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Discussion Starter #1 (Edited)
I have my head at the machinist right now, I called him up today and I asked if he could shave a little extra to bump the compression up a little. He asked me how much.. and I have no clue.. kinda left me with the deer in the headlights look you know what I mean.. so any help/knowledge would be greatly appreciated! thanks!

EDIT:
I guess I should give some background info, huh?

JDM B20A
B18a1 Intake cam
B21 Exaust cam
CAI
DC headers
as far as I know, stock bottom end.
 

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Ya they said it. And if things don't work out, you possibly can't shave the head again in the future.

You could get a port and polish to improve it since it's already at the shop. It might be costly but this is your chance to have it done. There are very nice gains to be had with P&P and other mods combined. Will you be getting a tunable ECU for it?
 

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Discussion Starter #5
eventually I would like to go with a megasquirt, but for now I'm staying stock ECU.
 

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just shave all of it off. hopefully it will grow back evenly. i think bald is a good look but its too cold for that now. oh wait. my bad. disregard this
 

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yeah it does.

but mega squirt is a very involved ecu setup that basically requires you to rewire the whole engine bay...

just stick with the OBD-1 conversion and get a p04 chipped by chrome.

and just tell your machinest to go easy on the shave, but definately take enough of to notice it.

sinceyou already have the B20a you already have higher compression pistons than those B20a5 guys... next step is to shave the head as far as cheapness goes, but you would definately benefit from getting a port and polish too.


megasquirt.. lol
sounds dirty.
 

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If I wouldn't raise the compression by cutting the head.
I assume you mean it won't raise it enough to be worth much.

Remember, you're altering the height of the head... which will mean, you're going to need cam gears to properly set your cams.
yup. You don't want to mess with the height of those cam gears vs the crank gear... :emthup:


Shave the head the BARE minimum to get it flat. What happens if you pull the head off again and have to mill it more? you're boned and you have to find a new head.
Milling the head is not a good way to increase compression. Get higher compression pistons if you want it that bad.
 

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how much and what stages are there in port and polish? is there a stage 1, 2, 3 etc... and how much does it usually run?
I'm not sure how it is classified as (stages). Sometimes the shop can tell you how much meat they remove. Most importantly, the imperfections are removed. Honda heads, or at least 3rd gen heads have casting flaws.

You shouldn't need a whole lot of meat removed. If the head is ported too much it can hurt performance. When it is finished it should look smooth and shiny.
 

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I'm not sure how it is classified as (stages). Sometimes the shop can tell you how much meat they remove. Most importantly, the imperfections are removed. Honda heads, or at least 3rd gen heads have casting flaws.

You shouldn't need a whole lot of meat removed. If the head is ported too much it can hurt performance. When it is finished it should look smooth and shiny.
thanks, how much does it usually run? $200, $500, $1000, I understand it various from shop to shop, but what's an average medium?
 

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if this is a b20a3 head only do .003/.005 thousandths to clean up the head.because you will need a adjustable cam gear and they dont make them for the b20a3.if this is a b20a5 .012 thousandths is all i would remove for a street motor but it is noticeable.you will need adjustable cam gears,for every .012 you mill off you will need to advance the gears 1*.also with haveing the adjustable cam gears you can move them around to find even better power.

this is a b20a3 head i did for my self for the daily driver,im ready to install the motor tomorrow.







 

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if this is a b20a3 head only do .003/.005 thousandths to clean up the head.because you will need a adjustable cam gear and they dont make them for the b20a3.if this is a b20a5 .012 thousandths is all i would remove for a street motor but it is noticeable.you will need adjustable cam gears,for every .012 you mill off you will need to advance the gears 1*.also with haveing the adjustable cam gears you can move them around to find even better power.

this is a b20a3 head i did for my self for the daily driver,im ready to install the motor tomorrow.







The B20a3 has adjustable cam gear options. They are not advertised as compatible with the B20a3. I, with the help of Bob_nova and some other members found that some other SOHC Honda motors have the same cam gear. And now I can't find the PM with that info...

The SOHC F22 from a 4th gen Prelude should be compatible with the B20a3. I think that was it.
http://www.google.com/products?q=F22+prelude+cam+gear&btnG=Search+Products&hl=en&show=dd&scoring=p
 

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if this is a b20a3 head only do .003/.005 thousandths to clean up the head.because you will need a adjustable cam gear and they dont make them for the b20a3.if this is a b20a5 .012 thousandths is all i would remove for a street motor but it is noticeable.you will need adjustable cam gears,for every .012 you mill off you will need to advance the gears 1*.also with haveing the adjustable cam gears you can move them around to find even better power.

this is a b20a3 head i did for my self for the daily driver,im ready to install the motor tomorrow.
.003/.005 thousandths, or 3/5 thousandths?

there is a HUGE difference..
 

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.003 is to be the mimimum and .005 is the maximum to be machined from the head.your machinest will know what i am talking about.

i was not aware of an adjustable cam gear for the shoc.i knew JG years ago made them from your old cam gear but he dosent do this anymoor.i have suspected that the d15/d16 shoc cam gears were the same but i havent had them beside each other to see.
 

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no, you said .003-.005 THOUSANDTHS.
that is wayyyyy different than 3-5 thousandths..

.003/.005 thousands is 3-5 thousandths of 3-5 thousandths.
thats 3-5 millionths.
 

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3-5 thousandths is the same as .003/.005 its just that the desamol point has been added in its proper place.i have been a machinest for over 28yrs,so dont tell me i dont know what im talking about!
 

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no, you said .003-.005 THOUSANDTHS.
that is wayyyyy different than 3-5 thousandths..

.003/.005 thousands is 3-5 thousandths of 3-5 thousandths.
thats 3-5 millionths.

.3 = tenths
.03 = hundreds
.003 = thousandths
.0003 = millionths.


Biscuit's information is accurate.


To the OP: Have it taken down enough for it to be flat.
 
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