Stock Head thickness

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Nativo
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Stock Head thickness

Postby Nativo » Wed Feb 04, 2015 7:26 am

Need to know the original head thickness of the 16v head from top to bottom in order to find out how much my engine's head it has been shaved. if anyone knows I'll appreciate your sharing.


Thanks,
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yoshimitsuspeed
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Re: Stock Head thickness

Postby yoshimitsuspeed » Wed Feb 04, 2015 12:19 pm

Nativo wrote:Need to know the original head thickness of the 16v head from top to bottom in order to find out how much my engine's head it has been shaved. if anyone knows I'll appreciate your sharing.


Thanks,

This will be a little different from motor to motor and is somewhat of an extraneous measurement and would not have had as tight machining tolerances.
I would be more concerned with your combustion chamber volume.

davew7
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Re: Stock Head thickness

Postby davew7 » Thu Feb 05, 2015 7:10 am

A typical stock Big Port head will have a chamber volume around 38.7 - 39cc. As a rough guide .64cc reduction for every .005" milling. Dave W

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Nativo
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Re: Stock Head thickness

Postby Nativo » Thu Feb 05, 2015 8:01 am

yoshimitsuspeed wrote:
Nativo wrote:Need to know the original head thickness of the 16v head from top to bottom in order to find out how much my engine's head it has been shaved. if anyone knows I'll appreciate your sharing.


Thanks,

This will be a little different from motor to motor and is somewhat of an extraneous measurement and would not have had as tight machining tolerances.
I would be more concerned with your combustion chamber volume.


Thanks, I base my question on the (common)understanding that our engines more or less increases in compression ration at the same rate of head shaving ie; .1mm shaving = .1 increase in CR.
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Re: Stock Head thickness

Postby yoshimitsuspeed » Thu Feb 05, 2015 9:08 am

davew7 wrote:A typical stock Big Port head will have a chamber volume around 38.7 - 39cc. As a rough guide .64cc reduction for every .005" milling. Dave W



Where did you get that number?
The only persona experience numbers put it very close to 36CC.
Oldskewltoy has measure more heads than anyone else I have talked to and claims 36-37, usually on the lower end of that.
I have measured a couple heads that were dang close to 36 to just a tad over.

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Re: Stock Head thickness

Postby yoshimitsuspeed » Thu Feb 05, 2015 9:10 am

Nativo wrote:
Thanks, I base my question on the (common)understanding that our engines more or less increases in compression ration at the same rate of head shaving ie; .1mm shaving = .1 increase in CR.


I don't remember hearing anything like this.
Easy enough to test the theory though.
http://www.csgnetwork.com/compcalc.html

http://www.matrixgarage.com/content/4ag ... ormation-0

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oldeskewltoy
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Re: Stock Head thickness

Postby oldeskewltoy » Thu Feb 05, 2015 10:53 am

Stock uncut head thickness is 116mm(4.5669")

edit - added photo
Image

A 1mm cut will get you down to about 33cc-33.5cc, a cut of .010" will drop volume by about 1/2cc-3/4cc

Stock chamber is 36cc... as comfirmed by the TRD Bible.

Image
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Illegal_Garage
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Re: Stock Head thickness

Postby Illegal_Garage » Mon Feb 16, 2015 1:54 am

i'd recommend getting a nice set of calipers
either Starret or Mitutoyo brand
not some junk harbor freight brand
veneer > dial > digital

or you can borrow some from your local machine shop (bring beer)

if you have not already have got your hands on the factory service manual
I'd also recommend you pick one up
it can be found on line for free download

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Re: Stock Head thickness

Postby yoshimitsuspeed » Mon Feb 16, 2015 9:43 am

If you have buckets of money then sure buy a nice set of calipers.
I do not believe they are a worthwhile investment for the average DIYer and questionably moreso for general machine work.
I have inspected dozens of the cheap calipers over their lifespan.
They do wear out a little quicker but when they do you just toss them in your tool box and get a new set for precision work.
Regular inspection is the most important thing. A set of $15 calipers regularly inspected will be more trustable and more accurate than neglected Mitutoyos.
More importantly any caliper is only going to be god to about .001" or .025mm.
People often rely on calipers for much more precise measurements anyway. If the difference between cheap calipers and expensive is really worth worrying about then you should really be using a mic anyway.

