just wondering if that would send the valve seats too thin, resulting in the valve stems being too high and out of spec. anyone know? i wanted to get porting done on my head, but it's already been rebuilt once not very long ago.

 

Yes, you can grind down the valve seats and sink the valves too much. If the valves sit up too high, the retainers could potentially interfere with the rocker arms or cause problems with the rocker arm geometry.

The seats should be able to take several valve jobs, as long as they were not done (eg: messed up) by hand. All that will happen is that the valves will be sunk into the head a little more, and that'll give you a little more valve clearance. Somebody who works extensively with OHC cylinder heads should be able to measure the stem install height as well as cut the seat angles with a machine.

If it comes down to it, then the seats (or cylinder head) will need to be replaced. If it's just a non-VTEC head, then it would be easier to just buy a good used one that hasn't been decked or had the valve seats cut before. Buying another head would be much cheaper than have sixteen new valve seats put into the head and having the potential of them not putting them in straight or damaging the head with too much heat.

 

right. i don't think the shop that did it had a serdi machine. i think it was done by hand. but since it'll only have maybe 10k miles on it, if i remove the valves and put them back in w/o rebuilding, will it run? i tried it at 175k miles before the rebuild, and it wouldn't even run the compression was so bad. i guess the valves wear against the seats very uniquely. after the rebuild compression was great. but at <10k miles, could i do this?

 

I don't see why you would run into any problems taking out the valves and then reinstalling them after your port job. Obviously, label each valve though so that it goes back into it's original position and you should not have any problems.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IN VTEC &raquo;</TD></TR><TR><TD CLASS="quote">Yes, you can grind down the valve seats and sink the valves too much. If the valves sit up too high, the retainers could potentially interfere with the rocker arms or cause problems with the rocker arm geometry.

The seats should be able to take several valve jobs, as long as they were not done (eg: messed up) by hand. All that will happen is that the valves will be sunk into the head a little more, and that'll give you a little more valve clearance. Somebody who works extensively with OHC cylinder heads should be able to measure the stem install height as well as cut the seat angles with a machine.

If it comes down to it, then the seats (or cylinder head) will need to be replaced. If it's just a non-VTEC head, then it would be easier to just buy a good used one that hasn't been decked or had the valve seats cut before. Buying another head would be much cheaper than have sixteen new valve seats put into the head and having the potential of them not putting them in straight or damaging the head with too much heat.</TD></TR></TABLE>

ditto meng

 

Keeping the valves straight would be a good idea if you didn't want another valve job to recut the seats on the head and the valves.

Maybe you could lap the valves in with 1000grit lapping compound and see if all the seats are hitting all the way around and concentrically, and then have the ports leakdown tested using a vacuum gauge and a special sealing plate to see if the valves are sealing well enough. Shops that do heads quite frequently should have that port leakdown tester on hand.