Shaving/Milling head, how much is safe or been don
10-04-2010, 11:56 AM
#1
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Shaving/Milling head, how much is safe or been don
so after overheating my 03 s2000 now my head is warped and has to be milled .030 to be level again.
is that going to be ok?
someone said a new tensioner with more load would be needed?
I searched and found mixed responces
thank you
is that going to be ok?
someone said a new tensioner with more load would be needed?
I searched and found mixed responces
thank you
10-05-2010, 03:50 AM
#3
I've milled up to a combined 0.5mm off a block and head. This was on a F24C stroker where the rod/piston combination put the pistons lower in the deck than I wanted.
I ordered a new tensioner/chain for the motor but it didnt turn up in time so I ran it with a used chain and tensioner. It had some slight rattle at idle which went away after I put the new chain/tension in. Changing the tensioner only didnt help, I had to also fit the new chain.
So from a chain slap perspective you should really fit a new chain and tensioner.
Your other consideration is head to piston clearance. You really need around 0.032 to 0.040" for the revs our engines do. The standard head gasket depending on supplier are around 0.032" thick so the easiest way to check clearance is to lay the head on the motor without any gasket and check you can turn it over without the pistons hitting the head. Ideally you want to make lots of measurements in different places but the basic check described will ensure you have at least the head gasket thickness worth of clearance.
I think you are going to have problems getting 0.030" off the head without piston to head clearance problems. From memory you can only get around 0.015 to 0.020 off the head before you start to get too narrow on the piston to head clearance. You should be able to get a Cosworth or Cometic gasket around the 0.040" thickness which may just bring things back into tight but safe clearances.
good luck with it./
Chris.
I ordered a new tensioner/chain for the motor but it didnt turn up in time so I ran it with a used chain and tensioner. It had some slight rattle at idle which went away after I put the new chain/tension in. Changing the tensioner only didnt help, I had to also fit the new chain.
So from a chain slap perspective you should really fit a new chain and tensioner.
Your other consideration is head to piston clearance. You really need around 0.032 to 0.040" for the revs our engines do. The standard head gasket depending on supplier are around 0.032" thick so the easiest way to check clearance is to lay the head on the motor without any gasket and check you can turn it over without the pistons hitting the head. Ideally you want to make lots of measurements in different places but the basic check described will ensure you have at least the head gasket thickness worth of clearance.
I think you are going to have problems getting 0.030" off the head without piston to head clearance problems. From memory you can only get around 0.015 to 0.020 off the head before you start to get too narrow on the piston to head clearance. You should be able to get a Cosworth or Cometic gasket around the 0.040" thickness which may just bring things back into tight but safe clearances.
good luck with it./
Chris.
10-05-2010, 11:05 AM
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According to the manual the max one can remove is 0.008", the mininum height of the head has to be 4.132"
Resurfacing also changes - retards - the valve timing.
The top chain sprocket pitch circle diameter is (~) 95mm, it has 50 teeth.
pi * 95 ~ 298.45mm (= 360º)
0.008" = 0.20mm => 0.24º
0.030" = 0.76mm => 0.92º (That's a lot IMO)
About the timing chain tensioner: how would a 0.4mm (or 1.0mm, or 1.5mm) longer chain (or more slack on the coast side after resurfacing) make it not function or create a rattling chain?
One would think that's within operating design?
Resurfacing also changes - retards - the valve timing.
The top chain sprocket pitch circle diameter is (~) 95mm, it has 50 teeth.
pi * 95 ~ 298.45mm (= 360º)
0.008" = 0.20mm => 0.24º
0.030" = 0.76mm => 0.92º (That's a lot IMO)
About the timing chain tensioner: how would a 0.4mm (or 1.0mm, or 1.5mm) longer chain (or more slack on the coast side after resurfacing) make it not function or create a rattling chain?
One would think that's within operating design?
10-05-2010, 07:32 PM
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Thank you guys.
Heres what I am doing
I milled .030 off and I am compensating for that by using a cometic gasket thats .054 compared to the .030 on the OEM unit.
In theory that should be -.030+.024= -.006 which means that I removed.006 in total, I would assume thats not enough to really change things where it would matter much?
On a side note. I inspected the block with a machinist straight edge and a feeler gauge and found it to be within .006 off. I feel safe with the following plan:
The head gasket being thicker I should have more flexing and room for sealing if I were to torque the bolts around say 5-8ftlbs past spec. Would that make sence to you guys?
Heres what I am doing
I milled .030 off and I am compensating for that by using a cometic gasket thats .054 compared to the .030 on the OEM unit.
In theory that should be -.030+.024= -.006 which means that I removed.006 in total, I would assume thats not enough to really change things where it would matter much?
On a side note. I inspected the block with a machinist straight edge and a feeler gauge and found it to be within .006 off. I feel safe with the following plan:
The head gasket being thicker I should have more flexing and room for sealing if I were to torque the bolts around say 5-8ftlbs past spec. Would that make sence to you guys?
10-06-2010, 03:05 AM
#6
If the block is out of the car I would mill the deck the bare minimum to restore the surface. I've done around a dozen blocks and all of them had a head gasket imprint in the area between the bores.
If its still in the car then just mill the head and fit a new gasket. I wouldn't overtorque the bolts, they are done by angle anyway.
If its still in the car then just mill the head and fit a new gasket. I wouldn't overtorque the bolts, they are done by angle anyway.
10-07-2010, 06:01 PM
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block is still in the car and dont really feel like removing it
I looked at the block and it seems like I could slightly move the piston side to side very slightly but im assuming thats ok since the pistons are not supposed to be super tight on the sleeves?
another issue im having is I dont know if my valve seals are bad as the parts smell really bad like burnt oil OR if it was the head gasket that let oil in the pistons for a bit and thats why the pistons had lots of burned oil on the tops and in the intake manifold ports?
I looked at the block and it seems like I could slightly move the piston side to side very slightly but im assuming thats ok since the pistons are not supposed to be super tight on the sleeves?
another issue im having is I dont know if my valve seals are bad as the parts smell really bad like burnt oil OR if it was the head gasket that let oil in the pistons for a bit and thats why the pistons had lots of burned oil on the tops and in the intake manifold ports?
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