I bought a set of SRP pistons (3.209" bore) and compression height of 1.045". I'm using a b20a crankshaft (95 mm stroke) as opposed to the LS/B20 (89mm)/GSR/ITR (87mm). This is all part of the Eagle Stroker Kit. I just wanted to know if I'd have Piston to Valve clearance issues if I use Skunk2 Stage 3 camshafts (NOT PRO 3s). Thanks.

 

Best way to find out is to clay the engine. I wouldn't trust the money you spent on parts to someone's guess on the internet. 99.9% of the engine problems on this site stem from people doing what other people told them would work rather than actually checking things out themselves.

Any time you get into the stage 3's with higher lift you have to be concerned with clearance issues. Ask the manufacturer of the cam what they suggest for clearances. If your scared that your going to smack a few valves adjust your clearance to 0.030" And if you do go over your clearances you can always flycut the pistons to fit your lift (larger/deeper valve reliefs). There should be more than enough material on them to remove a 0.010" or two. Most off the shelf aftermarket pistons are produced on the safer side of the clearances anyway.

That's just my 2¢ worth

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GhostAccord &raquo;</TD></TR><TR><TD CLASS="quote">Best way to find out is to clay the engine. I wouldn't trust the money you spent on parts to someone's guess on the internet. 99.9% of the engine problems on this site stem from people doing what other people told them would work rather than actually checking things out themselves.

Any time you get into the stage 3's with higher lift you have to be concerned with clearance issues. Ask the manufacturer of the cam what they suggest for clearances. If your scared that your going to smack a few valves adjust your clearance to 0.030" And if you do go over your clearances you can always flycut the pistons to fit your lift (larger/deeper valve reliefs). There should be more than enough material on them to remove a 0.010" or two. Most off the shelf aftermarket pistons are produced on the safer side of the clearances anyway.

That's just my 2¢ worth </TD></TR></TABLE>

He's right, clay the engine for p-v clearance (don't forget to lock in the VTEC). But with the Skunk2 stage 3's, valve to valve clearance can be an issue. We used to use these cams in 2002 for the World Challenge Touring car (road racing) series. When the cams first came out, everyone was caught by surprise of how easily the valves came EXTREMELY close to each other when adjusting for cam timing on the dyno. Unfortunately, Clay won't tell you your valve to valve clearance.

hope that helps

 

im a noob to engine building.

when is valve to piston clearance measured in the engine building procesS?

 

as soon as the short block and head are fully toleranced and built then the measurement games can begin

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lubo_25 &raquo;</TD></TR><TR><TD CLASS="quote">as soon as the short block and head are fully toleranced and built then the measurement games can begin </TD></TR></TABLE>

valve to piston clearance is done on every built motor regardless if its turbo or all motor correcT?

 

for me personally it does not matter which type of induction the engine will be going through everything is always double checked and logged within the blueprints...period

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MeanGreenMachine &raquo;</TD></TR><TR><TD CLASS="quote">

valve to piston clearance is done on every built motor regardless if its turbo or all motor correcT?</TD></TR></TABLE>

will a helms repair manual for my specific vehicle give me the specifications of piston to valve clearance for my engine/vehicle?

wait - is valve to piston clearance adjusted by doing a valve adjustment?


Modified by MeanGreenMachine at 3:40 PM 3/19/2008

 

no...helms do not have those specifications due to the fact when you do get into those types of tolerances youre pretty much building a motor from scratch now...helms only have tolerances for rebuilding back to factory standards...unless they've changed things now...I only use honda manuals anyway so it does not concern me too much what they put in their specs...

no...valve adjustments have a set lash clearance and must NOT exceed factory spec by any means...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lubo_25 &raquo;</TD></TR><TR><TD CLASS="quote">no...helms do not have those specifications due to the fact when you do get into those types of tolerances youre pretty much building a motor from scratch now...helms only have tolerances for rebuilding back to factory standards...unless they've changed things now...I only use honda manuals anyway so it does not concern me too much what they put in their specs...

no...valve adjustments have a set lash clearance and must NOT exceed factory spec by any means...</TD></TR></TABLE>

even if u clay the motor to figure out your piston to valve clearance, how do you adjust it?

 

Parts way;
Thicker head gasket for more clearance thinner for tighter. You could buy a different set of pistons with the specs that you need. Those are a few of the easy ways to get a change in clearances. For example, Wiseco recommends the use of a 0.40" crush hight head gasket for some of there domed pistons to insure a 0.030" P2V clearance. I know this because I am currently doing some research into this very topic.

The machinists way;
you could have a flycut job done on the pistons if the clearance is to small and you need to make more room. Flycutting utilizes a special tool that is made specifically for cutting larger or deeper valve reliefs into the tops of pistons.

If you need to close the gap you could mill the head and/or block a few thou to close that gap.

