True lapping is not recommended because it will cause the valve to become unseated when it heats up. New Valves in not-new heads.
This test is easier to do on an overhead valve cylinder head removed from the engine, but it can be done on a valve-in-block flathead. The contact area between the two, especially on exhaust valves, is important for heat transfer and engine longevity. Grinding new valves is not recommended because the factory equipment is so much better than any machine shop grinders that the concentricity cannot be maintained.
I just had new valve seats professionally installed by a machine shop and I have a new set of valves ready to go in.
With the modern tooling, 3 and 5 angle cuts, in a word....no. The grooves made by lapping no longer match when the valve heats up. If you do decide to lap your valves, be sure to clean off ALL of the lapping compound when done.
Lapping of used, pitted valves and seats will likely not do anything except use up some time, effort, and lapping compound.
thanks.
Or is lapping just an old archaic process usually reserved for well-used / pitted valves and seats? Never woulda thought of it.) when the new valves get here what do i need to do to the head to make sure they seat properly? 1984 Bronco II custom roadster pkp w/351W1936 Plymouth P4,48K miles,1949 Dodge 1 ton rack body
The person who says it cannot be done should not interrupt the person who is doing it.
In other words you will make them worse. 1972 Mustang Mach I
Invert the block (easier to do this if it's mounted on an engine stand), and then pour a small amount of kerosene (or something similar - ATF might work) into each intake and exhaust port pocket against the valve head backside. Let the block sit overnight (and put a drain pan underneath it).
has anyone ever installed new valves?
The other option is a light lap (which I always use), it gives extra insurance against possible errors in machining. I just had new valve seats professionally installed by a machine shop and I have a new set of valves ready to go in. this is for an 85 110 head. any instructions would be great.
The person who says it cannot be done should not interrupt the person who is doing it.
As long as they’re not beat up and still seal, should be good to go. Or is lapping just an old archaic process usually reserved for well-used / pitted valves and seats? i think i can buy all the parts i need for about 1500 including a new head, piston/ rings, crank assembly, gaskets, cam chain/ tensioner, and seals. I have a replacement '75 CB500t head with valves that are in fairly good condition and valve seats that are for the most part not bad either with some light pitting at most. You'll need to have the valves and valve springs installed, but the cylinder head, tappets, and camshaft should not be installed. Is lapping necessary with new seats and valves? i've heard of lapping but i'm not sure how to do it. 80s......185 atc, Yamaha tri-moto 200, 85 200x with tons of work
After the lapping, I think I will try the "upside down leak test" suggested by Elwood (Smart idea.
There are measuring tools for checking the concentricity of the valve seat to the valve guide, and of the valve face to the valve stem. Yea, I'd lap them, but prior to doing that check for the stem to guide fit too. i removed the old valves and ordered new ones through honda. If you have an account, The forums of P15-D24.Com, Mopar cars and trucks from mid 1930s to late 1950s Valve Seat Lapping - Is it Necessary for New Valves and Seats?1951 B3B custom high side pkp
I have my block on a stand which will allow me to invert it. I, too, always lap new valves/seats after they've been replaced and cut or ground. 1949 Dodge 2.5ton rack body, 1943 John Deere LI, 1952 John Deere AOThe Brick (1950 PH Racetruck) 1948 B-1-BQ(yep, its a BBQ), 1949 COE, 1945 COE, many, many, B series 1/2 tons with parts The forums of P15-D24.Com, Mopar cars and trucks from mid 1930s to late 1950s
I'd add that a liquid leak test is always a good practice, too.
and on motosport.com they have a new oem head for 600 bucks. Or is lapping just an old archaic process usually reserved for well-used / pitted valves and seats? Is lapping necessary with new seats and valves? I guess i'm old school but I'd want to check them before everything got put back together and then find out you've got a leaker. Great advice from all you guys so a light lapping it will be. Good valve-to-seat contact is not just about sealing the combustion chamber and getting power out of the engine.
Is lapping necessary with new seats and valves? 80s......185 atc, Yamaha tri-moto 200, 85 200x with tons of work
Lapping might be enough to fix it, or the valve and/or valve seat may need to be trued up.
didnt see any on ebay.
Lapping compound is an abrasive, and not good for engine internal parts.
I have new valves also that I'd very much like to use rather than put them on the shelf. Seat width and placement can be checked with a sharpie marker, place 4 lines on the valve face, parallel to the stem equal distance apart, then "slap" the valve against the seat, the resultant wiping away of the marker will tell you what you need to know.
new heads are already cut and just need valves to be lapped Can’t lap coated valves What mechresto said.
By Cantedvalve, May 20, 2019 in 1969-70 Technical Forum. I just had new valve seats professionally installed by a machine shop and I have a new set of valves ready to go in. 83 YTM 200,84 200X,,85 350X basket case,86 350X parts trike,86 350Xroller needs top end, 86 250SX, If any of the kerosene leaks past any of the valves, then that leaking valve seal is not good enough. New valves in a used head sort of depends if the seats are still in good shape.