my piston sticks out of the deck by 0.030. it is also over bore to 89mm too, making it around 0.112 larger the head chamber. when i rotate the crank (without head gasket) it lifts the head. since stock cometic thickness is 0.030, can i just get a custom gasket of 0.060 to be safe or do i have to mill the piston or round out the chamber?

 

You also need to account for metal expanding at temperature, as well as piston to valve clearance.

You'll need to enough clearance to assemble it, then clay it.

Did you not do the math and see this coming in advance?

 

let me guess, another hyrbrid build that wasnt thought through . if you mill the pistons you are also going to have to do some work on the valve reliefs. find the six sigma racing thread and read that through

 

use an 0.070 gasket, you want around 0.040 piston-head clearance when the piston sticks out.

when the piston sticks out its slightly less stable than when it dosnt, so it will rock a little more at tdc, requiring a little more clearance. and most oem stuff has the piston 0.005-0.010 IN the hole making for ~0.040 piston-head with a 0.030 gasket

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bluedlude &raquo;</TD></TR><TR><TD CLASS="quote">let me guess, another hyrbrid build that wasnt thought through . </TD></TR></TABLE>

That's what it sounds like.

What block, crank, rods, pistons are you running?

 

i'm using a h23 crankshaft and h23 rods w/ wiseco pistons (12.1 cr). for those who don't remember:

+

+

+ H-beam rods from blueprintmfg.com
i had a local performance machine shop install and balance the block. sorry, don't have any update photos of the work because my digi cam broke.
so let me get this right. get the 0.070 head gasket, and then clay for piston to valve clearance? throw me some suggestions or ideas.

 

Oh I remember now... we told you not to do that and you did anyways because we were wrong.

 

lol

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ge_itr &raquo;</TD></TR><TR><TD CLASS="quote">my piston sticks out of the deck by 0.030. </TD></TR></TABLE>

There are a few different ways to deal with this. Check out this thread:

https://honda-tech.com/zero...26776

and the H23/VTEC thread. Good luck.

 

you guys are silly.
throw a .060 gasket on and your good to go. what compression numbers are you shooting for?

 

are those pistons for the h22. if so then your compression is a point higher.
so with a .060 gasket you will be at 12:1

what cams? if bigger than pro1 I would clay

 

So you're actually using that crank?

 

knowledge at others expence is what h-t is all about

 

what are the dome specs of that piston? what is your target compression? If you knew the block height that would help too, sounds like its been decked slightly.

JDogg is right on the .07" gasket. You'll end up with a much larger squish band then desired, but being that your piston is bigger then the diameter of the combustion chamber you'll want to be on the safe side. Might want to do some deburring there too of that edge of the combustion chamber thats going to be hanging over.

 

From the look of it he should be running E85 or 110 octane when he gets it assembled.


That crank's been cut on a bit hasn't it?





Good luck dude.

Pirate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rosko &raquo;</TD></TR><TR><TD CLASS="quote">what are the dome specs of that piston? what is your target compression? If you knew the block height that would help too, sounds like its been decked slightly.

JDogg is right on the .07" gasket. You'll end up with a much larger squish band then desired, but being that your piston is bigger then the diameter of the combustion chamber you'll want to be on the safe side. Might want to do some deburring there too of that edge of the combustion chamber thats going to be hanging over.

</TD></TR></TABLE>

how do i measure the dome spec and block height after it's been installed? aiming for 12.0:1 CR. i've searched but still skeptical on how to deburr. any source on that?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred &raquo;</TD></TR><TR><TD CLASS="quote">

That crank's been cut on a bit hasn't it?

Pirate </TD></TR></TABLE>
not sure. i bought the crankl like this. but it's been measured and balanced before installation.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by alterdcreations &raquo;</TD></TR><TR><TD CLASS="quote">are those pistons for the h22. if so then your compression is a point higher.
so with a .060 gasket you will be at 12:1

what cams? if bigger than pro1 I would clay</TD></TR></TABLE>

i got the skunk2 pro 2's.

.060 or .070?

 

The dome spec should be on the box they came in (ie.. 6cc's...8cc's etc.) otherwise its a pita to measure now.

Its gonna be hard to measure the block now that its all put together, thats one of several things you want to have recorded when you build a motor BEFORE its together but if you're .03" measurement is correct then it sounds like you've had roughly ~.01" removed from the deck. Still need that piston spec though.

 

quote from flyrod: Pirate cut his chambers to handle pistons sticking out of the deck, and Six Sigma Racing cut the pistons down. A thick gasket should achieve the same thing.

to cut or not to cut?

 

i'll look for that dome spec tomorrow.

 

I prefer Pirates way myself opposed to cutting pistons. BUT you need to figure out your compression first because odds are you are waay high as is and will most likely have to lower it with a thicker gasket. Theres some pics later on in my thread of where I opened up my Alaniz head for the 88mm pistons I was using and heres a thread from along time ago where I did it with the CNC machine and went all the way up to 90mm on a chamber just for practice. The one I did recently on my Alaniz head was done just like Pirates pic and then blended by hand with a die grinder.

 

dome spec: Honda 4v dome + 6.5cc strutted 89mm
Compression height: 1.2180
bore: 3.5039
kit #: k572m89
piston(s) #: 6572m89
suggested clearance: 0.0025

what do you guys think about the options: .070 gasket without cut. OR .060 gasket with chamber cut.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred &raquo;</TD></TR><TR><TD CLASS="quote">From the look of it he should be running E85 or 110 octane when he gets it assembled.

That crank's been cut on a bit hasn't it?

Good luck dude.

Pirate </TD></TR></TABLE>

I would say it's more like someone actually attacked it with a 7" right angle grinder and didn't wear any eye protection.

Good luck anyway. You're going to need it.

 

If you're going to have the pistons modified, you'll need to tear down the block anyway.

You really should measure the dome directly. Same goes for the combustion chamber. Without doing that, you're really just making an educated guess when it comes to the static CR.

Are you doing this as a final build? Or is this just the mock up? I hope you were smart enough to be in the mock up stage, and you haven't torqued everything to spec yet.

Where is the contact taking place? On the quench pads?

If I were you, I'd do a mock up with two used head gaskets to see where you're at. A compressed head gasket is roughly 0.026" thick so that'll be a tad less than 0.060". Measure all the clearances and see where you stand. Making a decision to modify the pistons or use a thick headgasket without doing a simple mock up is stupid, IMO.