket surfaes, especially since the abrasive grit makes its way between the piston and cylinger walls and then into the engine. According to GM, abrasive materials left behind (from scotchbrite pads or surface conditioning disks) can cause premature bearing failure in as little as 2,200kms :oops: GM recommends using a razor blades or plastic gasket scrapers, or GM low VOC gasket cleaner p/n: 88900163 (brake part cleaner). Obviously they expect you don't gouge the deck :p

Having said that, I've got an OCD method I use. I turn the engine so pistons are not at the top of the block. Then use a lint free cloths to wipe the cylinder bore to piston junction before appling a wedge of grease around tha perifery of that area to stop/minimise crud getting between these components. When I've done it, I then very carefully clean the block deck using blade followed by an abrasive scotchbrite pad (yes not ideal). Obviously one tries to avoid gouging the deck with the blade or focus on one spot too long with a pad, but generally such isn't a problem on the few iron blocks I've done.. Sadly with alloy blocks, stuff happens... After the scrap and rub, I then carefully wipe the deck and bores using cloth. I spray the cloth with cleaner and when wiping i stay away from the grease wedge. I finally take away the grease wedge using a right angle plastic scraper and a cutting action before wiping reminants way using another clean cloth while trying not to push grease & crud down between piston and cylinder wall while wiping. It's served me ok but doing such on an old school unstressed iron block 4 cylinder is different to more modern alloy block V8.

I've always thought i'd make a bore plug (similar to this) that i could use above the piston to supplament the grease wedge (to be sure to be sure). But just didn't do so much engine work and never got around to it.

So it you start sanding the deck, just be carefull where the grit ends up cause grit, oil and bearings don't make great bedfellows.

PS: here's another persons method which aint hugely different to what i've done in the past (and again it looks like iron block) ... And another thread that contains comments about abrasive getting to where is shouldn't...
 
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MiKExAUS

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The Tech Service Bulletin 00-06-01-012J is worth a read ;)

GM does not recommend abrasive methods to clean gasket surfaes, especially since the abrasive grit makes its way between the piston and cylinger walls and then into the engine. According to GM, abrasive materials left behind (from scotchbrite pads or surface conditioning disks) can cause premature bearing failure in as little as 2,200kms :oops: GM recommends using a razor blades or plastic gasket scrapers, or GM low VOC gasket cleaner p/n: 88900163 (brake part cleaner). Obviously they expect you don't gouge the deck :p

Having said that, I've got an OCD method I use. I turn the engine so pistons are not at the top of the block. Then use a lint free cloths to wipe the cylinder bore to piston junction before appling a wedge of grease around tha perifery of that area to stop/minimise crud getting between these components. When I've done it, I then very carefully clean the block deck using blade followed by an abrasive scotchbrite pad (yes not ideal). Obviously one tries to avoid gouging the deck with the blade or focus on one spot too long with a pad, but generally such isn't a problem on the few iron blocks I've done.. Sadly with alloy blocks, stuff happens... After the scrap and rub, I then carefully wipe the deck and bores using cloth. I spray the cloth with cleaner and when wiping i stay away from the grease wedge. I finally take away the grease wedge using a right angle plastic scraper and a cutting action before wiping reminants way using another clean cloth while trying not to push grease & crud down between piston and cylinder wall while wiping. It's served me ok but doing such on an old school unstressed iron block 4 cylinder is different to more modern alloy block V8.

I've always thought i'd make a bore plug (similar to this) that i could use above the piston to supplament the grease wedge (to be sure to be sure). But just didn't do so much engine work and never got around to it.

So it you start sanding the deck, just be carefull where the grit ends up cause grit, oil and bearings don't make great bedfellows.

PS: here's another persons method which aint hugely different to what i've done in the past (and again it looks like iron block) ... And another thread that contains comments about abrasive getting to where is shouldn't...
Thanks mate, appreciate the effort you put in your post. And the grease trick is brilliant. I'll def do that. I have seen this bulletin which is why I went down the razor blade route. Can anyone comment on deck flatness specs? My service manual says 0.22mm but I've seen .004in max on most American forums (along length of block). Also, how accurate are stainless metal rules for measuring flatness?
 
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Skylarking

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Thanks mate, appreciate the effort you put in your post. And the grease trick is brilliant. I'll def do that. I have seen this bulletin which is why I went down the razor blade route. Can anyone comment on deck flatness specs? My service manual says 0.22mm but I've seen .004in max on most American forums (along length of block). Also, how accurate are stainless metal rules for measuring flatness?
As is, a ruler is not a straight edge. They are different tools used to measure different things. One companies ruler may indeed be rather straigh along the edge but if it flexes along the thin side, it will impact any flatness measurements you try and make. Guess that's why straight edges are thick and have a beveled and hardened edge...

I also had a quick look at the VF workshop manual but there are no specs on deck flatness (that i saw cause navigating the PDF is a pain without working hyperlinks). I'm sure everyone has their view but I'd say the flatter would be the better... Anyway, from this article, which you may or may not have seen, it states:

The maximum acceptable limit for out-of-flat on the deck surface of a cylinder head or engine block will vary with the application and type of gasket.
For a pushrod engine with cast iron heads, out-of-flat should generally be .003 in. (0.076 mm) or less for a V6 head, .004 in. (0.102 mm) or less for a V8 or four cylinder head, and no more than .006 in. (0.152 mm) in a straight six cylinder head. Aluminum heads and performance applications should be even flatter – no more than .002 in. (.05 mm) out-of-flat in any direction and less than .001 inches out-of-flat across a three-inch span in any direction. If you want it to seal, it has to be as flat as you can get it.

The real question is, how deep is the gouge and how much metal will you have to remove to get it to play nice with your gasket. It may be worth a trip to an engine builder to have a chat how to best approach it (but for the lockdown). With the correct sanding technique, hopefully you can avoid creating high and low spots but it's a pain working on a block within the cars engine bay (if indeed its still in there)...
 
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EYY

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Just take a small flat piece of steel, say 20x10x50 and wrap a piece of 800 grit around it. Spray some WD40 and place flat on the sealing surface. Sand in a crosshatch pattern with light pressure keeping your 'sanding block' flat. You shouldn't need more than a few light strokes to remove any raised edges.

You only want to remove the high spots around your gouges. You won't get a satisfactory result through sanding if you wanted to totally remove those gouges, even with glass on such a long sealing surface. You'll do more harm than good because while it'll be smooth, it won't be flat along the length of the surface.

The glass technique will work fine on smaller motorcycle heads/cylinders and the like. If you want to rid the surface of those gouges, you'll need to remove the engine and disassemble to have the block decked professionally.

Just tidy it up and run it. Nothing to worry about imo. Look at the surface finish on the block, they're pretty rough from factory anyway.
 

MiKExAUS

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Hey gang, good news. I got the engine back together finally with some serviced heads. I left the gouges in the block and just cleaned up the surface the best I can with razor blades. I think I used a 50 pack in total just using new ones as soon as I nicked them in any way. Carefully using the blade as parallel as possible to the block to get the residue off. It cleaned up pretty well. There was slight discolouration in the block but I wasn't worried. I checked the flatness with a straight edge and feeler gauge. All checked out. New genuine gaskets and ZERO leaks! Didn't use any sandpaper or Scotch Brite. I didn't even sand down the small gouges I made as the feeler gauge didn't indicate it made a considerable raise in the surface. Thanks again for your help.
 
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