i was reading around on installing valves on my own thread and others... and i was said sometimes they come up with bad sealing problems if you dont lap the valves with a tool and a compound before you install them.... what is lapping the valves and how would you go about doing it, i just got my head back from the shop... 3 angle valve job and a pocket port i was wondering if i would have to lap my new RM valves when i install them

 

I believe all that is involved is putting the lapping compound on the valve seat and pulling the valve up against it and turnign it so that any kind of unevenness is ground down and you get a nice smooth tight seal. It is very necessary after a valve job.

 

Lapping the valves is a final step that some head people do to make sure you have full valve face and seat contact. If you can't get full contact with a light lapping then the valve must be and seats must be checked and corrected.

 

where would i get lapping compound at i wanna do this before i put the head on my car do everything right the first time

 

Talk to your machinist first because they probably vaccuum checked the valve to seat seal.

 

from T.O.O.:

I haven't lapped a valve, or seat since the late sixties. Lapping compound imbeds itself in the face of the valve and in the seats, causing premature erosion of both.I've wondered since day one why all the import head experts lap valves, but I've always attributed it to lack of experience. I'm not aware of any professional head shops that do domestic heads that lap valves either, but domestic head people have a lot more years of experience too.Lapping valves is a great way to insure that the valve job won't last any length of time. Honda doesn't recommend doing anything to seats (and valves) other than machining them too.I can also tell you that there are a LOT of stainless valves out there for imports that are junk because they're so soft. It doesn't take much use before they end up with the valve seat angle "pounded" into their faces, effectively ruining both the seal and flow capability.Valve problems can also be attributed to valve springs failing to control valve motion. I won't build any engine with Toda cams these days because there are no springs we've ever found that will last any length of time with them. When the springs go soft, valvetrain separation occurs and the valves typically end up being "dropped" on the seats, rather than eased to their seats by the closing ramps on the cams, thus pounding out the valves and seats.....The bottom line is that you NEVER lap a valve, or a seat. If the seat's machined concentrically, and the face of the valve has lass than .0005" runout, the engine will seal up.If you need to "see" where the seat is contacting the valve face, use some machinist's blue on the face of the valve and spin it against the seat with a lapping stick. The contact area will be "cleaned", showing the width of the seat.
--.....The Old One....

 

well ill be damned...

 

good info !! wish id know this before i built my motor.

 

I know of a special lapping compound that a top professional cylinder head shops uses

 

Dang, you beat me to it!

 

i'd be interested to know more about this, if it's not a trade secret. i'll also ask my machinist his opinion.

 

Actually, quite a few knowledgeable people such as Omniman, MAX_CFM, Portflow, West Coast Cylinder Heads, Baker Cylinder heads lap valves.

 

Glad you got yhat one Rocket, as I am obviously not a professional either along with the guys you mentioned. Buy the way v-8 dragracers use between 300-400 lbs. of seat pressure on the valves, Honda use between 50-75.

 

i'm guessing that the seat material, valve material, spring pressure (as DonF said), lapping compound and technique all factor in. i'd like to learn more.

 

im just using 220 and make sure that there are no dull spots on were the valve is in contact, valve job seems to be unconsistant.... some valves me and my friend only had to lap a little bit some of them he had to lap alot... im wondering if im ruining the seats =\

 

Should really be around 800-1000 grit. Do not attempt to compensate for actually needing a valve job, get the valves and seats cut. I think Rocket uses KY-Jelley.

 

i just got the valve job done

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">Should really be around 800-1000 grit. Do not attempt to compensate for actually needing a valve job, get the valves and seats cut. I think Rocket uses KY-Jelley.</TD></TR></TABLE>

LOL.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">Glad you got yhat one Rocket, as I am obviously not a professional either along with the guys you mentioned. Buy the way v-8 dragracers use between 300-400 lbs. of seat pressure on the valves, Honda use between 50-75. </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">Should really be around 800-1000 grit. Do not attempt to compensate for actually needing a valve job, get the valves and seats cut. I think Rocket uses KY-Jelley.</TD></TR></TABLE>

I think the last one is one of the funniest things I have read on a forum yet!!! Don your a funny guy, ----KY Jelly LOL !!!!!

I would want to keep that a secret too.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote"> I think Rocket uses KY-Jelley.</TD></TR></TABLE>

Must just use whats handy...

I lap valves with Red Mountain Dew.

 

Actually I use toothpaste (Colgate is preferred - more abrasive) The pro's use KY Jelly

 

wow i feel retarded..... nevermind!


Modified by importboi22 at 4:21 AM 3/7/2004

 

IM glad eveyone here has a sense of hunor

 

i feel stupid...

 

To be a little more helpful:

I use fine lapping compound that is available from PepBoys, Kragen's etc. I use it to check for valve to seat contact and where that contact is on the valve. This is iimportant to know. If a light lap does not show full contact then there is too much chatter, out-of-round etc so you'll need to correct things accordingly.

I am still waiting for some secret lapping compounding from a buddy of mine