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Engine Specific Info and Questions => IDI Engine => Topic started by: ilikevwdiesel on January 31, 2009, 08:16:36 am
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anybody ever had one milled? I just had one cut about .006" to flatten it out. not sure if it's going to work, the Bentley says it's a no no. This is one of the 1.6 engines with 11mm head bolts. Should I have just left it and tried ARP studs? Junked it? Opinions please.
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mine was resurfaced....you just have to make sure you do a piston protrusion check...if they had to take to much then they will need to shave your pistons too.....
I'm glad I did mine...
but I would rather not have pistons shaved so if I had a 3 notch gasket I would probably NOT shave it since you are almost out of spec when at 3 notch anyway...
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any idea how much was taken off the head? how many thousands?
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any idea how much was taken off the head? how many thousands?
I dont remember if they even told me??? my machine shop builds lots of race engines and they wanted to straighten it out so I said go ahead...I did not even consult Bentley..
BTW i'm no engine builder expert...I leave all that jazz to the machine shop... :oops:
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I just had mine done at Rimco after having it f'd up somewhere else. Rimco took .009" after the first guy shaved some off too for an estimated .015 - .020 total material removed.
Shaving the head does nothing for piston protrusion or gasket thickness. If anything you might want to check that there's enough valve recess after skimming the head but Bentley only gives a maximum dimension and not a minimum.
Chris
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ok guys thanks...did the machine shops say anything about line boring the cam journals? and are you guys up and running these heads now?
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I just had mine done at Rimco after having it f'd up somewhere else. Rimco took .009" after the first guy shaved some off too for an estimated .015 - .020 total material removed.
Shaving the head does nothing for piston protrusion or gasket thickness. If anything you might want to check that there's enough valve recess after skimming the head but Bentley only gives a maximum dimension and not a minimum.
Chris
oops I nee more coffee...:oops: ...I was getting my block resurface and my head resurface mixed up...you are right the head resurface will have nothing to do with piston protrusion...
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Definitely have the cam journals checked.
You might need to shorten your valves... if that is even possible on these engines?
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Definitely have the cam journals checked.
You might need to shorten your valves... if that is even possible on these engines?[/quote
the machinist did grind the valve stems a bit but I think it was just to remove any burr that might be there. I have the cam in the head and the valves adjusted, it seems to turn ok. since the gasket face is flat now it shouldn't ? change when it's torqued onto the head deck JA?
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Why shorten the valves? The hydraulic lifters will take up the difference.
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yeah it won't do anything to shorten the valves the seats are recessed into the head.
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The machinist should tell you if it needs a line bore. I had mine resurfaced and it didn't need a line bore. If the cam turns ok on the assembled head it should be ok.
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Why shorten the valves? The hydraulic lifters will take up the difference.
If you grind the valve seats and/or recut the valves, you are SUPPOSED to check the valve stem projection into the lifter bores, ESPECIALLY on hydraulic lifter heads. Otherwise, the lifter might not take up the difference. This is especially true when you're reusing old lifters that might not drain down before you start your engine.
Why do this? So the valves do no open too much and get clobbered by the pistons.
Smart machinists figured this out years ago, and now Bentley makes note of it in the new books for the TDI engines. I just had a TDI head reworked, and the machinist requested the cam and the lifters after he did the valve work so that he could determine how much to grind off the valve tips.
This makes sense for the mechanical lifter heads too, so that you don't have to go out an buy a ton of thin shims (assuming the labor on the valve work is cheaper).
If your head is going in for first time valve work, you should be able to get away with leaving the valve tips alone. But if you're not sure, is a very good idea to have you machinist check the projection.
Also, line bore is a very good idea. If your head was severely warped, you can be sure there is wear in the cam journals from the warpage. Have them check that too.
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thanks quantum. The head was .006 warped on the gasket face, I would call that moderate? I have it all back together now with the valves adjusted, the cam spins like it should and it's flat so it should be ok. I am still a little concerned about piston to valve clearance. I am pretty sure this block needs a 3 notch gasket as the piston protrusion is pretty high. I will know for sure sometime tomorrow when that gets measured. Hopefully it will call for a 2 notch and I'll just use a 3 unless someone knows how to check that before installing the head?
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Good to know about the valve tips. So would the machinist need to cut new grooves for the keepers? I would think that you'd have to remove a lot of material from the bottom of the head to have the lifters completely compressed when the valves are closed. How much travel does a lifter need to be able to expand?
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grinding the valve stem has nothing to do with refacing the gasket surface on the cylinder head. If you look at a 1.6 head, you'll see the valve face is recessed into the head about .050 or so. The main reason a machinist would grind the tip of the valve stem is to remove a burr that may have worn onto the tip from the lifter bucket rubbing against it. Valve seats tend to sink after many miles of use, there is a limit to it before they must be replaced and that would be another reason to grind the valve stem tip. If the seat is sunk and the valve is refaced, the stem may stick up too high in the lifter bore meaning you would have to install a very thin shim (in mech. lifter engines) or in a bad case not be able to set the proper clearance at all and end up with a valve that stays open all the time. As with the valve face, you can only grind so much off the tip of the stem before you interfere with the keepers, at which point the valve is junk and needs to be replaced.
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grinding the valve stem has nothing to do with refacing the gasket surface on the cylinder head. If you look at a 1.6 head, you'll see the valve face is recessed into the head about .050 or so. The main reason a machinist would grind the tip of the valve stem is to remove a burr that may have worn onto the tip from the lifter bucket rubbing against it. Valve seats tend to sink after many miles of use, there is a limit to it before they must be replaced and that would be another reason to grind the valve stem tip. If the seat is sunk and the valve is refaced, the stem may stick up too high in the lifter bore meaning you would have to install a very thin shim (in mech. lifter engines) or in a bad case not be able to set the proper clearance at all and end up with a valve that stays open all the time. As with the valve face, you can only grind so much off the tip of the stem before you interfere with the keepers, at which point the valve is junk and needs to be replaced.
I think you will be fine with a 2 notch if that is what was on it to begin with, if the cam spins freely it's fine. I've had a couple heads milled and like was said earlier it has nothing to do wih piston protrusion as the head is flat anyway and as long as you can rotate the engine with no valve contact there will be no problem. I think I would put the 11m/m studs in it though as those 11m/m headbolts don't go in the block very far at all compared to the 12m/m ones. I'll never use headbolts again and those ARP studs screw in farther and torque so nice with none of that creaking and jerking that makes you feel uneasy wondering if something wrong just happened. Also don't forget to retorque the head after it reaches normal temp and then cools down, especially with the fiber gasket if that is what you are using. :D