As it sits now I have cylinder heads with valves in them, and nothing holding them up. I'm going to take it to a machine shop to have them assembled with my PAC springs and I was wondering what needs to be done to ensure that the valves are properly sealing on the seats. The guy on the phone mentioned something about the valves bouncing off the seat to ensure concentricity. Everything is brand new btw and also has a 5 angle comp. valve job. Thanks.

 

2 things you can do, get yourself some prussian blue dye (it doesn't dry up) and put a coating around the face of the valve, then spin the valve in its seat to make sure you have a nice uniform mating surface. OTHERWISE a good machine shop will put vaccuum on all the ports and see if there's any loss of vaccuum. If not, they're sealing, if there is, they're not. easy as that.

 

I have a bottle of prussian blue dye you can have if you want to pay for shipping. it's kind of hard to find otherwise

 

Pour some water in the ports. A small amount of seepage or none from the port to the combustion is okay.

 

That's a good tip. I'm surprised that allowing any seepage is acceptable.

 

I've used this method from way back in the day. Even saw them do it on one of the hotrod shows over the weekend. On a newly worked head I would probably target no leaking but even then it would be okay I think.

 

NOT ACCEPTABLE. Should be ZERo leakage. That's compression and vaccuum loss. Should be a perfect seal.

 

I always shoot for zero leakage but I'm always after every bit of performance. On a stocker it's a little different. I also do the leakage test with the spring installed at the correct installed height. Thus you know if it will leak vs holding the valve up with finger pressure.

If I have the heads off I always valve lap the seats and valve for maximum sealing.