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Re: Stock Head thickness

Postby Illegal_Garage » Tue Feb 17, 2015 2:00 am

Nice dial calipers can be had under $100

Anywho like i said it's best to just go ask someone else to do the measuring then

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Re: Stock Head thickness

Postby davew7 » Tue Feb 17, 2015 5:55 am

The 38.7-39cc is "CHAMBER" volume not HEAD volume. Using a standard head gasket, not TRD gasket and with the pistons set .001" to .003 below the deck for determining the compression ratio on a stock big port. Dave W

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Re: Stock Head thickness

Postby yoshimitsuspeed » Tue Feb 17, 2015 8:19 am

Illegal_Garage wrote:Nice dial calipers can be had under $100

Anywho like i said it's best to just go ask someone else to do the measuring then

Max


My point is that the average enthusiast can make that money go a lot further if spent wisely.
For about the same price you could buy a cheap pair of calipers, and a half decent 1-100 mm mic set which puts you far ahead of the precision of good calipers.
Even better is it should come with a set of gauge blocks which will allow you to inspect your cheap calipers and make sure they stay in spec.
http://www.ebay.com/itm/Fowler-Metric-O ... 2c6437164f
Here is a set even cheaper.
http://www.ebay.com/itm/Fowler-Mic-Set- ... ls&vxp=mtr
For just another $50 you could get a 100-125mm mic to measure your head and keep in your tool box for other stuff.
http://www.ebay.com/itm/Blue-Point-MIC5 ... 20f23b641c

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Re: Stock Head thickness

Postby yoshimitsuspeed » Tue Feb 17, 2015 8:21 am

davew7 wrote:The 38.7-39cc is "CHAMBER" volume not HEAD volume. Using a standard head gasket, not TRD gasket and with the pistons set .001" to .003 below the deck for determining the compression ratio on a stock big port. Dave W


Chamber volume and head volume is the same thing. I have never heard it include the other variables like HG or deck. Those should be calculated separately.

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Re: Stock Head thickness

Postby oldeskewltoy » Tue Feb 17, 2015 8:27 am

yoshimitsuspeed wrote:
davew7 wrote:The 38.7-39cc is "CHAMBER" volume not HEAD volume. Using a standard head gasket, not TRD gasket and with the pistons set .001" to .003 below the deck for determining the compression ratio on a stock big port. Dave W


Chamber volume and head volume is the same thing. I have never heard it include the other variables like HG or deck. Those should be calculated separately.


Correct me if I'm wrong.... low comp piston has a volume of 3.8cc, head is 36cc so we are @ nearly 40cc without the headgasket volume, or deck volume.....
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

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Re: Stock Head thickness

Postby yoshimitsuspeed » Tue Feb 17, 2015 9:07 am

oldeskewltoy wrote:
yoshimitsuspeed wrote:
davew7 wrote:The 38.7-39cc is "CHAMBER" volume not HEAD volume. Using a standard head gasket, not TRD gasket and with the pistons set .001" to .003 below the deck for determining the compression ratio on a stock big port. Dave W


Chamber volume and head volume is the same thing. I have never heard it include the other variables like HG or deck. Those should be calculated separately.


Correct me if I'm wrong.... low comp piston has a volume of 3.8cc, head is 36cc so we are @ nearly 40cc without the headgasket volume, or deck volume.....


I don't think his calculation factors dome/dish but I am unfamiliar with trying to do it this way lol.
I would agree though that if you are going to call the gasket, deck etc all combustion chamber volume that you might as well include dome/dish as it's technically part of the area where combustion takes place.

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