 

this is what i HEARD, valve to piston clearance is done more on high compression, ALL MOTOR vehicles due to the dome shape of most high compression pistons.

piston to valve clearance is not done so much on turbo motors due the pistons having a flat surface.....can anyone confirm?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MeanGreenMachine &raquo;</TD></TR><TR><TD CLASS="quote">this is what i HEARD, valve to piston clearance is done more on high compression, ALL MOTOR vehicles due to the dome shape of most high compression pistons.

piston to valve clearance is not done so much on turbo motors due the pistons having a flat surface.....can anyone confirm?</TD></TR></TABLE>

Turbo engines typically have less VtoP issues because the cams tend to be less aggressive with less overlap.

 

ALL ENGINES NO MATTER WHAT. Should have the clearance checked. It doesn't matter if it's a 1320 N/A or FI drag car or your mothers grocery getter. You should always check the clearances to ensure they are within tolerance during any engine build.

 

When someone says clay the engine, is the process just putting clay on top of the pistons, assembling the motor, torquing everything to spec and then disassembling it again, then checking your clearances?

Where can this clay be purchased at?

 

you can use play-doh or silly putty just make sure you put some wd-40 on the top side to prevent the valves from sticking on to the clay...

to check your clearances though you need to rotate the motor over for your valves to actually kiss the clay pieces on your piston dome angles and piston flats then use a scale or digi calipers to determine your distances...its hard for me to explain on here its something that has to be shown in person

last time i checked i think c speed racing has it on their website...



Modified by Lubo_25 at 6:42 AM 3/21/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lubo_25 &raquo;</TD></TR><TR><TD CLASS="quote">
last time i checked i think c speed racing has it on their website...</TD></TR></TABLE>

ill search that site and see what i can find out

thanks!

 

you probably dont have to check piston to valve clearance if you're a) not gonna play with cam timing, b) not getting an aggressive camshaft. even then, i'm sure the cam manufacturers took this into consideration when designing lift and duration. just be sure you have your cams timed dead on (by degreeing them) and you'll be fine.

 

FOUND IT!

http://www.c-speedracing.com/h...y.php

 

Do what you want....I say do it to be on the safe side no matter what. If you loose the art of measuring you'll pay in the long run. It's well worth it even just to get the practice. If your a DIY and you are rebuilding a motor stock...giggle giggle.....sooner or later you'll be going bigger and you'll need the practice!

Oh and one more note...Your cams are timed "dead on" then you have them on the dyno and your adjusting them 1 or two degrees and .......WHACK you hit a piston! Well this could have been avoided if you had clayed them for the most + & - degrees that you planed on going with your timing before you even started the engine. Am I alone in thinking this????


Modified by GhostAccord at 12:41 PM 3/21/2008

 

no you're totally right. but i also qualified my statment by saying <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mikey3000 &raquo;</TD></TR><TR><TD CLASS="quote">you probably dont have to check piston to valve clearance if you're a) not gonna play with cam timing, </TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GhostAccord &raquo;</TD></TR><TR><TD CLASS="quote">Do what you want....I say do it to be on the safe side no matter what. If you loose the art of measuring you'll pay in the long run. It's well worth it even just to get the practice. If your a DIY and you are rebuilding a motor stock...giggle giggle.....sooner or later you'll be going bigger and you'll need the practice!

Oh and one more note...Your cams are timed "dead on" then you have them on the dyno and your adjusting them 1 or two degrees and .......WHACK you hit a piston! Well this could have been avoided if you had clayed them for the most + & - degrees that you planed on going with your timing before you even started the engine. Am I alone in thinking this????

Modified by GhostAccord at 12:41 PM 3/21/2008</TD></TR></TABLE>

from looking at the write up, it looks like when u clay the motor your setting the cam gears to the maximum and minimum degrees to see how close you come to hitting the pistons, is that correct? if your maximum # of degrees on your cam is 5 and u set it at 5, and your valves are hitting the pistons, then youd reduce the amount of degrees on the cam until you have the desired piston to valve clearance?

am i correct in my thinking?

p.s. - if you are using a stock camshaft and cam gear, but have a built bottom end, the claying process and checking of the piston to valve procedure still needs to be performed correct?

 

Yes, when you do claying for +degree and -degree cam timing you are trying to find your max degrees + & -. Therefore you will know before you even put your car on the dyno what your limits are for cam timing.

As for a stock cam, gear and valves and pistons you should be able to install it and forget about it. But as I said it's always better to check it. Practice makes.......better! I'm not going to say prefect because it takes more than 2 or 3 builds to be perfect.... more like years and years of experience to get even close to perfect.

Call me **** but I don't mind taking an hour or two to take measurements.

 

every set of pistons will come with a spec sheet specifying the desired amount of piston to valve clearance correct?

 

Any reputable piston manufacture should yes. If they don't give them a call and they should be more than happy to give you the info. If they don't want to give you the info send the pistons back and buy from someone else!