Maximum Head Milling in Thousandths

[BoomerBob]

I'm curious as to what the maximum the heads can be milled to until they are out of spec.

Anyone know off the top of their head? (Pun intended)

The machine shop had to mill 11 thousandth off mine to get them flat again.

 

[pauldub]

From the FSM:

4. INSPECT CYLINDER HEAD (a) Inspect for flatness. Using a precision straight edge and feeler gauge, measure the surfaces contacting the cylinder block and manifolds for warpage. Maximum warpage: 0.10 mm (0.0039 in.) If warpage is greater than maximum, replace the cylinder head.


Toyota doesn't seem to think anyone is going to machine the heads to make them flat again.

 

[BoomerBob]

From the FSM:

4. INSPECT CYLINDER HEAD (a) Inspect for flatness. Using a precision straight edge and feeler gauge, measure the surfaces contacting the cylinder block and manifolds for warpage. Maximum warpage: 0.10 mm (0.0039 in.) If warpage is greater than maximum, replace the cylinder head.


Toyota doesn't seem to think anyone is going to machine the heads to make them flat again.

Well that's interesting and of course we do mill the heads here in the USA.

Thank you sir!

 

[19963.4lsr5]

It’s against the EPA regulations to mill heads to make them flat again. It raises the compression which raises the NOX emissions.


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[gamefreakgc]

It’s against the EPA regulations to mill heads to make them flat again. It raises the compression which raises the NOX emissions.


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It also can increase power output, which is also illegal here in California.

If you want to buy a new car with loads of power (and forced induction I might add) and possibly worse emissions though go right ahead, the state is very happy to make their 8.25% in sales tax though!

 

[STI_MECE]

Just triple stack your gaskets or make one big gasket lol

 

[plcfcng]

I live in Riverside Co. California I have had 3 sets of head milled for straightness. At a Shop in San Marcos. :guitar2:

 

[davidch]

The side effects

One of the oft-stated benefits of the 5VZ-FE engine is that it's a non-interference engine: if the timing belt breaks and a camshaft stops with a valve at maximum lift, then the piston won't strike the valve.

So how close is the valve to the piston at that point? There has to be some amount of milling that would make the engine an interference engine.

As to raising the compression ratio, I was curious as to how much of an effect 0.011" would have. Calculations below:

 

[19963.4lsr5]

One of the oft-stated benefits of the 5VZ-FE engine is that it's a non-interference engine: if the timing belt breaks and a camshaft stops with a valve at maximum lift, then the piston won't strike the valve.



So how close is the valve to the piston at that point? There has to be some amount of milling that would make the engine an interference engine.



As to raising the compression ratio, I was curious as to how much of an effect 0.011" would have. Calculations below:

If I would have known that .015 would be close to 10:1 I’d have had them decked 15 thou an put a Singh’s Grove in the head. He decked it but didn’t know how much. “Just enough to make it flat”


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[BoomerBob]

As it turned out; all my work (and money wasted) was for nothing. The rings are shot on 3 cylinders. The extra tools I can maybe reuse one day but the $400 to rebuild the heads was a complete waste of money.

I ended up buying a remanufactured American long block with zero miles for about $1700 plus $400 core charge which I hope to get back. An expensive hit but I should end up with an 01 4R that runs longer than me.

 

[BoomerBob]

One of the oft-stated benefits of the 5VZ-FE engine is that it's a non-interference engine: if the timing belt breaks and a camshaft stops with a valve at maximum lift, then the piston won't strike the valve.

So how close is the valve to the piston at that point? There has to be some amount of milling that would make the engine an interference engine.

As to raising the compression ratio, I was curious as to how much of an effect 0.011" would have. Calculations below:

I wonder if the higher CR the regular gas would still be enough. Is the MAF and computer smart enough to advance or retard the timing as needed for this higher CR?

 

[BoomerBob]

If I would have known that .015 would be close to 10:1 I’d have had them decked 15 thou an put a Singh’s Grove in the head. He decked it but didn’t know how much. “Just enough to make it flat”

What's a Singh's Grove?

 

[19963.4lsr5]

What's a Singh's Grove?

Google it and ST (surface tension) valve mod. I did both plus decking the head to get 10:1CR to my old 1996 S Series Saturn.

The head picture doesn’t have the Grove in it when I took the picture.


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[alumarine]

Singh grooves not Singh's grove

 

[gamefreakgc]

I wonder if the higher CR the regular gas would still be enough. Is the MAF and computer smart enough to advance or retard the timing as needed for this higher CR?

Only if the engine starts to knock will it pull timing. The MAF is not very smart, it only adds fuel based on how much airflow is coming in, which I'm guessing will be the same since it's not adding displacement (actually losing a tiny bit) but instead just increasing compression.

 

[BoomerBob]

Only if the engine starts to knock will it pull timing. The MAF is not very smart, it only adds fuel based on how much airflow is coming in, which I'm guessing will be the same since it's not adding displacement (actually losing a tiny bit) but instead just increasing compression.

Knock or ping I would imagine.