0.004" Block Flatness Warrants Decking?? - Blown HG aftermath

V8 GTFO Lesbic WGN · 11-13-2013, 10:44 AM

Factory Service Manual calls warping limit of 0.00098" (0.025 mm), using high precision Starrett straight edge I am at 0.004" (0.1016 mm), a difference of only 0.003" (0.0767 mm)

Does 0.003" warrant for a block deck machining? The heads have being decked and are within spec. I will be using Subaru OEM MLS replacement gaskets.

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bjohnson_55 · 11-13-2013, 11:29 AM

If you want to do it right, yes. If not, no.

Rally2 · 11-13-2013, 12:19 PM

One way to look at this is yeah it's only 0.003" out. Another perspective is it's 4x the allowable limit.

V8 GTFO Lesbic WGN · 11-13-2013, 12:27 PM

Well I want to do it right, problem is I do not trust local machinist, I am afraid the 0.003" may turn into 0.03" or worst so just trying to ascertain if I wing it or take the chance with the local red neck "V8 iron block" familiar machine shop.

cowboy_Rob · 11-13-2013, 12:58 PM

4x the spec I would definitely want it fixed. If you have to just ship ship the block to a machine shop that knows subarus. Bare block halves really aren't very heavy I can't see shipping costing very much

fastblueufo · 11-13-2013, 01:42 PM

Maximum out is .002 allowable by most standards with deck flatness.

V8 GTFO Lesbic WGN · 11-13-2013, 02:29 PM

^I don't follow you, I know what the spec is: Factory Service Manual calls warping limit of 0.00098"

Are you saying that a machine shop would only guarantee 0.002"?

300zxturboftw · 11-14-2013, 01:16 AM

Quote:

Originally Posted by V8 GTFO Lesbic WGN

^I don't follow you, I know what the spec is: Factory Service Manual calls warping limit of 0.00098"

Are you saying that a machine shop would only guarantee 0.002"?

Take it to a machine shop with a cnc machine that can laser it out perfectly. Will cost the same as another machine shop who cuts it a different/less technological way and your deck will be almost perfectly flat/square.

11-13-2013, 10:44 AM	#1
V8 GTFO Lesbic WGN Scooby Specialist Member#: 191212 Join Date: Oct 2008 Chapter/Region: MWSOC Location: Imported to Detroit :-( Vehicle: 2007 FXT-5MT E85 20G TD06SL2 Kinugawa	0.004" Block Flatness Warrants Decking?? - Blown HG aftermath Factory Service Manual calls warping limit of 0.00098" (0.025 mm), using high precision Starrett straight edge I am at 0.004" (0.1016 mm), a difference of only 0.003" (0.0767 mm) Does 0.003" warrant for a block deck machining? The heads have being decked and are within spec. I will be using Subaru OEM MLS replacement gaskets. * Registered users of the site do not see these ads. Last edited by V8 GTFO Lesbic WGN; 11-13-2013 at 11:07 AM.

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11-13-2013, 11:29 AM	#2
bjohnson_55 Scooby Specialist Member#: 216580 Join Date: Jul 2009 Chapter/Region: MWSOC Location: INDY	If you want to do it right, yes. If not, no.

11-13-2013, 12:19 PM	#3
Rally2 Scooby Newbie Member#: 132023 Join Date: Nov 2006 Chapter/Region: W. Canada Location: Alberta Canada Vehicle: 2005 STI blue	One way to look at this is yeah it's only 0.003" out. Another perspective is it's 4x the allowable limit.

11-13-2013, 12:27 PM	#4
V8 GTFO Lesbic WGN Scooby Specialist Member#: 191212 Join Date: Oct 2008 Chapter/Region: MWSOC Location: Imported to Detroit :-( Vehicle: 2007 FXT-5MT E85 20G TD06SL2 Kinugawa	Well I want to do it right, problem is I do not trust local machinist, I am afraid the 0.003" may turn into 0.03" or worst so just trying to ascertain if I wing it or take the chance with the local red neck "V8 iron block" familiar machine shop.

11-13-2013, 12:58 PM	#5
cowboy_Rob Scooby Specialist Member#: 194062 Join Date: Nov 2008 Chapter/Region: MAIC Location: Camp Hill PA Vehicle: 2003 Impreza WRX PSM	4x the spec I would definitely want it fixed. If you have to just ship ship the block to a machine shop that knows subarus. Bare block halves really aren't very heavy I can't see shipping costing very much

11-13-2013, 01:42 PM	#6
fastblueufo Scooby Specialist Member#: 212154 Join Date: May 2009 Chapter/Region: South East Location: fast performance tuning Vehicle: 02 billet crank pauter rods, pt5857, E85	Maximum out is .002 allowable by most standards with deck flatness.

11-13-2013, 02:29 PM	#7
V8 GTFO Lesbic WGN Scooby Specialist Member#: 191212 Join Date: Oct 2008 Chapter/Region: MWSOC Location: Imported to Detroit :-( Vehicle: 2007 FXT-5MT E85 20G TD06SL2 Kinugawa	^I don't follow you, I know what the spec is: Factory Service Manual calls warping limit of 0.00098" Are you saying that a machine shop would only guarantee 0.002"?