Head rebuild advice

jeffball610 · Post by **jeffball610** » Thu Jan 25, 2007 8:59 pm

I bought a set of new Si SS valves and some 3G lifters and want to know if there are any precautions I should take when putting this together. I have valve stem seals and the valve guides seem to be fine. I"m just going to use the stock springs for now as my engine won't be built anytime soon. I'm just going for a stock non-ticking head at this point.

I'm cleaning the head including taking out the galley plugs and some light polishing of the exhaust runners. The new valves seem to have a rough pattern on head where it meets the cylinder head. (I'll get a pic) It's kinda like the edges a dime. I assume this is to help make a tight seal when they wear in, but I'm not sure. Do we actually lap these valves like the hot rod guys do? Let me know if anyone has any other advice.

Post by **DJpowerHaus** » Thu Jan 25, 2007 10:10 pm

You'll have to lap the valves. I've never done it but I'm sure some of the old times on this site could give you plenty of into on how to do that.

Bill Hincher · Post by **Bill Hincher** » Thu Jan 25, 2007 11:58 pm

I was up all night at a holiday inn ( express) so I was inspired to draw >;o)

HI JEFF!

4g63mightymax · Post by **4g63mightymax** » Fri Jan 26, 2007 8:26 am

Bill,
I really love all these drawings and diagrams.

Jeff,
Bill's diagram covered it very well. I did lap all the valves in 2 of my 4G63 engines with great success. Just go buy the $5 suction cup valve lapper tool and follow the diagram, your engine will thank you for it.
-Jeremy

Robert Venable · Post by **Robert Venable** » Sat Jan 27, 2007 1:41 am

Bill,

In your exp, which compounds do you use when lapping??

Do you start with and finish with a finer grit, or do you start with a rougher one and move to a finner grit as you get the seat smooth??

I've only lapped valves on mostly brand new bimmer parts (Except an old 8V92 I got to replace bent valves on). and I've only ever had to use the very fine lapping compound, never really had to mess with pitted seats.

BTW: Thanks for the old timmer's trick, never heard of it before. One thing that might be usefull is if you could show a picture of how you check valve stem to guide clearance. I'm sure a few guys might find this useful.

Bill Hincher · Post by **Bill Hincher** » Sat Jan 27, 2007 3:29 am

cutting the heavier valve compound with a little gas allowed you to create how fine the grade of compound you wanted, that was taught to me when I worked in a lawn mower shop, as a kid, ( before dirt) later I used that on the Honda 600 coupes because they ate valves for lunch.

Robert Venable · Post by **Robert Venable** » Sat Jan 27, 2007 7:11 pm

Bill,

When you say compititive valve grinds, are you referring to what many call 3 angle valve jobs? I believe this is the current term used, atleast from what I heard. I beleive that I was taught they are even offering up to (maybe even past) 5 angle valve jobs. My understanding is that they cut the seat of the valve to make the transition from the port to combustion chamber as smooth as possible for air flow reasons. Another thing they used to increase air flow is what I believe is called "back cut" valve stems that make the valve stems smaller near the head area to allow for more air flow.

Also, I thought with these multi angle valve jobs (which I was taught that almost ever Machineshop now does a 3 angle valve job when doing any valve job) that they cut the different angles into both the valve and seat. Do you know this to be incorrect???

Another thing you might be interested in, is a thing called Surface turbulence Valves. It is something done by My freinds at www.metricmechanic.com. From what they have told me, they have seem great gains with this. There is another process they do to the combustion chamber also, but I can't truely remeber how it works or if I am allowed to mention it to the public yet. Next time I talk to them I'll find out if it's ok to mention it and let you know about it after I get them to reexplain the benifits to me.

Bill Hincher · Post by **Bill Hincher** » Sat Jan 27, 2007 7:52 pm

there are all kinds of variations of compititive valve grinds 3 cuts, 5 cuts, custom cuts but in the end, it comes down to contact between the valve face and the valve seat, by making three cuts or five cuts you create a controlable contact area, its an interference angle in the seat that does not match the valve face . The depth of the interfence angle cut in the seat detirmines where the valve seats itself and the width of the interference cut detirmines heat transfer from the valve to the seat.

Factory grinds are more concerned with longevity, more surface of the valve facing is in contact with the valve seat to tranfer more heat to the cooling system in the head