OK. I need to ask the pros some questions. First here is the setup:

JDM b16a with stock bottom end
JUN III cams and JUN cam gears
Head milled .030 with a 1 layer headgasket.

After looking further into the setup I became very worried about valve clearances with the cam/mill/hg combo. So I got the idea to pull the head and add a thicker headgasket. After some searching I found Cometic makes a hg that is .036in. This being ~.006 thicker than the stock gasket. So basically by adding .006 to the hg, I turn the actual mill of the head into .024. I feel this combo may be safer to run the JUN IIIs and allow me minimal use of the cam gears. Now by using the c-speed comp calc ( http://www.c-speedracing.com/h...c.php) with a stock JDM motor and that .036 hg, that gives me a CR of 10.21~1. Now by using another formula that uses the mill of the head, I get a CR of 11.13~1. Is this sufficient compression to make good use of the cams? Also, with a milled head, how should I adjust the gears to give me close to 0,0? How much can I adjust the gears until I run into problems? Maybe 3 degrees? 2? Now Cometic makes another hg that's .043, which will give me more clearance, but that will lower my compression to 10.89. Which I think is too low for those cams. Are there any other quality headgasket companies around? Any input is appreciated. I want to get this thing right so I don't ruin it the first time it goes into VTEC. BTW here is the other formula for the CR:

CCV = combustion chamber volume
CV = cylinder volume
MHV = milled head volume
CR = ( CCV + CV ) / CCV

To calculate CV (cylinder volume)
CV = (stroke) x (bore)^2 x (Pi/4)
CV = 7.7 cm x 8.1 cm^2 x .7853981633974
CV = 396.8 cc

To calculate CCV (combustion chamber volume)
Rearranging the equation CR = (CCV + CV) / CCV
CCV = CV / (CR - 1)
CCV = 396.8 cc / (10.2 - 1) = 43.1 cc

To calculate MHV (milled head volume)
(amount head was milled) x (bore)^2 x (Pi/4)
.030" mill off the head = .076cm
MHV = (0.076 cm) x (8.1 cm)^2 x .7853981633974 = 3.92 cc.

To calculate new CCV with milled head
CCV = CCV = 43.1 cc - 3.92 cc = 39.2 cc

To calculate new CR with milled head
CR = ( CCV + CV ) / CCV
CR = (39.2 cc + 396.8 cc) / 39.2 cc
CR = 11.12:1

 

Anyone?

 

you should have at least 11:1 comp for jun 3's...and as far as the cam gear question goes...don't adjust them until you get on a dyno....even then a lot of times the 3's like the stock settings

 

Well the way I figured using the two calculators, I'll be right at 11.1. Which why do I move the gears to adjust for the milled head? I know milling shortens the head therefore throwing cam timing off. I just don't knwo which way to turn them to get them back to stock.

 

Bump.

 

I USED to have a setup similar to yours... B16 bottom, B16 milled head, JUN III cams, Mugen HG. Needless to say that the valves wanted to become one with piston... That was a treat. So bottom line is ALWAYS clay your motor when using bigger cams to insure proper clearance.
You wanted to know about compression? 11:1 is nice.. better than 10.6, but it's still not enough to get the real potential out of the high lift/long duration of the JUN III. The bare minimum that I suggest for the cams would be about 12:1 on a unmilled head. You can also have the chambers welded and re-shaped, as well as use flat faced valves to give a slight compression bump. I know it sounds like $$ down the drain but you'll thank me if you do it. You'll also want to PNP the head and get a good exhaust/intake setup.
Cam gears can be finicky- You could set them to whatever we tell you, but it might not make the best use of power for your motor. I would really recommend using a dyno to set the gears. Good rule of thumb, don't go over 4 degrees in any direction. HTH!


Modified by advanracing62 at 9:39 AM 7/30/2003

 

I was wondering what kind of injectors/fuel pump/TB was needed for such a setup. i may be doing something very similar but in the 12:1 CR.. and don't want anything to blow up!

So if anyone has any input on a very good and very very reliable setup, that can be tuned perfectly through the vafc...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by advanracing62 &raquo;</TD></TR><TR><TD CLASS="quote">I USED to have a setup similar to yours... B16 bottom, B16 milled head, JUN III cams, Mugen HG. Needless to say that the valves wanted to become one with piston... That was a treat. So bottom line is ALWAYS clay your motor when using bigger cams to insure proper clearance.
You wanted to know about compression? 11:1 is nice.. better than 10.6, but it's still not enough to get the real potential out of the high lift/long duration of the JUN III. The bare minimum that I suggest for the cams would be about 12:1 on a unmilled head. You can also have the chambers welded and re-shaped, as well as use flat faced valves to give a slight compression bump. I know it sounds like $$ down the drain but you'll thank me if you do it. You'll also want to PNP the head and get a good exhaust/intake setup.
Cam gears can be finicky- You could set them to whatever we tell you, but it might not make the best use of power for your motor. I would really recommend using a dyno to set the gears. Good rule of thumb, don't go over 4 degrees in any direction. HTH!


Modified by advanracing62 at 9:39 AM 7/30/2003</TD></TR></TABLE>

What kind of power did that motor make? The head, IM, and TB have all been ported and polished as well. The valves are new ITR units. I'm going to use a dyno to tune the gears and the motor with Hondata. I'm just trying to find out where to set them before I fire up the motor for the first time too offset the difference caused by the milled head. Who are some more headgasket companies who maybe make one that .025", a little less than stock? I'd trying to find a happy medium between a thin headgasket and milled head without swallowing a valve. I'm pretty sure I'm going to go ahead and clay the motor once I find a little thicker headgasket than the 1 layer on there now.

 

Bump for an answer to my question.

 

'nother bump.