Changing valve seals using air chuck: If I have air leaks are the heads toast?

[piecesparts]

I agree, try tapping the valves with a hammer a couple of times to get them to seat, if they don't the heads will need to come off. It sounds like you may have driven a lot of city miles and carboned up the valves. However, even with the low miles, this would be an excellent time to tighten up the upper end of the motor and ensure the valves do not give you hell later. The motor is on the stand and you have some time(I hope) Go a step further and be satisfied that you did everything that you could do. BETTER Than having to take it apart after you have installed it in the next vehicle.

[WorkinLonghorn]

I agree with above. You probably don't want to hear this now that you've finished the seal job but I always hear (from machinists) that a motor with shot valve seals usually is in need of guide work anyway. If this was mine,I woulda taken the heads off and de-carboned etc.

[thecatseye66]

I finished up the seals about ten minutes ago. No problems at all once I learned to "seat" the valves by putting a block of wood against the valve spring assembly and give them a couple wacks before I took each one apart. I would just hook up the air after bringing each cylinder to TDC, then take off the rockers and give them a smack if there was air coming out of the exhaust or intake port. Once they seated I just tore them down and moved to the next.

I know a couple of you guys said I should do more teardown, but this motor is really clean. It is an original 45,000 mile 396 that came with a 2-barrel and was never driven hard. There is no sludge or carbon buildup anywhere--there were just a bunch of hardened and broken valve seals on the exhaust valves and it smoked a bit when I'd first start it up, but the compression is excellent. The motor had never even been out of the truck.

I'm putting in a new oil pump and I already put on a new timing chain and gears as well. I'm putting on an aluminum high-flow water pump and a quadrajet too. I picked up an original '68 q-jet high rise at a swap meet so it'll all look bone stock again when I'm done.

Thanks again for your input guys--