Hey I was installing my valve springs this morning and when I hooked my air tube into the spark plug hole to pressurize the cyclinder to hold the valves up. 2 of my exhaust valves on cyclinders 2 and 5 they both let air just flow right by them...not much but enough to know that its not sealing right. Actaully #2 was the worst. Once I installed the bigger springs it help out a little but they still allowed air to blow by. These heads are not brand new. They are VORTEC's 906 castings off a 96 tahoe. Well I had a buddy take them to his shop and check them out and he said they were all good. So I intalled them on my block and now doin the valve springs the valves were not seat very well. Anything I can do while the heads are on the block still to try and get the to seat? I really do not want to remove the heads...Thanks and please help me out


Jason

 

Nothing while they are on the block.

You sure the compressed air isn't moving the piston down..moving the crank...movnig the cam...opening the valve some?

 

there is no way that the cam, or the crank would be able to affect it. I mean it was when I was just installin the springs. So everything was disconnected. With the cyclinder filled with compressed air, the valves are forced up and held there. So while the stock spring was in air was passin through the exhaust valve. I could physically feel it flowin throw as well as hear it. When I put the stiffer spring in it helped a little bit but didnt cure it. So I shot some carb spray into the exhaust port to see if that would help it. It did but barely, air still passes by it quickly. SO I might try sprayin it again to see if I can get it to seat. OH and BTW the motor is out of the car, its the one i'm building to go into the car.

 

Okay, FWIW, when you put in compressed air...yes, it forces "up" on the valves, but "down" on the piston...just keep that in mind.

My guess is the spray you're putting in is doing the sealing, not actually fixing anything.

If it were me, and I suspected that the valve wasn't sealing, I'd pull the head, and inpect the seat, if okay (and the valve face), I'd lap the valve in.

 

So your sayin that on a true comrpession stroke it might actually seat? But just cause theres not enough pressure there its not? I have the compressor at 100psi if that helps anything? I would also think that the spring would be enough to seat it like all the others. Sorry for being so dumb, just kinda confused. If it comes to it I will take the head back off and check it out.

Jason

 

nope.. it should be sealing NOW......


sorry to have to tell ya this, but you're going to have to pull that head off and fix the prob...



atleast you found out now and not later...

 

damnit there goes 50 bux down the drain....oh well like u said better late than never...