valve lapping...and heads

[sthorvictor75du]

ok so i just finnished lapping the valves in the second set of heads for my 383, or so i think, im not one hundred percent sure what a finished valve seat and valve should look like, i tried to get rid of all the pitting in the exhaust valves and get them to look as smooth as possible, but could only do soo much.. as far as the intakes the same deal i tried to get them as smooth as possible but a couple have a fine groove or two, that i cant seem to lap out, is it a bigie?
is this easy to mess up?? and how much can it affect compresion (leaking ect)

thanks

 

[sthorvictor75du]

hope the photos turn out ok....

 

[swinger 367]

i can't say good or bad as far as your lap job but those valve stems don't look good, how do they measure? also after lapping be sure to clean the head well and then clean it again. the low miles 360 i bought last fall had worn bronze guides from someone not cleaning the lapping compound out of the heads.

 

[moper]

Lapping is the final step when the seats are re-finished. Old equipment needs them lapped in. The good equipment doesnt. You should not be trying to remove any pits. If there was a seat that was so bad it had carbon scaring all the way accross the margine (the exact spot the valve face meets the valve seat when it's closed) then it should have gotten the seat re-ground to fix it. So be careful. Lapping is not a repair operation but rather a final seating procedure whent the valve seats are marginal but ok.

 

[sthorvictor75du]

ok thanks i got the heads bolted on and the lap jobs turned out ok i tested a couple that i was iffy about by airing up the cylinders (using a cylinder leak gauge of some sort) and they arent leaking through the valves...theres a bit of a leak past the rings but thats another problem in the future, but i guess a guy wont know till its fired and run for a bit?

 

[sthorvictor75du]

ok thanks i got the heads bolted on and the lap jobs turned out ok i tested a couple that i was iffy about by airing up the cylinders (using a cylinder leak gauge of some sort) and they arent leaking through the valves...theres a bit of a leak past the rings but thats another problem in the future, but i guess a guy wont know till its fired and run for a bit?

 

[moper]

if the valves seal now, you're fine. It will only get better as it runs if the guides are good. I've run some really bad guides and seats without big short term issues in the past.

 

[sthorvictor75du]

the chemical that i used to clean the valves after the lapping leaves a whitish residue, and for the most part the valve guides were in decent shape with little wear (i had 48 valves to choose from), as far as the heads i rinsed them a few times and blew them out prior to install, as far as the heads valve guides wearing the heads i have on now will probably be throwaways in a year when i replace them with aluminum heads or refurbished 906's with hardened seats and new valves, im hoping they can take a bit of a beating in the next while,

 

[C130 Chief]

When lapping I shoot for an even gray band all the way around the valve head and seat, and no more. You won't be able to save a burned, bent or warped valve. Excessive lapping will also widen the sealing surface and sink the valves slightly. Don't expect miracles, lapping is no replacement for a valve job. But for cleaning up an otherwise OK head it's fine.