I've been told that some camps push the valves down to far in a NA situation & hi comp pistons would slap the valves. Oviously this is less likley in low comp piston setup due to the top of the piston being lower when at TDC. What i would like to know is what math do i have to do to find out if i can run a certain cam in the motor without having failure.

More or less, i've got some Skunk2 Stage 2's (Intake 12.3 mm / 266 @ 1mm Exhaust 11.8 mm 262 @ 1mm) and i wanna know if they would work well with my boosted application. Pistons in this situation would be CP's (SC7021) 84.5mm / Piston to Deck -11.8 / Comp = 9.2:1

Any insite on this would be great, meanwhile i'll continue googlology!

Thanks

 

suggestion was just made to use some wax and put it all together with the wax in the cylinder & then rotate it by hand then pull apart & measure the wax if the piston doesn't hit the valve.

I Really don't wanna have to do it this way. Someone out there has to have equasion to figure this out with some math instead. I mean i understand that the wax thing would work but i don't wanna have to find out like that if i don't have to. Especially when that doesn't factor in any type of variable difference for rotation by hand vs a 10k rev or something of the sort.

 

you also need to worry about what your valve springs will handle. most low comp pistons will take any cams

 

using supertech double valve springs & ti retainers. Shouldn't have a problem there. It seems that these cams are much more agressive than the Stock GSR cams that i also have sitting here & i'm thinking it would be a waste not to use them when they are just sitting around.

 

Clay the motor and degree the cams in. There is no guess work there. You will know exactly what your piston to valve clearnce is and where your cam is in relation to your pistons

 

Just to get you started, use a long dial indicator and check springs (low tension springs).





You also need to check clicking clearance (Valve 2 Valve).

 

nice to see someone actually use the degree wheel. most people dont even know what the hell that is.

to the op if your going to clay the motor and its vtec. be sure to engage the vtec when rotating the assembly.

 

thanks everyone for the input thus far. I really had no clue what to do to test this so it's very informative.

Thanks

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman &raquo;</TD></TR><TR><TD CLASS="quote"> be sure to engage the vtec when rotating the assembly.</TD></TR></TABLE>

how would you go about doing this?

 

It's really overwhelming the first time you learn how to check piston to head, piston to valve, valve to vavle, degreeing the cam and checking overlap the first time, Especially on a Vtec motor because you have to check all these while Vtec in engaged. Once you know all this info....you know exactly whats going on.

It's alot easier if someone teaches you the first time. Trying to do it after someone explains it is very hard.

 

I'd just like to know how to activeate the vtec lobe while the head is off the car. I'm assuming theres something in the solinoid area, i've just yet to look.

 

heres a write up on doing cam degree. http://www.skunk2.com/camshaft_tech.php

 

check out mike belben's fixture
http://www.newenglandhondarebuilders.com/

 

I don't remember what size ball bearing I used, but you pop out the short pin and put the ball bearing behind it before assembling the rockers. It will lock all three rockers.