how many times can you machine heads?
Thread Starter
|
Drifting
Joined: Dec 2017
Posts: 41
Likes: 0
how many times can you machine heads?
2004 Disco 2 4.6 124k
Doing a head gasket set on my 2004 d2. As I am taking the bolts out of the lower intake manifold the entire manifold sprung up as if it were under a ton of torsion.When the bolts all came out the manifold was free floating but I cannot get it out without removing the valve covers. The valve covers are overlapping the lower intake manifold. If the heads had not ever been machined I imagine they would be taller and this interference would not take place. This makes me think my heads have been machined and are now not lining up well with the intake manifold. Can anyone speak on this.
Doing a head gasket set on my 2004 d2. As I am taking the bolts out of the lower intake manifold the entire manifold sprung up as if it were under a ton of torsion.When the bolts all came out the manifold was free floating but I cannot get it out without removing the valve covers. The valve covers are overlapping the lower intake manifold. If the heads had not ever been machined I imagine they would be taller and this interference would not take place. This makes me think my heads have been machined and are now not lining up well with the intake manifold. Can anyone speak on this.
There is only a .01 - .02 tolerance for machining these heads. Just depends on how warped the heads are before having them machined.. Mine were fairly warped, machine shop did .014 decking -- even though they had never been machined before they can never be machined again.
If the heads were previously machined, any reputable shop should have stamped how much was removed in the corner of the head to save time the second go around etc.
To measure warpage, find a known flat / straight bar and place it diagonally across the head. With a feeler gauge, measure how thick / thin gaps are. Then do the other diagonal and measure again.
its easy to do and gives you a rough idea on how warped or not warped your heads are. Obviously machine shops have much better equipment to measure so this is mearly an estimation of what you can expect.
Given the milage of your disco, is just take them to a machine shop and have them work their magic and be done with it.
To measure warpage, find a known flat / straight bar and place it diagonally across the head. With a feeler gauge, measure how thick / thin gaps are. Then do the other diagonal and measure again.
its easy to do and gives you a rough idea on how warped or not warped your heads are. Obviously machine shops have much better equipment to measure so this is mearly an estimation of what you can expect.
Given the milage of your disco, is just take them to a machine shop and have them work their magic and be done with it.
Thread Starter
|
Drifting
Joined: Dec 2017
Posts: 41
Likes: 0
If the heads were previously machined, any reputable shop should have stamped how much was removed in the corner of the head to save time the second go around etc.
To measure warpage, find a known flat / straight bar and place it diagonally across the head. With a feeler gauge, measure how thick / thin gaps are. Then do the other diagonal and measure again.
its easy to do and gives you a rough idea on how warped or not warped your heads are. Obviously machine shops have much better equipment to measure so this is mearly an estimation of what you can expect.
Given the milage of your disco, is just take them to a machine shop and have them work their magic and be done with it.
To measure warpage, find a known flat / straight bar and place it diagonally across the head. With a feeler gauge, measure how thick / thin gaps are. Then do the other diagonal and measure again.
its easy to do and gives you a rough idea on how warped or not warped your heads are. Obviously machine shops have much better equipment to measure so this is mearly an estimation of what you can expect.
Given the milage of your disco, is just take them to a machine shop and have them work their magic and be done with it.
Camel Trophy
Joined: Aug 2014
Posts: 4,743
Likes: 985
From: Southwestern Virginia
You can mill the heads as far as .015" can't you? Maybe .020"; I can't recall. It's in the overhaul manual. Easy to find. There's just a .002" tolerance, meaning no point on the head can be more than .002" lower than the highest point.
There's no set number of times you can mill or deck a head. It all depends on how much material needs taken off each time.
There's no set number of times you can mill or deck a head. It all depends on how much material needs taken off each time.
Recovery Vehicle
Joined: Jun 2017
Posts: 1,238
Likes: 240
From: Alabama + Vegas + Texas
My local machine shop let me watch them mill my heads. It was neat! One head took 4 passes before the low points started getting cut. Each pass was milling .001" of metal off.
if you are using a thicker gasket such as the all metal Cometic instead of black silicon+metal skinny gaskets then you *want* more metal shaved off of your heads, too!
*thicker gasket gaps between block and factory head height reduce your compression ratio a little from factory
if you are using a thicker gasket such as the all metal Cometic instead of black silicon+metal skinny gaskets then you *want* more metal shaved off of your heads, too!
*thicker gasket gaps between block and factory head height reduce your compression ratio a little from factory
Pro Wrench
Joined: Oct 2011
Posts: 1,709
Likes: 137
From: NE PA
My local machine shop let me watch them mill my heads. It was neat! One head took 4 passes before the low points started getting cut. Each pass was milling .001" of metal off.
if you are using a thicker gasket such as the all metal Cometic instead of black silicon+metal skinny gaskets then you *want* more metal shaved off of your heads, too!
*thicker gasket gaps between block and factory head height reduce your compression ratio a little from factory
if you are using a thicker gasket such as the all metal Cometic instead of black silicon+metal skinny gaskets then you *want* more metal shaved off of your heads, too!
*thicker gasket gaps between block and factory head height reduce your compression ratio a little from factory